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Is my well water with a salt filter safe for my aquarium fish?

Updated On September 23rd, 2025

Pet's info: Fish | Unknown - Fish

We are new to having aquariums, we really didn't realize so many things played a factor with the water. We currently have a 10 gallon tank but want to increase to a 29 gallon tank. We currently buy gallons of water but with the 29 gallon tank we really don't want to have to do that. We have well water with a salt filter. My levels from to tap was nitrate 10, nitrite 0, hardness 0, chlorine 0, alk 100, ph 7.. is my tap water safe even with the salt filter.

1 Answer

Most Helpful Answer

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Answered By Angel Alvarado, LVT

Licensed Veterinary Technician

Published on August 10th, 2018

Water softeners leave very little salt residue in the treated water. Most, not all, fish *should* do fine in softened water. Make sure you get species that does better in soft water. Use a hardness kit and monitor KH. This parameter is what can affect pH. You can set aside a gallon or two and test it after it has aged for 24-48 hours to confirm it is safe to use. Check the softener unit for a bypass valve. Some units will have one or you can get one installed. Taps/faucets outside may not be in line with the softener, so you can use water from there if necessary.

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