Water parameters and RO water for Caridina shrimp: a complete guide

Water parameters and RO water for Caridina shrimp: a complete guide

Water quality is one of the biggest success factors in keeping and breeding Caridina shrimp. The exact numbers differ by species and line, but the principle is always the same: stable, clean water with the right minerals beats constant chasing of a perfect number.

Part 1: the basics

Why water parameters matter

Many popular Caridina shrimp, especially Bee, Crystal and Taiwan Bee lines, are kept in soft, mineral-controlled water. When the water is too hard, too unstable or too different from the water they were bred in, shrimp can become stressed, molt poorly, stop breeding or die suddenly.

The goal is not to create laboratory-perfect water. The goal is to create water that is predictable, repeatable and suitable for the shrimp line you keep.

What is RO water?

RO water, short for reverse osmosis water, is water that has passed through a membrane that removes most minerals and contaminants. A DI stage can remove the remaining dissolved ions, often producing water close to 0 TDS. This gives you a clean starting point.

Pure RO water is not safe as aquarium water on its own. Shrimp need minerals for molting, muscle function, eggs and osmoregulation. You must remineralize RO water before using it for water changes.

Why use RO water for Caridina shrimp?

• You start with a clean baseline instead of unknown tap-water chemistry.
• You control which minerals enter the aquarium.
• You avoid many tap-water issues such as high KH, heavy metals, chlorine/chloramine residues or seasonal variation.
• You can make the same water every time, which makes stability much easier.

The three core values: GH, KH and TDS

GH: general hardness

GH measures mainly calcium and magnesium. These minerals are essential for a strong new shell after molting and for normal body function. For many Bee and Taiwan Bee-style Caridina, a common target is GH 4-6. Some Tiger lines tolerate a little more.

Too little GH can cause weak molts. Too much GH can make molting harder and may indicate water that is not suitable for soft-water lines.

KH: carbonate hardness

KH measures carbonates and bicarbonates. These act as a pH buffer. For Neocaridina this is useful, but for soft-water Caridina it often works against the desired low pH.

Bee, Crystal and Taiwan Bee-style shrimp are commonly kept at KH 0-1 with an active substrate that buffers pH. Do not use GH/KH+ salts for these lines unless you have a clear reason and know what your breeder used.

TDS: total dissolved solids

TDS measures the total amount of dissolved material in the water. It is a quick check, not a full water test. For many soft-water Caridina, a practical range is roughly 100-200 ppm, with high-grade Taiwan Bee lines often kept near the lower end.

Use TDS as a repeatability tool: if your chosen GH+ mineral gives GH 5 at 130 ppm, you can use 130 ppm as a quick target for future water changes. This only works if you use the same mineral product and the same meter.

A simple starting process

1. Produce or buy RO water. Test it before use. Good RO water should usually be close to 0-10 ppm TDS.
2. Remineralize with the right product. For Bee, Crystal and Taiwan Bee-style shrimp, use GH+ rather than GH/KH+.
3. Measure GH, KH and TDS. TDS is fast, but GH and KH drop tests tell you what is actually happening.
4. Match temperature. New water should be close to aquarium temperature before the water change.
5. Add water slowly. Sudden changes in pH, TDS or temperature can cause stress or shock.

For water changes, use remineralized RO water. For topping up evaporation, use pure RO water, because only water evaporates; minerals stay behind.

Part 2: deeper water chemistry

Osmoregulation in shrimp

Freshwater shrimp must constantly regulate the balance of water and salts in their bodies. Their body fluids contain more dissolved salts than the surrounding water, so water naturally wants to move into the shrimp. The shrimp uses its gills and other systems to take up ions and remove excess water.

When the outside water changes too quickly, or when mineral levels are unsuitable, this system has to work harder. That is one reason sudden changes can be more dangerous than slightly imperfect but stable parameters.

Why Caridina are often less forgiving than Neocaridina

Neocaridina davidi lines are famous for tolerating a broad range of aquarium conditions. Many Caridina lines, especially Bee and Taiwan Bee types, are less forgiving because they are kept and selected in narrower, softer water conditions.

That does not mean every Caridina needs identical water. Tigers, Amanos, Sulawesi shrimp and Bee shrimp are very different. Always match the species and, if possible, the breeder's water values.

Remineralization: what the minerals do

• Calcium supports the exoskeleton, molting, muscle function and eggs.
• Magnesium supports enzyme processes, metabolism and shell formation alongside calcium.
• Potassium helps nerve and muscle function and contributes to cellular balance.
• Sodium plays a role in osmoregulation, but ordinary table salt is not a shrimp remineralizer.

GH+ versus GH/KH+

GH+ raises general hardness without adding significant carbonate buffer. This is the standard choice for many soft-water Caridina tanks with active substrate.

GH/KH+ raises both general hardness and carbonate hardness. This is useful for Neocaridina and some setups that need a stronger pH buffer, but it is usually the wrong choice for Bee and Taiwan Bee-style soft-water tanks.

How GH, KH and TDS relate

GH, KH and TDS are connected but not interchangeable. One degree of GH or KH contributes roughly 17.8 ppm to dissolved solids, but commercial minerals also contain other ions. Nitrate, fertilizers and other dissolved substances also increase TDS.

This is why a rising TDS in an established tank can mean more than minerals. It can also signal nitrate buildup, evaporation without proper top-off, overfeeding or accumulating waste.

Practical target ranges by shrimp type

Taiwan Bee and high-grade Caridina lines

• pH: often 5.6-6.6, depending on substrate and line
• GH: 4-6
• KH: 0-1
• TDS: often 100-150 ppm
• Temperature: usually 18-23 degrees Celsius

Crystal Red and Crystal Black shrimp

• pH: often below 6.5
• GH: 4-6
• KH: 0-2
• TDS: roughly 120-180 ppm
• Temperature: usually 18-24 degrees Celsius

Tiger shrimp

Tiger lines are often a little more flexible than Taiwan Bee lines. Many do well in soft to medium-soft water, but exact targets depend on the line and whether it has been crossed or adapted over generations.

Common mistakes

• Using pure RO water without remineralizing it.
• Using GH/KH+ in a Bee shrimp tank that should run on GH+ and active substrate.
• Making large water changes with different pH, TDS or temperature.
• Chasing pH with chemicals instead of fixing KH, substrate or source water.
• Letting TDS creep upward through evaporation and topping up with mineralized water.
• Adding limestone, shells or carbonate-rich rock to a soft-water Caridina tank.
• Buying shrimp without asking what water values they were bred in.

Troubleshooting quick reference

Problem	Likely direction to check	What to do
Failed molts	GH too low or too high, unstable minerals	Test GH, check remineralization and change water more gradually.
White ring after changes	Parameter swing	Use smaller, slower water changes and match TDS/temperature.
TDS keeps rising	Evaporation, nitrate, waste or overfeeding	Top off with pure RO, reduce feeding and test nitrate.
pH remains too high	KH source, exhausted soil or carbonate rock	Test KH, check hardscape and consider replacing active substrate.
No breeding	Stress, unstable water, poor biofilm or unsuitable line conditions	Stabilize for several weeks and improve maturity before changing more.

The real goal: stable ecosystems, not chemical perfection

The best shrimp tanks are stable ecosystems. Good numbers help, but they do not replace a mature filter, biofilm, microfauna, calm maintenance and observation.

A shrimp raised at 150 ppm TDS can often adapt to 170 ppm. It cannot adapt well to a sudden jump from 110 to 190 ppm in one afternoon. Gradual change is the key.

Focus on stable parameters, mature biology, biofilm, clean food habits and patience. Combine that with the right RO and remineralization routine, and you have a strong foundation for healthy, breeding Caridina shrimp.