So, what do you do if your tap or well water is hard but you have soft water fish? If you don'thave the soft water fish yet, reconsider. Otherwise, the best thing to do long term is to buy areverse osmosis system. Reverse osmosis or RO uses a membrane to extract the ions from waterto reduce the hardness. When the hardness goes down, the pH and alkalinity normally follow. RO water is similar in some ways to distilled water except that the filter has a limit to themembrane size so that some smaller things are still going to be in the RO water. RO water iscommonly used with discus tanks for example or to be mixed with hard water to bring it down toa useable level. RO systems are expensive initially.
Preparing tap water for fish tanks
I don’t think my tap water is safe for fish. I tested the pH out of the tap and it was 8.9 and my KH was almost non-existent. What can I do so that it won’t shock my fish? Should I treat with pH Down?
Will a fish die if it's put in tap water? - Quora
I am a beginner. I have a 40 gallon tank with four glo-fish and one platy. Chloramine is added to my city water. I can buy RO/DI water from my local pet store however it is a distance away from my home. So, would it be possible to use a water conditioner, such as Prime, to remove the chlorine and chloramine; would this make the water safe for the fish? Are these types of water conditioners effective at removing such chemicals from tap water? Thanks!
Not necessarily, but it's not a good start
Most people use tap water in their tanks; it is cheap and easyto use. Unfortunately (for aquarists), local water companies addchemicals to the water to make it safe to drink (e.g.,chlorine or chloramine to kill bacteria). More recently, concernabout water flowing through older lead pipes has caused some waterutilities to add pH-raising chemicals to the water (because lead dissolvesless readily in alkaline water). Consequently, tap water must bespecially treated before it can safely be used in fish tanks.Some people are interested in using rain water for theiraquaria. In this case, you need to consider the condition of the airand the condition that leaves the rain water in. Tap water has beenfiltered through soil and then processed to insure that it ispotable. Rainwater can carry pollutants which it has washed out of theair, as well as possible contaminants from tubing, gutters, piping,roofs, and other surfaces it has flowed through or over before gettingto your collection point - as well as risks of contamination in thecollection apparatus. Rainwater is also almost always lacking innecessary trace elements to keep the fish healthy, as well as thosenecessary to help the water maintain chemical balance.