What is the difference between GH and KH in aquariums?

GH (General Hardness) measures dissolved calcium and magnesium minerals, which are essential for shrimp to molt successfully and for fish osmoregulation. KH (Carbonate Hardness) measures carbonates that buffer and stabilize pH. If KH drops to 0 in a standard tank, pH can crash to dangerous levels.

How does the drop-to-PPM conversion work for GH and KH tests?

For liquid drop test kits (like API), each drop used during the test equals 1 degree of hardness (dGH or dKH). Scientifically, 1 degree of hardness equals 17.86 ppm (parts per million). This calculator multiplies your drop count by 17.86 to give you the PPM value instantly.

What should I do if ammonia or nitrite are above 0 ppm?

Ammonia (NH3) and nitrite (NO2) above 0 ppm are highly toxic emergencies. Perform an immediate 30–50% water change, dose the tank with a detoxifier such as Seachem Prime, and stop feeding for several days until levels return to 0 ppm.

Why must KH be 0 for Crystal Red and Taiwan Bee shrimp?

Caridina shrimp like Crystal Reds and Taiwan Bees require highly acidic water (pH 5.8–6.8), achieved using active buffering soil. KH's job is to keep pH high and stable, so any KH will fight the soil, cause dangerous pH swings, and rapidly deplete the soil's buffering capacity.

How do I lower GH or KH in my aquarium?

You cannot safely remove dissolved minerals with chemicals. The only effective method is dilution: perform partial water changes using pure RO/DI (Reverse Osmosis Deionized) or distilled water, which have a GH and KH of 0.

What are the ideal water parameters for Cherry Shrimp (Neocaridina)?

Cherry Shrimp (Neocaridina davidi) thrive in GH 6–10 drops (107–179 ppm), KH 2–5 drops (36–89 ppm), pH 6.8–7.8, and nitrate below 20 ppm. Ammonia and nitrite must always be 0 ppm.

Why use liquid drop test kits instead of paper test strips?

Paper test strips are easily contaminated by moisture or skin oils, and color pads often bleed into each other making readings unreliable. Liquid titration tests use exact chemical reactions and provide lab-grade accuracy required for successfully breeding sensitive shrimp and fish.

Shrimply Tested | Free Aquarium Water Parameter Calculator for Shrimp & Fish

100% Free · No Login Required

Perfect aquarium water,
every single test.

Enter your test kit drop counts and instantly see if GH, KH, pH, ammonia, nitrite, and nitrate are in the safe zone for your shrimp or fish. No guesswork — just clear, colour-coded feedback tailored to your species.

Test My Water Now How It Works

🦐

5 Shrimp Profiles

Cherry, Crystal, Taiwan Bee & more

🐟

4 Fish Profiles

Discus to African Cichlids

📄

Free PDF Export

Download your test history log

How to Use This Calculator

Four simple steps to get instant, accurate feedback on your aquarium water — beginner-friendly!

Pick Your Species

Select your Target Species Profile and Tank Volume from the dropdowns.

Enter Test Results

Type your drop counts for GH & KH, and the ppm readings for pH, NH3, NO2, and NO3.

Read Your Feedback

Each card shows if you're in-range. The status bar gives your tank's overall safety score.

Save & Track

Click Save To Log Book, then Download Log PDF to track trends over time.

💡 New to liquid drop testing? See the step-by-step testing procedures section below for guidance before you start.

💧

General Hardness

Minerals for molting

🛡️

Carbonate Buffer

Stabilizes pH

⚗️

Acidity/Alkalinity

7.0 = neutral

☠️

NH3

Ammonia

Must be 0 ppm

⚠️

NO2

Nitrite

Must be 0 ppm

🌿

NO3

Nitrate

Keep it low

1. Target Species Profile

2. Tank Volume

How to test (KH/GH/NH3)

GH (General Hardness)

Target: --

0 DROPS = 0 PPM

↑ To Raise: Add liquid/powder remineralizer (e.g., SaltyShrimp GH+), crushed coral, or Wonder Shells.

↓ To Lower: Dilute minerals by performing water changes with pure RO/DI or Distilled water.

KH (Carbonate/Buffer)

Target: --

0 DROPS = 0 PPM

↑ To Raise: Add commercial alkaline buffers (KH+), crushed coral, or baking soda (dose carefully).

↓ To Lower: Use RO/DI water. Note: Active buffering soils naturally strip KH to 0.

pH (Acidity/Alkalinity)

Target: --

7.0 = Neutral

↑ To Raise: Increase surface agitation (air stone) to gas off CO2, or add crushed coral/limestone.

↓ To Lower: Add botanical tannins (Indian Almond Leaves, Alder Cones, Driftwood) or Peat moss.

Toxins (Ammonia & Nitrite)

Target: 0 PPM

NH3 (Ammonia)

NO2 (Nitrite)

⚠️ If Above Zero: Highly toxic. Perform an immediate 30-50% water change. Dose a detoxifier like Seachem Prime immediately.

NO3 (Nitrate)

Target: --

PPM

↓ To Lower: Nitrates are the end-product of the cycle. Remove them via routine 20% water changes. Add fast-growing floating plants (Frogbit, Salvinia, Hornwort).

Awaiting Data...

Enter test drops/ppm in the panels above.

KH (Carbonate Hardness) Procedure

Prevents wide pH swings in the aquarium.

Fill a clean test tube with 5 ml of water (to the line on the tube).
Add KH Test Solution 1 drop at a time, counting each drop.
Cap the tube and invert several times after each drop.
If you have difficulty discerning the color after the first drop: remove the cap, hold the tube over a white background, and look down through the tube.
STOP when the water turns from BLUE to BRIGHT YELLOW.

GH (General Hardness) Procedure

Measures Calcium & Magnesium levels.

Fill a clean test tube with 5 ml of water (to the line on the tube).
Add GH Test Solution 1 drop at a time, counting each drop.
Cap the tube and invert several times after each drop.
If you have difficulty discerning the color after the first drop: remove the cap, hold the tube over a white background, and look down through the tube.
STOP when the water turns from ORANGE to GREEN.

Ammonia (NH3) Test Kit Procedure

Critical for detecting toxic ammonia spikes.

Fill a clean test tube with 5 ml of aquarium water.
Add 8 drops of Ammonia Test Solution Bottle #1.
Add 8 drops of Bottle #2, then cap and shake tube for 5 seconds.
Wait 5 minutes for full color development before comparing to the chart.
Any reading above 0 ppm needs immediate action (water change + detoxifier).

Pro-Tip for Accuracy

If you have difficulty discerning the color after the first drop: remove the cap, hold the tube over a white background, and look down through the tube.

Reminder:

Each drop is equal to 1 degree of hardness (dGH/dKH).

Master Log Book

Date	Target	Tank Size	GH	KH	pH	NH3	NO2	NO3	Status

📊 Species Parameter Quick Reference

Compare ideal water conditions across different shrimp colonies and fish types.

Species / Target	GH (Drops / PPM)	KH (Drops / PPM)	Ideal pH	Max Nitrate (NO3)
🦐 Shrimp Colonies
Cherry / Neocaridina	6 - 10 Drops 107 - 179 PPM	2 - 5 Drops 36 - 89 PPM	6.8 - 7.8	< 20 ppm
Crystal Red (Caridina)	4 - 6 Drops 71 - 107 PPM	0 - 1 Drops 0 - 18 PPM	6.2 - 6.8	< 10 ppm
Taiwan Bee	4 - 5 Drops 71 - 89 PPM	0 Drops 0 PPM	5.8 - 6.4	< 10 ppm
Ghost Shrimp	5 - 8 Drops 89 - 143 PPM	5 - 8 Drops 89 - 143 PPM	7.0 - 8.0	< 20 ppm
Sulawesi Cardinal	6 - 8 Drops 107 - 143 PPM	4 - 8 Drops 71 - 143 PPM	7.8 - 8.5	< 10 ppm
🐟 API General Fish Guidelines
Soft Water (Discus, Neons)	0 - 3 Drops 0 - 54 PPM	0 - 3 Drops 0 - 54 PPM	6.0 - 7.0	< 40 ppm
Community (Tetras, Angelfish)	3 - 6 Drops 54 - 107 PPM	3 - 6 Drops 54 - 107 PPM	6.5 - 7.5	< 40 ppm
Hard Water (Guppies, Mollies)	6 - 11 Drops 107 - 196 PPM	6 - 11 Drops 107 - 196 PPM	7.0 - 8.0	< 40 ppm
Very Hard (African Cichlids)	11 - 22 Drops 196 - 393 PPM	11 - 22 Drops 196 - 393 PPM	7.8 - 8.5	< 40 ppm

* Note: While fish tolerate up to 40ppm Nitrate, breeding shrimp require much cleaner water. Always ensure Ammonia (NH3) and Nitrite (NO2) are strictly at 0 ppm for all species. Conversion calculated at 1 drop = 17.86 ppm.

📚 Complete Water Parameter Guide & FAQ

Everything you need to understand aquarium water chemistry — from absolute beginners to experienced breeders.

What is GH (General Hardness)?

GH stands for General Hardness and measures the total concentration of dissolved calcium (Ca²⁺) and magnesium (Mg²⁺) ions in your water. These are the two primary minerals that make water "hard." GH does not measure iron, sodium, or other minerals — only calcium and magnesium.

GH is measured in degrees of hardness (°dGH) or ppm (parts per million). With liquid drop test kits, each drop = 1°dGH = 17.86 ppm.

🦐 Why GH matters for shrimp

Molting: Calcium is the primary building block of a shrimp's new exoskeleton. Without enough GH, shrimp cannot harden their new shell after molting — this leads to "failed molts" where the shrimp gets stuck in its old shell and dies.
Ring of Death: A specific molting failure where the shrimp cannot shed the section around its mid-section, caused directly by insufficient calcium/magnesium.
Enzyme function: Magnesium is a cofactor in hundreds of biological processes. Low magnesium impairs immune function, reproduction, and general metabolism.
Breeding success: Female shrimp carrying eggs require extra calcium to produce egg casings and support the developing embryos.

🐟 Why GH matters for fish

Osmoregulation: Fish constantly regulate the flow of water and salts across their skin and gills. Hardness minerals help maintain the correct salt balance inside the fish's body.
Gill function: Calcium strengthens gill tissue and helps fish extract oxygen efficiently. Very soft water can cause gill erosion over time.
Spawning: Many species require specific GH to trigger spawning behaviour. Cichlids need hard water; discus and tetras need soft water.
Egg viability: Fish eggs need appropriate mineral levels to develop properly. Incorrect GH causes poor hatch rates.

📊 GH Reference Ranges

Classification	Drops (°dGH)	PPM	Suitable For
Very Soft	0–3	0–54	Discus, Cardinals, Neon Tetras
Soft	4–6	71–107	Crystal Red / Taiwan Bee Shrimp
Medium Hard	6–10	107–179	Cherry Shrimp, Community Fish
Hard	10–15	179–268	Guppies, Mollies, Livebearers
Very Hard	15+	268+	African Cichlids, Rift Lake species

⬆️ How to raise GH

✅ Liquid/powder remineralizer (SaltyShrimp GH+, Bee Shrimp Mineral) — most precise, fast-acting, dose per instructions
✅ Wonder Shells — dissolve slowly, good for ongoing maintenance
✅ Crushed coral or cuttlebone in a mesh bag in the filter
✅ Limestone rocks — passive, very slow raise
✅ Use tap/well water if your source has high GH naturally
⚠️ Always add slowly and retest — sudden spikes stress shrimp

⬇️ How to lower GH

✅ Water changes with RO/DI or distilled water (GH = 0) — only reliable method
✅ Switch top-off water to RO/DI — evaporation leaves minerals behind, concentrating GH over time
✅ Remove mineral sources — check for coral, limestone, shells, or Wonder Shells
❌ Do NOT use water softener resin pillows — they swap Ca/Mg for sodium ions, which is harmful or lethal to shrimp and many fish
❌ Do NOT use "water softener" tap water — same reason, sodium-based

Why does GH rise even without adding anything?

Evaporation is the culprit. When water evaporates from your tank, the minerals stay behind — only the pure water molecules escape. Over time this concentrates the GH. Always top off evaporation losses with pure RO/DI or distilled water (not treated tap water), and only use your normal water mix for actual water changes.

What is the difference between GH and TDS?

TDS (Total Dissolved Solids) measures everything dissolved in the water — including GH minerals, KH carbonates, nitrates, medications, tannins, and more. GH only measures calcium and magnesium. A tank can have a high TDS but low GH (e.g. lots of tannins or medications) or low TDS with correct GH (perfectly remineralised RO water). For shrimp, monitoring both GH specifically and overall TDS is recommended.

What is KH (Carbonate Hardness)?

KH stands for Carbonate Hardness (also called Alkalinity or dKH). It measures the concentration of carbonate (CO₃²⁻) and bicarbonate (HCO₃⁻) ions in your water. These ions act as a chemical buffer — they absorb excess acids before they can change the pH.

Think of KH as a pH shock absorber. The higher your KH, the more resistant your water is to sudden pH swings. A tank with KH = 0 has no buffer at all and pH can crash overnight.

🔬 How KH buffers pH (the chemistry)

CO₂ from fish respiration and bacterial decomposition dissolves in water to form carbonic acid (H₂CO₃). Without KH, this acid accumulates and crashes pH.

With adequate KH, the bicarbonate ions neutralize this acid:
HCO₃⁻ + H⁺ → H₂O + CO₂

This reaction consumes the dangerous hydrogen ions before they can acidify the water, keeping pH stable.

⚠️ Signs of KH problems

pH crash (low KH): pH drops 1–2 units overnight. Fish at the surface gasping. Shrimp acting erratic or dying without visible cause.
Wild pH swings: pH is very different morning vs evening — plants consume CO₂ during the day, raising pH; respiration at night lowers it. Low KH makes this swing extreme.
Caridina tanks: Constant unexplained parameter fluctuations despite using buffering soil can indicate KH is interfering.
High KH signs: Difficulty getting pH below 7.4. Buffering soil being depleted rapidly. Mineral deposits (white crust) around tank rim.

🦐 Why Caridina shrimp MUST have KH = 0

Crystal Red, Crystal Black, Taiwan Bee, and other Caridina species evolved in soft, acidic mountain streams. They require pH in the 5.8–6.8 range, which breeders achieve using active buffering soil (ADA Aquasoil, Fluval Stratum, etc.). This substrate contains acidic compounds that continuously lower and stabilize pH.

Here's the conflict: KH's entire job is to resist pH changes and keep pH higher. Every carbonate ion in the water attacks and neutralizes the soil's acidic compounds. This depletes the soil within months instead of years (active soil typically costs $30–$80+ for a tank's worth).

Additionally, the battle between KH and the soil causes erratic pH swings — sometimes within hours — which is far more dangerous to sensitive Caridina than a stable wrong pH. Always use RO/DI water (KH = 0) as your water source for Caridina tanks.

⬆️ How to raise KH

✅ Seachem Alkalinity Buffer / API pH Stabilizer — precise, dissolve outside tank first
✅ Baking soda (sodium bicarbonate) — budget option, ½ tsp per 20 gal raises ~4 dKH. Dissolve fully before adding.
✅ Crushed coral in filter bag — slow, gentle, continuous buffering. Takes 24–72 hrs to show effect.
✅ Aragonite substrate — continuously buffers from below. Good for Rift Lake cichlid tanks.
✅ Seashells or cuttlebone — very slow, passive raise
⚠️ Raise gradually — fast KH increase causes pH spike that can shock tank inhabitants

⬇️ How to lower KH

✅ Water changes with RO/DI or distilled water (KH = 0) — most reliable method
✅ Peat moss in filter — tannins and humic acids neutralize carbonates over days/weeks
✅ Indian Almond Leaves / Alder Cones — slower but natural tannin source
✅ Driftwood — releases tannins gradually
❌ Never use strong acids (muriatic acid, etc.) — creates extremely dangerous localized pH crashes and toxic chlorine gas
❌ Do not add CO₂ to lower KH — CO₂ lowers pH temporarily but not KH itself

Is KH the same as alkalinity?

In freshwater aquarium chemistry, KH and alkalinity are used interchangeably and your test kit measures essentially the same thing. In scientific contexts they can differ slightly, but for practical fishkeeping purposes, the KH test result = your water's alkalinity / buffering capacity. Both are expressed in the same dKH or ppm units.

My KH keeps dropping — what is consuming it?

KH is consumed by: (1) the natural buffering process — absorbing CO₂ and acids from respiration and decomposition; (2) active buffering soil — this is intentional for Caridina tanks; (3) dense plant growth — plants can consume carbonates as a carbon source; (4) biological nitrification — the bacteria converting ammonia produce nitric acid, which consumes KH. In established tanks, KH should remain relatively stable. If it's dropping rapidly in a non-Caridina tank, increase your water change frequency with KH-containing water.

What is pH?

pH measures the acidity or alkalinity of your water on a logarithmic scale from 0–14. 7.0 is neutral. Below 7 is acidic; above 7 is alkaline (basic). Because the scale is logarithmic, a pH of 6 is ten times more acidic than pH 7, and pH 5 is one hundred times more acidic than pH 7.

pH is one of the most important parameters because it affects the toxicity of other parameters (especially ammonia), the activity of beneficial bacteria, enzyme function, and whether fish and shrimp can survive at all.

🦐 pH for shrimp

Neocaridina (Cherry): pH 6.8–7.8 — adaptable and forgiving
Caridina (Crystal/Bee): pH 6.2–6.8 — needs active soil to maintain
Taiwan Bee: pH 5.8–6.4 — most sensitive, strictest requirements
Sulawesi Cardinal: pH 7.8–8.5 — the opposite extreme, needs alkaline
Wrong pH = failed molts, poor breeding, shortened lifespan

🐟 pH for fish

Discus, Cardinals: pH 5.5–6.5 — blackwater species
Most community fish: pH 6.5–7.5 — wide tolerance
Guppies, Mollies: pH 7.0–8.0 — prefer harder water
African Cichlids: pH 7.8–8.5 — alkaline Rift Lake conditions
Rapid pH changes more dangerous than wrong pH — always adjust slowly

⚗️ pH & ammonia toxicity

This is critical: the same ammonia reading is far more deadly at high pH.

Ammonia exists in two forms — toxic free ammonia (NH₃) and relatively harmless ammonium (NH₄⁺). At higher pH, the balance shifts dramatically toward the deadly NH₃ form.

At pH 7: ~0.5% is toxic NH₃
At pH 8: ~5% is toxic NH₃ (10× worse)
At pH 9: ~50% is toxic NH₃ (100× worse)

⬆️ How to raise pH (if too acidic)

✅ Increase surface agitation — air stones or surface-skimming powerheads gas off dissolved CO₂, which is the #1 cause of low pH. Often raises pH by 0.3–0.7 units.
✅ Raise KH — a tank with more buffer will naturally sit at a higher stable pH
✅ Crushed coral / limestone in filter — raises both KH and pH steadily
✅ Reduce organic load — less waste = less CO₂ = higher pH
✅ Remove peat moss, driftwood, or botanicals if using them in a tank that needs higher pH
⚠️ Commercial pH-Up products work but cause rapid swings — use cautiously

⬇️ How to lower pH (if too alkaline)

✅ Indian Almond Leaves (Catappa) — release humic acids and tannins naturally. 1–2 large leaves per 10 gal, replace when pale/disintegrated.
✅ Driftwood (Spider Wood, Mopani, Cholla) — tannin-releasing, soak 1 week first to reduce colour
✅ Peat moss in a filter sock — highly effective, remove when pH target reached
✅ Active buffering soil — ADA Aquasoil, Fluval Stratum; ideal for Caridina tanks
✅ Reduce KH first — high KH is the most common reason pH won't come down
❌ Avoid pH-Down acid products in shrimp tanks — can cause localized lethal acidic pockets

Why is my pH different in the morning vs evening?

This is called the diel pH swing and is completely normal in planted tanks. During the day, plants and algae absorb CO₂ for photosynthesis, reducing the amount of carbonic acid in the water — this raises pH. At night, all organisms respire and produce CO₂, which lowers pH again. A swing of 0.3–0.5 pH units is normal. Larger swings (0.5+) suggest low KH. Always test pH at the same time of day for consistent comparisons — morning (before lights on) gives the lowest reading, evening the highest.

Is it better to have a stable wrong pH or an unstable correct pH?

Almost always: stable wrong pH is better than unstable "correct" pH. Fish and shrimp can acclimate to pH values outside their ideal range if the change is gradual and stable. What kills them is rapid swings. A pH crash of 0.5 or more units within a few hours can kill an entire tank. Always prioritize stability over chasing the "perfect" number, and make any adjustments gradually over days, not hours.

What is Ammonia (NH3 / NH4⁺)?

Ammonia is a nitrogenous waste product produced continuously in every aquarium. It comes from fish and shrimp excretion (primarily through the gills), uneaten food decomposing, dead plant matter, dead animals, and the breakdown of any organic material. It is the first and most acutely toxic compound in the nitrogen cycle.

Ammonia exists in two chemically linked forms: free ammonia (NH₃) — highly toxic, and ammonium (NH₄⁺) — relatively harmless. Your test kit measures total ammonia nitrogen (both combined). The ratio of toxic NH₃ increases with higher pH and higher temperature.

💀 What ammonia does to fish & shrimp

Gill damage: Ammonia burns and destroys gill tissue, preventing oxygen uptake. Fish gasp at the surface even in oxygenated water.
Neurological damage: Even sub-lethal ammonia causes brain and nervous system damage, resulting in erratic swimming, loss of balance, and seizures.
Immune suppression: Chronic low-level ammonia (0.25–0.5 ppm) weakens the immune system, making fish/shrimp susceptible to bacterial and fungal infections.
Organ failure: Kidneys and liver are damaged by prolonged ammonia exposure, causing internal bleeding and eventual death.
Shrimp sensitivity: Shrimp are 5–10× more sensitive to ammonia than most fish. Even 0.1 ppm can cause stress and molting failure.

📋 Ammonia toxicity levels

0 ppmSafe. Target for all tanks at all times.

0.25 ppmStress begins. Gill damage in prolonged exposure. Shrimp already at risk.

0.5 ppmSignificant damage. Immune suppression. Many shrimp die within 24 hrs.

1.0 ppmLethal for most shrimp and sensitive fish within hours.

2+ ppmRapidly lethal. Emergency water changes + Prime immediately.

🚨 Emergency response if ammonia > 0

Stop feeding immediately — all food adds more ammonia
Perform a 30–50% water change with dechlorinated water at the same temperature
Dose Seachem Prime at full tank volume — detoxifies ammonia for 48 hrs while beneficial bacteria process it
Add extra aeration — air stones help ammonia off-gas and support bacteria
Re-dose Prime every 48 hours and retest daily until readings hit 0
Do NOT clean the filter — your beneficial bacteria colony lives there
Remove any dead fish/shrimp immediately — they add more ammonia rapidly

What are the most common causes of ammonia spikes?

🔴 New tank / uncycled aquarium — no beneficial bacteria yet to process ammonia
🔴 Dead fish or shrimp not found/removed promptly
🔴 Overfeeding — uneaten food rots and releases ammonia
🔴 Filter failure — power outage, broken pump, or clogged impeller kills bacteria
🔴 Antibiotics or medications — many kill the beneficial bacteria in your filter
🔴 Filter media replaced all at once — throws away the entire bacterial colony
🔴 Filter media cleaned in tap water — chlorine kills beneficial bacteria
🔴 Overstocking — too many animals producing more waste than bacteria can process

Does Seachem Prime actually make ammonia safe?

Prime works by binding ammonia into a non-toxic complex that your beneficial bacteria can still process normally. It doesn't remove ammonia — it temporarily converts it from the toxic NH₃ form into a bound form that won't harm fish or shrimp for approximately 24–48 hours. During that window, your bacteria continue breaking it down into nitrite and then nitrate. This is why you must re-dose every 48 hours if ammonia is persistently high, and why you should still do water changes — Prime is a detoxifier, not a cure. Your test kit will still show ammonia present after dosing Prime, which is expected and correct.

What is Nitrite (NO₂)?

Nitrite is the second toxic compound in the nitrogen cycle. It is produced when beneficial bacteria of the genus Nitrosomonas convert ammonia into nitrite. A second group of bacteria (Nitrospira) then converts nitrite into the far less toxic nitrate.

Nitrite is almost as acutely toxic as ammonia but works through a completely different mechanism — it attacks the blood itself rather than the gills directly. Any reading above 0 ppm is an emergency.

🩸 What nitrite does to fish & shrimp

Methemoglobinemia ("Brown Blood Disease"): Nitrite ions pass through the gills into the bloodstream and bind to haemoglobin (the protein that carries oxygen). This converts red haemoglobin to brown methemoglobin, which cannot carry oxygen. Fish literally suffocate from the inside out, even in fully oxygenated water.
Shrimp haemolymph damage: Shrimp have haemolymph (blue blood) instead of haemoglobin, but nitrite disrupts their oxygen-carrying capacity similarly.
Stress and immune collapse: Even low nitrite levels chronically suppress immunity. Bacterial infections, fungal outbreaks, and mysterious deaths often trace back to persistent low-level nitrite.
Visual symptoms: Fish may appear lethargic, cluster near the surface or near oxygenation, have rapid gill movement, and may show a brownish tinge to their gills.

📋 Nitrite toxicity levels

0 ppmSafe. The only acceptable reading in an established tank.

0.1 ppmImmune suppression begins. Shrimp highly stressed.

0.5 ppmBlood oxygen capacity significantly reduced. Deaths possible.

1+ ppmRapidly lethal. Immediate large water change required.

Note: Salt (sodium chloride) helps fish resist nitrite toxicity as chloride ions compete with nitrite for uptake. Not appropriate for shrimp tanks.

Why does nitrite spike in mid-cycle ("the nitrite spike")?

During the nitrogen cycle, Nitrosomonas bacteria (ammonia → nitrite) establish themselves first and faster. This means ammonia gets converted to nitrite faster than Nitrospira bacteria (nitrite → nitrate) can process it — creating a temporary nitrite buildup. This "mini-cycle" is normal and expected in new tanks. It typically peaks 1–2 weeks after ammonia begins dropping and resolves within 2–6 weeks as the Nitrospira colony grows. During this period, daily partial water changes + Prime dosing is the standard management approach.

My tank was cycled — why did nitrite suddenly appear?

A previously stable tank showing nitrite usually means a "mini-cycle" — partial bacterial colony crash. Common causes: filter media cleaned in tap water (chlorine kills bacteria), filter power outage for several hours, heavy medication (especially antibiotics), sudden large increase in stocking or feeding, or removing/replacing a large portion of the substrate. The fix is the same as cycling: water changes + Prime + patience. Also consider adding bottled bacteria (Seachem Stability, Dr. Tim's) to speed up re-establishment.

What is Nitrate (NO₃)?

Nitrate is the final product of the nitrogen cycle. It's produced when beneficial bacteria convert nitrite into nitrate. Unlike ammonia and nitrite, nitrate is relatively harmless at low levels — but it accumulates continuously and becomes problematic at high concentrations, especially for sensitive species.

Nitrate is the parameter that water changes primarily manage. Since there's no standard beneficial bacteria that removes it in typical aquariums, regular water changes and live plants are the primary control methods.

📊 Effects of high nitrate

Chronic stress: Long-term exposure suppresses the immune system and reduces lifespan even at levels that don't cause acute symptoms
Reproductive failure: Shrimp stop breeding, fish produce fewer/non-viable eggs at elevated nitrate
Algae blooms: Nitrate is plant food — high levels fuel explosive algae growth
Shrimp sensitivity: Shrimp are far more sensitive than fish. Target <10 ppm for breeding Caridina, <20 ppm for Neocaridina
Reduced color: Fish and shrimp often show less vibrant coloration under chronic nitrate stress
Wilting plants: Counterintuitively, very high nitrate can indicate poor plant health and nutrient imbalance

📋 Nitrate tolerance levels

0–10 ppm — Ideal for Caridina & breeding shrimp tanks

10–20 ppm — Good for Neocaridina and sensitive fish

20–40 ppm — Acceptable for most community fish; stressful for shrimp

40–80 ppm — Harmful long-term; water change needed immediately

80+ ppm — Acutely dangerous; large emergency water change required

⬇️ How to lower & control nitrate

✅ Water changes — 20–30% weekly is the gold standard. The only reliable mechanical removal method.
✅ Floating plants (Frogbit, Salvinia, Duckweed) — consume nitrate aggressively via photosynthesis, can reduce 10–20 ppm/week
✅ Dense stem plants (Hornwort, Guppy Grass, Water Sprite) — excellent nitrate consumers
✅ Reduce feeding — every bit of uneaten food eventually becomes nitrate
✅ Vacuum substrate regularly — detritus in gravel is a major nitrate source
✅ Anaerobic filter media (deep sand beds, ceramic nitrate reducers) — bacteria in low-oxygen zones can convert nitrate to nitrogen gas
✅ Nitrate-removing resins (API NITRA-ZORB) — emergency use, needs regular replacement

🌱 Best plants for nitrate control

🥇 Frogbit — floating, fast-growing, zero substrate needed, shrimp love grazing on roots
🥇 Salvinia (S. natans or S. minima) — aggressive nitrate consumer, creates shaded areas shrimp love
🥈 Hornwort — free-floating or planted, extremely fast growth = high nitrate uptake
🥈 Guppy Grass (Najas guadalupensis) — undemanding, fast growing, great for shrimp tanks
🥉 Java Moss — slower than the above but provides biofilm surfaces shrimp graze on constantly
🥉 Duckweed — fastest grower, needs management or will cover the surface completely

Why is my nitrate always high even with regular water changes?

Several possibilities: (1) Your tap water itself contains nitrate — test your tap water. Some municipal supplies run 10–20 ppm; if so, you're adding nitrate with every water change. Solution: use RO/DI water. (2) Overfeeding — the single biggest controllable source. (3) Overstocking — too many animals for your biological capacity. (4) Detritus accumulation — rotting matter in the substrate is a constant source. Vacuum gravel during water changes. (5) Dead material — decaying plant leaves left in the tank.

🔄 What is the Nitrogen Cycle?

The nitrogen cycle is the biological process that makes aquariums liveable. Without it, ammonia from fish waste would build up and kill everything within days. It is performed entirely by colonies of beneficial bacteria that live in your filter media, substrate, and decorations.

Step 1

Fish Waste / Uneaten Food

→ releases Ammonia (NH₃)

→

Step 2 — Nitrosomonas bacteria

Ammonia (NH₃)

→ converted to Nitrite (NO₂)

→

Step 3 — Nitrospira bacteria

Nitrite (NO₂)

→ converted to Nitrate (NO₃)

→

Step 4

Nitrate (NO₃)

Removed by water changes & plants

How long does cycling a new tank take?

A fishless cycle typically takes 4–8 weeks. Week 1–2: ammonia rises. Week 2–3: nitrite appears as Nitrosomonas bacteria establish. Week 3–5: nitrite peaks and begins falling as Nitrospira grows. Week 4–8: both ammonia and nitrite consistently read 0, nitrate appears. The tank is cycled when you can add a dose of ammonia and both ammonia and nitrite reach 0 within 24 hours. Bottled bacteria products (Seachem Stability, Dr. Tim's One and Only) can speed this to 1–2 weeks if dosed correctly.

What is "New Tank Syndrome"?

New Tank Syndrome describes fish/shrimp dying in a new aquarium that hasn't completed the nitrogen cycle. Without established beneficial bacteria, ammonia builds to lethal levels within days. Animals appear healthy, then suddenly become lethargic and die. The solution is to either cycle the tank without livestock (fishless cycling) or perform daily water changes and dose Prime throughout the cycling period if livestock is already present. Never add expensive or sensitive species to an uncycled tank.

How do I speed up cycling a new tank?

🚀 Seed with established filter media — a handful of gravel, a sponge, or filter floss from an established healthy tank instantly transfers millions of bacteria
🚀 Bottled bacteria (Seachem Stability, Dr. Tim's One and Only, Fritz Turbo Start) — add daily for first 2 weeks
🚀 Keep temperature at 78–82°F (26–28°C) — bacteria grow faster in warmer water
🚀 Ensure high oxygenation — beneficial bacteria need lots of oxygen
🚀 Don't do large water changes during cycling — this dilutes the ammonia the bacteria need to grow
🚀 Don't add ammonia-blocking products (except Prime in emergencies) — bacteria need accessible ammonia to grow

Can the cycle "crash" in an established tank?

Yes — this is called a "mini-cycle." Causes include: (1) filter power outage for 4+ hours (bacteria die without oxygen), (2) cleaning filter media in tap water (chlorine kills bacteria), (3) replacing all filter media at once, (4) using antibiotics or treatments that kill bacteria, (5) dramatic temperature changes. Signs: ammonia or nitrite suddenly appear in a previously stable tank. Treatment: water changes + Prime + bottled bacteria + stop feeding.

🧪 Liquid Drops vs Paper Test Strips

✅ Liquid drop tests (Recommended)

Use precise chemical reactions with exact reagent volumes
Lab-grade accuracy — same as professional water testing labs use
Results read by counting drops (GH/KH) or comparing colour to chart (pH, NH3, NO2, NO3)
Not affected by humidity, skin oils, or storage conditions as severely
Cost per test is very low (a single kit tests hundreds of times)
API Master Test Kit is the industry standard for hobbyists

❌ Paper test strips (Not recommended)

Colour pads bleed into each other, making readings ambiguous
Degraded by humidity — even opening the tube exposes all remaining strips
Oils from fingers contaminate the pads
Accuracy is ±25–50% in best conditions — far too imprecise for sensitive species
Cannot distinguish between "safe ammonia" and "dangerous ammonia" levels
Acceptable only for quick checks in hardy community fish tanks

How often should I test my aquarium water?

🆕 New/cycling tank: Test ammonia and nitrite daily until both read 0 for 1 week straight
🦐 Active shrimp breeding setup: Full test (all 6 parameters) weekly, especially after water changes
🐟 Established community tank: Full test monthly; ammonia/nitrite test after any deaths, new additions, or medication use
🚨 After any changes: Always retest 24–48 hours after adding new products, adjusting parameters, or introducing new livestock
💡 Always log results in the Log Book above — trends over time are often more informative than single readings

Tips for getting accurate test results every time

✅ Rinse test tubes with the water you're testing before filling — residue from previous tests skews results
✅ Test at the same time each day for consistency (pH varies throughout the day)
✅ Wait the full reaction time before comparing colours (especially NH3 — 5 full minutes)
✅ Read colour in natural daylight or against a white background under a bright light — artificial yellow lighting distorts colours
✅ Look down through the test tube from above against a white background for GH/KH end-point detection — much easier to see the colour change
✅ Shake well when instructed — NH3 Bottle 2 especially needs vigorous shaking
✅ Store reagents upright at room temperature, away from direct sunlight and heat
✅ Check expiry dates — expired reagents give false low readings, especially for ammonia

How does the Drop-to-PPM conversion work?

For GH and KH liquid tests, you count how many drops it takes to change the water's colour. Each drop = 1 degree of hardness (°dGH or °dKH). Scientifically, 1°dGH = 17.86 ppm (CaCO₃ equivalent). This calculator automatically multiplies your drop count by 17.86 to show the PPM equivalent. This conversion applies to all standard liquid drop hardness test kits (API, Salifert, Sera, JBL etc.) using the standard 5ml test tube fill.

What is RO/DI water and do I really need it?

RO/DI stands for Reverse Osmosis / Deionized water. It is water that has been pushed through a membrane (RO) that removes ~95–99% of dissolved minerals and then through a resin bed (DI) that removes the remaining ions. The result is essentially pure water with GH = 0, KH = 0, and TDS ≈ 0.

Do you need it? For Neocaridina (Cherry Shrimp) and most community fish with tap water in a reasonable GH range (4–12 drops) — probably not. For Caridina (Crystal Red, Taiwan Bee), Discus, or any species requiring soft acidic water — yes, absolutely. You cannot reliably achieve target parameters using typical tap water for these species.

RO units for home use cost $50–$150 and pay for themselves quickly vs buying distilled water. Alternatively, many fish stores sell RO water for $0.25–$0.75/gallon.

Why do my parameters change after water changes?

This is normal and expected — you're diluting the tank water with your replacement water, so the resulting parameters are a blend of the two. To minimise disruption: (1) always prepare replacement water to match your target parameters before adding it (pre-mix RO water with remineralizer if needed), (2) match the temperature exactly, (3) add water slowly rather than dumping it in, (4) never change more than 30% at once in a shrimp tank, (5) always dechlorinate tap water before adding. After a water change, wait 1–2 hours before testing to let the water mix fully.

Perfect aquarium water,every single test.

How to Use This Calculator

GH (General Hardness)

KH (Carbonate/Buffer)

pH (Acidity/Alkalinity)

Toxins (Ammonia & Nitrite)

NO3 (Nitrate)

Awaiting Data...

KH (Carbonate Hardness) Procedure

GH (General Hardness) Procedure

Ammonia (NH3) Test Kit Procedure

Pro-Tip for Accuracy

Master Log Book

📊 Species Parameter Quick Reference

📚 Complete Water Parameter Guide & FAQ

What is GH (General Hardness)?

🦐 Why GH matters for shrimp

🐟 Why GH matters for fish

📊 GH Reference Ranges

⬆️ How to raise GH

⬇️ How to lower GH

What is KH (Carbonate Hardness)?

🔬 How KH buffers pH (the chemistry)

⚠️ Signs of KH problems

🦐 Why Caridina shrimp MUST have KH = 0

⬆️ How to raise KH

⬇️ How to lower KH

What is pH?

🦐 pH for shrimp

🐟 pH for fish

⚗️ pH & ammonia toxicity

⬆️ How to raise pH (if too acidic)

⬇️ How to lower pH (if too alkaline)

What is Ammonia (NH3 / NH4⁺)?

💀 What ammonia does to fish & shrimp

📋 Ammonia toxicity levels

🚨 Emergency response if ammonia > 0

What is Nitrite (NO₂)?

🩸 What nitrite does to fish & shrimp

📋 Nitrite toxicity levels

What is Nitrate (NO₃)?

📊 Effects of high nitrate

📋 Nitrate tolerance levels

⬇️ How to lower & control nitrate

🌱 Best plants for nitrate control

🔄 What is the Nitrogen Cycle?

🧪 Liquid Drops vs Paper Test Strips

✅ Liquid drop tests (Recommended)

❌ Paper test strips (Not recommended)

Perfect aquarium water,
every single test.