TheFritz General Hardness (GH) Test Kitmeasures the total calcium and magnesium content of your freshwater aquarium — a critical parameter for fish, shrimp, and live plant health. GH (“general hardness”) tells you whether your water has enough dissolved minerals for soft-water species like tetras, discus, and rams, or whether it’s hard enough for livebearers, African cichlids, and shrimp.
Pair this single-parameter kit with the Fritz Master Test Kit for full water-quality coverage, the Fritz Phosphate Test Kit for algae troubleshooting, or browse the full water testing collection.
Features
- Liquid drop-titration test for General Hardness (GH)
- Designed forfreshwater aquariums
- Simple count-the-drops procedure — no color cards required
- Each drop = 1 dGH (degree of General Hardness)
- Long shelf life when stored properly
- Made by Fritz Aquatics — a trusted name in aquarium chemistry
How to Test
- Rinse the test vial with clean aquarium water.
- Fill the vial to the indicated line with sample water.
- Add the reagent one drop at a time, gently swirling the vial after each drop.
- Count the drops until the color changes from orange/red to green.
- The number of drops added equals your GH in degrees (1 drop = 1 dGH ≈ 17.9 ppm).
Always follow the printed kit instructions for the most accurate procedure and timing.
Target GH Ranges
- Soft-water community (tetras, rasboras, discus, rams, gouramis):3 – 8 dGH (50 – 140 ppm)
- General community (most tropical fish):4 – 12 dGH (70 – 210 ppm)
- Livebearers (guppies, mollies, platies, swordtails):8 – 20 dGH (140 – 360 ppm)
- African cichlids (Lake Malawi/Tanganyika):10 – 18 dGH (180 – 320 ppm)
- Shrimp (Neocaridina):6 – 12 dGH (110 – 210 ppm)
- Caridina shrimp (Crystals, Tigers):4 – 6 dGH (70 – 110 ppm)
Specifications
| Brand | Fritz Aquatics |
| Tests | General Hardness (GH) — calcium + magnesium |
| Test Method | Liquid drop-titration (count drops) |
| Water Type | Freshwater |
| Resolution | 1 drop = 1 dGH (~17.9 ppm) |
| Kit Includes | Reagent bottle, test vial, instructions |
| Storage | Cool, dry place out of direct sunlight |
Recommended Pairings
- Fritz Master Test Kit — all-in-one liquid test kit for a full chemistry picture
- Fritz Phosphate Test Kit — track phosphate for algae control
- Fritz 6-in-1 Test Strips — quick daily-check companion to liquid kits
- Aquaforest Shrimp GH+ — raises GH for shrimp tanks running on RO/DI
- Hanna HI735 GH Checker — digital precision alternative
FAQ
What’s the difference between GH and KH?
GH (general hardness) measures dissolved calcium and magnesium. KH (carbonate hardness / alkalinity) measures bicarbonate buffer capacity. Both matter, but they describe different chemistry — and one doesn’t predict the other.
How often should I test GH?
Weekly if you keep livebearers, shrimp, or African cichlids — they’re sensitive to swings. Monthly is enough for soft-water community tanks once you know your tap or RO/DI baseline.
My GH is too low for shrimp. How do I raise it?
Add a remineralizer designed for shrimp, like Aquaforest Shrimp GH+. Avoid raising GH with crushed coral or aragonite — those raise KH and pH too, which most shrimp don’t want.
Can I use this in a saltwater tank?
No. GH testing is for freshwater only — saltwater uses calcium, magnesium, and alkalinity tests instead. For saltwater, see our saltwater collection.
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