Mastering Freshwater Aquarium Ecosystems
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Adjusting Water Chemistry (Cont.)

Several aquarium product manufacturers make pH increasers with different formulated ratios of chemicals, depending on the type of freshwater fish you are trying to keep. The chemical ratios in these products are used to target a specific pH. Follow the manufacturer's instructions on how much to add.

The pH can be lowered by adding sodium biphosphate, sodium bisulfate, or a pH decreaser from many of the aquarium product manufacturers, but it is not the recommended method. Using chemicals to lower the pH can have an undesirable effect on the aquarium ecosystem. Higher than desirable pH is more often the result of hard alkaline water, and using soft water in the aquarium will normally solve the issue. Using soft water and sphagnum peat moss is the choice of many advanced soft water fish breeders that need the acid water conditions for optimal reproduction.

How to Make Hard Water Soft

Fish that come from soft acidic water conditions in the wild will often benefit from the same conditions in the aquarium. Often fish that come from soft acidic water will be easier to breed and have higher fertility rate if provided with similar water in the aquarium. Some examples of soft acidic water conditions can be found in the Rio Negro in Brazil, Rio Orinoco in Colombia and Venezuela, and Lake Mai-Ndombe in Congo. These bodies of water often have a pH of 4.0 to 5.5 and almost no measurable hardness.

Kent RO/DI Unit

Kent Marine's "Deluxe Maxxima" RO/DI system with a built in TDS meter is an very good system you can use to make your tap water soft. It also makes excellent drinking water. Photo from Kent Marine.

When you make your water soft, you are not just trying to remove calcium and magnesium, but also alkalinity to reduce the TDS. There are a few ways you can make your tap water soft, reverse osmosis (RO) filtration, deionization (DI) filtration, and ion exchanger. The goal of using a water softener is ultimately to reduce the TDS. A TDS meter is good tool to have on hand to determine how soft the water is after it has been filtered and also lets you know when your filter needs maintenance.

Reverse osmosis filtration systems are connected to your tap water faucet or teed into the cold water supply. Cold water is passed through a micron filter, carbon filter and thin film composite (TFC) membrane. The TFC membrane removes about 95% of the TDS from the tap water. Typically, for every four gallons (15.2 l) of water that passes through the filter only one gallon (3.8 l) is collected. The unit has two lines coming out, one for wastewater, and the other goes to a collection container. Many hobbyist use a plastic trash can as a collection container. When you set up a RO system for the first time, check the TDS of the collection water. Note the TDS reading and then check periodically. When the TDS reading is higher than desirable, it is then time to change the membrane. The carbon filter and micron filter should be changed every six months.

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