Gear guide

TDS, GH and KH test kits for shrimp tanks

By the Shrimp Tank Hub editorsUpdated Oct 21, 2026Research-based

Research-based, not hands-on. We haven't tested these products ourselves. This guide compiles manufacturer-published specs and recurring owner reports (e.g. r/shrimptank, 2024–2026). Specs checked October 2026 and may change. How we research

Shrimp molt to grow, and successful molts depend on minerals in the water. That makes GH (general hardness: calcium and magnesium) and KH (carbonate hardness: buffering) the two numbers shrimp keepers test most, with a TDS meter as a quick daily check. Here is what each tool measures, according to its maker, and where owners say it falls short. We have not lab-tested these kits ourselves.

Tool	Measures	How it reads	Strengths	Limits
API GH & KH Test Kit	GH and KH	Liquid titration: count drops in a 5 ml sample until the color changes; 1 drop = 1 degree	No upper limit; widely recommended by owners over strips	1-degree resolution is coarse for very soft Caridina water; easy to lose count
HM Digital TDS-3	Total dissolved solids	Digital, 0–9990 ppm, 1 ppm resolution under 1000	Fast; ±2% accuracy (0–5000 ppm) per maker; automatic temperature compensation	Doesn't tell you which minerals are present
sera GH test / KH test	GH or KH (sold separately)	Liquid drop test	Common in Europe; includes syringe and chart	Same 1-degree drop resolution as API
Test strips (multi-parameter)	GH, KH, pH and more	Color match	Cheap and quick	Owners and reviewers repeatedly report vague readings and capped ranges; not ideal for shrimp

Why TDS isn't enough on its own

A TDS meter reports a single number for everything dissolved. As Shrimp Science points out, 107 ppm could be the right GH for bee shrimp, or it could be almost all carbonate with zero GH, which would cause failed molts. TDS is most useful as a stability check after you've confirmed GH and KH, and it works best with remineralized RO water, where you know what you added.

Typical targets

Commonly cited hobby ranges, not hard rules:

Neocaridina: GH about 6–8, KH about 2–6, TDS roughly 150–300 ppm.
Caridina (bee shrimp): GH about 4–6, KH 0–1, TDS roughly 100–160 ppm, usually on active soil with RO water.

Key caveat: drop tests are only as good as your count. Owners recommend testing over a white background, inverting the tube after every drop, and using a tally counter if you have hard water.

A simple routine

Test GH and KH of your source water once, and again whenever your water supply changes.
Test the tank's GH and KH weekly while it settles, then monthly.
Check TDS at every water change; a sudden jump means something changed.

Keep a log so you notice slow drift. Our printable water parameter log is designed for exactly this.

Our take

The API GH & KH liquid kit plus an inexpensive TDS pen like the HM Digital TDS-3 is the combination owners recommend most often. Skip strips for shrimp.

Sources: API GH & KH Test Kit instruction leaflet; HM Digital TDS-3 specification page; sera GH test product page; Shrimp Science, "TDS for shrimp tanks"; Modest Fish test kit comparison (2024); r/shrimptank discussion (2024–2026). Checked October 2026.