Aquarium systems test kitr a new range of test kits from aquarium systems that accurately test your marine aquarium waterr seatests calcium test kit comprises approx 40 individual tests for calcium ca levels within the aquariumr calcium is used by many corals and invertebrates to grow shell and structure and levels can therefore become too low over time to allow growth to continue or will cause irregular growth patternsr ideal calcium levels are typically 400 to 500 mglitre