Aquarium systems test kitr a new range of test kits from aquarium systems that accurately test your pondaquarium waterr test kit by aquarium systems for measuring the total hardness of your tropical or cold freshwater aquariumr comprises 2x 10ml gh indicator fluids the number of tests the kit will perform will vary according to hardness levelsr differing levels of water hardness gh will be required depending upon the type of fish being fish being kept your tank must be adpated to hard