Fritz General Hardness (GH) Test Kit | Liquid GH Water Test for Freshwater Aquariums

The Fritz General Hardness (GH) Test Kit measures 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 for freshwater 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

1. Rinse the test vial with clean aquarium water.
2. Fill the vial to the indicated line with sample water.
3. Add the reagent one drop at a time, gently swirling the vial after each drop.
4. Count the drops until the color changes from orange/red to green.
5. 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

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.