Shrimp Tank Water Parameters: pH, GH, KH and TDS
Water parameters are the most talked-about topic in shrimp keeping. pH, GH, KH, TDS: the abbreviations look confusing at first, but they come down to a few simple ideas. This guide covers what each value does, the commonly accepted ranges for Neocaridina and Caridina, how to test and the most common mistakes. The goal is not perfect numbers; it is stable, predictable water your shrimp are comfortable in.
The most important rule: stability
Whatever values you aim for, what matters most to shrimp is stability. Water that sits slightly outside the ideal range but has stayed the same for months is usually better than ideal numbers that keep shifting. Sudden changes in pH, temperature or minerals quickly affect molting and appetite. If you need to correct something, do it in small steps over several days rather than with one large water change.
Also, read each test result together with the others. Products that raise KH also push pH up, for example. Testing pH, GH, KH and TDS on the same day gives you the whole picture.
Water parameters table
| Parameter | Neocaridina | Caridina (Crystal / Bee) |
|---|---|---|
| Temperature | 20–25 °C (68–77 °F) | 20–23 °C (68–73 °F) |
| pH | 6.5–8.0 | 5.8–6.8 |
| GH | 6–10 °dH | 4–6 °dH |
| KH | 2–6 °dH | 0–1 °dH |
| TDS | 150–250 ppm | 100–160 ppm |
| Ammonia / nitrite | 0 | 0 |
| Nitrate | Below 20 mg/L | Below 20 mg/L |
These are general values widely accepted in the hobby; sources differ slightly. What matters is staying within the range you choose and avoiding sudden jumps. Starting close to the water your shrimp were bred in makes acclimation easier.
pH
pH shows how acidic or alkaline the water is: 7 is neutral, below 7 is acidic, above 7 is alkaline. The scale is logarithmic, so pH 6 is ten times more acidic than pH 7. Even a 0.5 difference is a real change in water chemistry. In a shrimp tank, do not chase pH on its own; think of it together with KH and your substrate, which largely set it.
Neocaridina tolerate a wide pH range. In Caridina tanks, pH is usually held in the 5.8–6.8 band with a buffering active substrate. Be very careful with pH-lowering chemicals: they can move pH quickly and stress shrimp. Slow methods are safer than sudden fixes.
GH (general hardness)
GH measures dissolved calcium and magnesium. Shrimp need these minerals to build their shells and molt properly. When GH is too low, molting problems appear; when it is too high, shedding the old shell can become difficult. GH is usually given in German degrees (°dH).
To raise GH, use a shrimp mineral containing calcium and magnesium. Add it to your water-change water, not straight into the tank; uncontrolled dosing causes sudden hardness spikes. To lower GH, mix in RO water gradually.
KH (carbonate hardness)
KH is the water's resistance to pH changes, its buffering capacity. With high KH, pH does not move easily; with low KH, it swings more easily. In Caridina tanks KH is kept near zero and the active substrate stabilizes pH. In Neocaridina tanks a moderate KH helps keep pH steady.
Products that raise KH usually raise pH too, which is why KH buffers are not used in Caridina tanks. In a Neocaridina tank, very low KH can let pH swing during the day. If you use RO water, test KH regularly.
TDS (total dissolved solids)
TDS is the total amount of dissolved substances in the water, in ppm (parts per million, the same as mg/L). TDS meters are cheap and practical, especially when remineralizing RO water. But TDS tells you how much is dissolved, not what. Use it alongside GH and KH tests, not instead of them. TDS creeping up over time is a good sign that waste is accumulating; plan a water change.
If you use tap water, its TDS can vary between cities and even between seasons, so check regularly rather than trusting a single reading.
Temperature
Temperature directly drives shrimp metabolism. Warmer water holds less oxygen and shrimp age faster. Caridina are more sensitive to heat than Neocaridina. Keep the tank out of direct sunlight; small tanks follow room temperature quickly. Temperature swings are as stressful as high temperatures.
Ammonia, nitrite and nitrate
Leftover food and waste turn into ammonia. In a mature tank, bacteria convert ammonia to nitrite and then to much less harmful nitrate. In a healthy shrimp tank ammonia and nitrite must be zero. Nitrate is kept low with water changes and plants; a common target is below 20 mg/L. See the tank cycling guide.
If ammonia or nitrite rises, find the source first: overfeeding, a dead shrimp, a clogged filter or too little biological filtration. Change water gradually, and never rinse filter media under the tap; it kills the beneficial bacteria. If your tap water contains chlorine or chloramine, always use a water conditioner.
Step by step: dialing in your water
- Know your source water: tap or RO? Start by testing your tap water's TDS, GH and KH.
- Cycle the tank: no shrimp until ammonia and nitrite are zero.
- Pick target values: choose a range from the table for Neocaridina or Caridina and stay in it.
- If you use RO water, remineralize it: add mineral to the water-change water and check with a TDS meter.
- Test regularly: several times a week in a new tank, once a week in an established one for pH, GH, KH, TDS and temperature.
- Keep changes small: change a small portion of the tank volume each week.
- Keep notes: dates, values and anything you did; the record helps you spot problems early.
How to test
- Liquid drop tests are more reliable than test strips and are available separately for pH, GH, KH, ammonia, nitrite and nitrate.
- A TDS meter is almost essential, especially for Caridina and for preparing RO water.
- A thermometer is simple, but it is the tool you will check most often.
- Writing down results shows you the trend, which matters more than any single reading.
Watch test kit expiry dates. If a result is very different from what you expected, repeat it or confirm it with another test.
Common mistakes and how to avoid them
- Focusing on one value: fixing only pH can upset GH and KH. Look at the values as a whole.
- Sudden large water changes: shrimp are sensitive to sudden change; keep changes small and regular.
- Rinsing the filter under the tap: it kills beneficial bacteria and can lead to ammonia spikes.
- Overfeeding: it fouls the water quickly. Feed only what shrimp finish in a short time.
- Using chemicals carelessly: use pH reducers or hardness boosters gradually and as directed; avoid copper-based medications.
- Rushing a new tank: shrimp added before the cycle is complete are exposed to ammonia and nitrite.
Symptoms and possible causes
| Observation | Possible cause | Check first |
|---|---|---|
| Failed molts, white ring | Unsuitable GH or a sudden change | GH and KH, recent water changes |
| No appetite, hiding | Ammonia/nitrite spike, heat stress | Ammonia, nitrite and temperature |
| Mass deaths | Chlorine, copper, medication, sudden parameter change | Water source, products used, recent changes |
This table is a checklist, not a diagnosis. For more, see the guide on why shrimp die.
Tips for beginners
Keep your first tank simple: easy plants, a plain substrate and a reliable filter. Neocaridina are much more forgiving to start with. Do not add shrimp before the cycle is complete, and test often in the first weeks afterwards. If you use tap water, never skip the water conditioner. In shrimp keeping, patience is worth more than the best equipment.
Tips for experienced keepers
In Caridina tanks, active substrate loses its buffering power over time; a slow rise in pH is the sign. Remineralizing RO water in batches and checking each batch with a TDS meter gives more consistent results. Bringing new water to tank temperature and adding it slowly prevents sudden GH and temperature jumps. If you run several tanks, keep separate records for each.
Frequently asked questions
What pH should a shrimp tank have?
The commonly accepted range is 6.5–8.0 for Neocaridina and 5.8–6.8 for Caridina (Crystal/Bee). What matters is staying stable within the range you choose.
What should I do if GH is low?
Raise it gradually with a shrimp mineral. Add the mineral to your water-change water, not directly to the tank, and check GH and TDS afterwards.
If TDS is high, should I change all the water?
No. Gradual water changes are usually enough; a full change causes a sudden parameter swing. Look at your feeding and top-off habits to find the source; topping off evaporation with RO water stops TDS from building up.
Is tap water suitable for shrimp?
It depends on where you live. Find out whether it contains chlorine or chloramine and use a water conditioner. Test GH, KH and TDS to see whether it fits your target range; if not, RO water with minerals is a more predictable solution.
Why must ammonia and nitrite be zero?
Both are toxic to shrimp. In a mature tank, bacteria convert them to nitrate. If you measure either, do a small water change and find the source.
How often should I test?
Several times a week in a new tank and once a week in an established one is usually enough. During cycling, or whenever something seems off, test ammonia and nitrite more often.
The values and advice in this guide reflect what is widely accepted in the shrimp hobby. They can vary with the line, your water and the breeder your shrimp came from. Make changes to your tank in small steps.