Do you need to add salt to an aquarium housing this male Labidochromis caeruleus? It depends on your tap water.

Do you need to add salt to an aquarium housing this male Labidochromis caeruleus? It depends on your tap water.

Q. Can you tell me a good way to measure African rift lake salt in my fish tank? I have checked around at numerous local pet shops and at the Tennessee Aquarium, but no one has given me a satisfactory answer about adding salt to african cichlid tanks. Everyone just tells me to follow the directions on the container. It seems to me if it is important enough to have this salt in the water, it should be equally important to make sure that I have added the right amount. Janet, Paragon.

A. The question you should be asking is not how to measure the concentration of rift lake salts in your aquarium, but rather, whether you need to add any at all. Both Lake Malawi and Lake Tanganyika have hard, alkaline water, reflecting their long histories as essentially closed drainage basins. Aquarists soon discovered that cichlids native to these lakes required comparable water conditions to do well in captivity. In some parts of North America, the municipal water supplies were too deficient in dissolved minerals to meet these requirements. A market thus developed for products that could be added to an aquarium to correct this problem. Before you purchase any of these products, however, you should first determine whether or not you need them. If you do not have one already, you should definitely purchase a good water hardness test kit. Take care that your kit allows you to test both general hardness (GH) and carbonate hardness (KH), because both of these measurements are useful in the present context. General hardness values in Lake Malawi range between 6 and 10 degrees on the German scale, abbreviated as DH. This works out to from 102.6 parts per million (ppm) to 171.0 ppm in absolute terms. Carbonate hardness values fall between 6 and 8 degrees DH, or 102.6 to 135.8 ppm. In captivity, Malawi cichlids seem to do well enough in somewhat softer water. General and carbonate hardness values of 5 degrees DH, or 85.5 ppm, represent safe base values for a Malawi cichlid tank. The waters of Lake Tanganyika are harder than those of Lake Malawi. General hardness values range from 9 to 12 degrees DH, or 153.9 to 205.2 ppm, carbonate hardness from 8 to 10 degrees DH. While I know hobbyists who have bred a number of Tanganyikan cichlids in water with GH and KH values as low as 5 degrees DH, 10 degrees DH represents a more prudent bottom line value for these fish. If your tap water falls within these values there is no need to add any supplementary mineral salts to your tank. Simply adding Philippine coral gravel to your tank’s substrate at a rate of  pounds per 20 gallons of water will provide a mineral reserve sufficient to keep hardness and pH values at acceptable levels.  gravel. If hardness values for your tap water fall below theirs threshold values, you will want to harden the water in your tanks. The simplest way to accomplish this is to use unadulterated Philippine coral gravel as the tank substrate. If this approach is not acceptable for technical or aesthetic reasons, you will want to make use of commercial salt mixes to raise hardness values. Measure the hardness values in the tank berfore and after you add salt. The only measurement that will reflect the total quantity of dissolved solids in your tank tater is electrical conductivity. However, your interest lies in those substances that directly affect the water hardness. Thus, the difference between the higher hardness values after adding salt mix and the previous values will tell you how many ppm of these biologically important substances you have put into solution. Just bear in mind that every time you make a water change, you are removing a certain quantity of these mineral additives from solution. You must thus add a quantity equal to that removed when you add new water to the tank in order to maintain stable conditions. For illustrative purposes, if you initially add 5 pounds of rift lake salt mix to a 30-gallons tank, you will need to add 2 pounds of mix every time to change 40 percent, or 12  gallons, of tank water. As these salt mixes are not inexpensive most rift lake cichlid keepers lose their enthusiasm for this sort of water chemistry very quickly and opt to replace their existing aquarium susbtrate with Philippine coral gravel. The investment may be substantial, but it very quickly pays for itself in lower ongoing maintenance costs and enhanced convenience.