Shrimp water parameters

The table

What each number does

GH — general hardness

The calcium and magnesium content. This is the shell-building mineral supply, and it is the number that matters most, because a shrimp that cannot complete a molt dies during it. Too low and you get failed molts and the white band at the neck. Too high and molting becomes laboured in the other direction.

KH — carbonate hardness

The buffering capacity — how strongly the water resists pH change. Neocaridina benefit from some, because it holds pH steady. Caridina want essentially none, because their whole setup depends on an active soil pulling pH down, and KH fights it.

pH

Largely a consequence of KH and substrate rather than something you set directly. Do not chase it with pH-adjusting chemicals; fix KH and substrate and pH follows. A stable 7.6 is better than a 6.8 that moves.

TDS — total dissolved solids

Everything dissolved in the water, measured with a cheap meter. It will not tell you what is in the water, but it tells you instantly whether something has changed — which is exactly what shrimp react to. A TDS meter is the single most useful instrument a shrimp keeper can own.

Temperature

Warmer means faster metabolism, faster breeding and shorter lives. Cooler means slower everything and longer lives. Most San Diego rooms sit in range for Neocaridina without a heater; Caridina benefit from being kept at the cooler end, which in summer can mean a fan across the surface.

San Diego water specifically

Our tap is hard and it is chloraminated. Two consequences:

• Chloramine does not gas off. Leaving a bucket out overnight does nothing — that advice dates from when supplies used free chlorine. Use a conditioner that neutralises chloramine, every time, or filter it out with a carbon block rated for it.
• The hardness is an advantage for Neocaridina and a wall for Caridina. Cherry shrimp keepers here have it easier than almost anywhere. Crystal red keepers here have to build their water from RO, with no shortcuts.

Both stores test water free. Bring a sample in a clean container — and for a Caridina setup, bring your mixed RO-plus-remineralizer rather than tap, because that is the water that matters.

Changing water without killing anything

Shrimp react to the rate of change far more than to the values themselves. Practical rules:

• Small and frequent beats large and occasional. Ten to fifteen percent weekly is plenty for a lightly stocked shrimp tank.
• Match the replacement water's temperature and TDS to the tank. For Caridina, mix and measure before it goes anywhere near the shrimp.
• Add new water slowly — a slow drip or a trickle down the glass, not a bucket poured in.
• Drip acclimate new arrivals over an hour or more. See the drip acclimation guide.

The one rule that overrides all of these

Species pages: Neocaridina · Caridina · cherry · blue dream · crystal red · Amano.

Questions we get asked

What GH do shrimp need?

Neocaridina and Amano do best at GH 6 to 8 and tolerate up to about 12. Caridina such as crystal reds and taiwan bees want GH 4 to 6. GH is the calcium and magnesium content that shrimp build their shells from, which is why it is the most important single number.

Do I need a TDS meter for shrimp?

It is the most useful instrument a shrimp keeper can own. It does not tell you what is in the water, but it tells you immediately whether anything has changed — and rapid change in dissolved solids is what shrimp actually react to.

Is San Diego tap water good for shrimp?

For Neocaridina and Amano, yes — it is naturally in the right hardness range and needs only dechlorinating. For Caridina it is unusable, because it is hard and buffered where they need soft and acidic water built from RO.

Does chlorine evaporate out of tap water overnight?

Not in San Diego. The supply is chloraminated, and chloramine does not gas off the way free chlorine did. It has to be neutralised with a conditioner or removed with a suitable carbon block, every time.

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