Crystal Black Shrimp are often described with a list of numbers, but successful husbandry depends on understanding what those numbers represent. GH, KH, TDS, pH, and temperature interact with one another, and a stable system inside a practical range is safer than a tank that is constantly adjusted toward one ideal point. The best benchmarks are therefore both numerical and behavioral: healthy molts, active grazing, berried females, and consistent shrimplet survival should agree with the test kit.
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SUA Research Note: The current Shrimp Up Aquatics product guidance is pH 6.2–6.9, GH 4–6, KH 0–2, TDS 90–120 ppm, temperature 68–74°F, ammonia 0, and nitrite 0. These values are the operating range used throughout this guide.
pH: 6.2–6.9
pH describes hydrogen ion activity and tells you how acidic or alkaline the water is. In Crystal Black systems, pH is usually influenced by low KH, active soil, gas exchange, and dissolved organic compounds.
Do not force pH into range with sudden acid dosing. A stable substrate-and-source-water system is much safer than repeated chemical correction.
GH: 4–6
General hardness is the most useful routine measure of the calcium and magnesium present in soft-water shrimp systems. Crystal Blacks need those minerals for normal ion regulation and molting even though the total hardness remains relatively low.
GH-only remineralizers are useful because they raise calcium and magnesium without intentionally increasing carbonate hardness.
KH: 0–2
Carbonate hardness describes the buffering contribution of carbonate and bicarbonate. Keeping KH low allows active soil to maintain a gently acidic pH.
Low KH is intentional, but it also means you should avoid random alkalinity corrections. Stability comes from the whole system rather than from a large carbonate reserve.
TDS: 90–120 ppm
TDS is a useful consistency metric because it shows whether the total dissolved content is changing. It is not a substitute for GH, KH, nitrate, or other specific tests.
A TDS meter is especially useful when mixing RO/DI water. If the same remineralizer dose repeatedly produces the same GH and TDS, you have a reproducible recipe.
Temperature: 68–74°F
Crystal Blacks generally do well in stable cool-to-moderate temperatures. Avoid unnecessary heat. Warmer water increases metabolism and lowers oxygen solubility.
Temperature swings can be more stressful than a steady value near one end of the range. Match replacement water carefully during large seasonal changes.
Ammonia and Nitrite: Zero
Both should remain at zero in a mature aquarium. Detectable ammonia or nitrite means the biological system is immature, overloaded, disturbed, or failing.
Do not use sensitive Crystal Blacks to test whether a new tank is cycled. Establish the nitrogen cycle first and give the aquarium time to mature biologically.
Nitrate: Manage the Trend
There is no single magical nitrate number that defines success, but rising nitrate usually reflects increasing nutrient load. A stable breeding system should not be allowed to accumulate waste indefinitely.
Control nitrate through feeding discipline, plant growth, water changes, and appropriate stocking density. A slow upward trend is a maintenance signal even when the shrimp still appear normal.
Why Stability Beats Precision
A tank at GH 5 and TDS 112 that behaves consistently week after week is more useful than a tank oscillating between 95 and 125 ppm because the keeper is constantly correcting it.
Every adjustment changes osmotic conditions. Make changes only when the trend or the animals give you a reason.
How to Test Replacement Water
Prepare RO/DI water in a separate container, add remineralizer, circulate, and test GH and TDS before the water reaches the aquarium. Match temperature as well.
This prevents the aquarium from becoming the mixing vessel and keeps concentrated mineral powder away from livestock.
How Often to Test the Tank
Test more frequently during setup, cycling, substrate changes, or unexplained behavior. Once the tank is stable, routine spot checks and trend logging are usually sufficient.
The purpose of testing is to detect meaningful change, not to produce daily data with no action threshold.
TDS Creep
TDS can rise slowly when evaporation is topped off with remineralized water, when fertilizers and food add dissolved material, or when water changes are too small for the system's nutrient load.
Top evaporation with pure RO/DI water. Minerals remain behind when water evaporates, so adding more mineral during top-off compounds the dissolved load.
Why One Parameter Cannot Diagnose the Tank
A normal TDS does not prove that GH is correct, and a correct GH does not prove that ammonia is zero. Each test answers a different question.
Use several measurements together when troubleshooting. For example, a sudden TDS rise after a water change may point toward mixing error, while normal TDS with ammonia present points toward a biological-filtration problem instead.
Reading Shrimp Behavior
Active grazing, normal molts, berried females, and juveniles at multiple sizes are practical signs that the chemistry is working. Sudden hiding, surface gathering, failed molts, or multiple deaths deserve investigation.
Use behavior to decide when to look deeper, then use tests to narrow the cause. Good husbandry combines observation with measurement.
Related Crystal Black Guides
Comprehensive Crystal Black Care Guide • Neocaridina vs. Caridina Water • Active Soil & pH Buffering • RO/DI Remineralization • Soft-Water Breeding Rack
Frequently Asked Questions
What is the ideal TDS for Crystal Black Shrimp?
Shrimp Up Aquatics currently recommends approximately 90–120 ppm.
What GH should I use?
A practical target is GH 4–6.
What KH should I use?
The current recommended range is KH 0–2.
Is pH 7 too high?
It is above the current Shrimp Up Aquatics target range of 6.2–6.9 for this line.
Should I adjust TDS every day?
No. Use TDS to monitor trends and consistency rather than constantly manipulating the aquarium.
What matters more, exact numbers or stability?
Stability within an appropriate range is usually more important than chasing one exact value.
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Sources & Further Reading
- Freshwater ion regulation and osmoregulation research
- Osmoregulatory patterns in decapod crustaceans
- Calcium regulation during the crustacean molt cycle
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