Understanding TDS and GH for Shrimp Keeping
Two Numbers That Matter More Than You’d Think
Beyond the usual focus on pH and temperature, total dissolved solids (TDS) and general hardness (GH) play an outsized role in shrimp health, particularly for keepers working with RO water or more sensitive Caridina species. Understanding what these numbers actually measure helps prevent avoidable losses.
What TDS Actually Measures
TDS is a broad measurement of all dissolved minerals and compounds in your water, giving a quick snapshot of overall water “richness” without specifying exactly which minerals are present. It’s especially useful for tracking consistency over time and for remineralizing RO water to a target range suited to your specific shrimp species.
What GH Tells You
General hardness specifically measures calcium and magnesium content, both of which shrimp need directly for healthy exoskeleton development during molting. Water that’s too soft, without adequate remineralization, can lead to chronically failed or incomplete molts even if other parameters like pH appear perfectly fine.
The Relationship Between GH and KH
While GH measures calcium and magnesium, KH measures carbonate hardness, which buffers pH against sudden swings. A tank can have adequate GH for healthy molting but still experience unstable pH if KH is too low, making it worth tracking both numbers rather than focusing on just one in isolation.
Species-Specific Targets
Different shrimp species have evolved in very different natural water conditions, meaning target TDS and GH ranges vary considerably. Hardier Neocaridina varieties tolerate a wide range, while many Caridina species and specialty shrimp like Sulawesi varieties require more narrowly controlled mineral content to thrive long term and molt successfully.
Recording Baseline Numbers
Testing and recording your tap water’s baseline TDS and GH before any adjustments gives you a reliable reference point, making it much easier to replicate consistent remineralized water for future water changes rather than guessing each time.
Testing and Adjusting Safely
A dedicated TDS meter and a liquid GH test kit are worthwhile investments for anyone serious about shrimp keeping beyond the beginner stage. Adjustments should always happen gradually, since sudden swings in mineral content can shock a colony just as severely as an abrupt pH or temperature change, undoing weeks of stability in a single afternoon.
Buying With Your Water in Mind
Before ordering live shrimp for sale, testing your existing water’s TDS and GH and comparing it to your target species’ needs prevents the frustrating cycle of chasing symptoms without understanding the underlying mineral imbalance causing them.