Recommendations for Soft and / or RO Water

[jdsolo]

I am having a water softener installed in a few weeks. In addition, I am also having a RO unit installed in my kitchen sink.

My current water supply is in the 200 - 400 ppm TDS range.

My question is on which new water supply I should be using. Soft water or RO water. I don't have live plants. Tank is 20 gallon.

I'm guessing the RO would be the best choice, but not sure if it is taking out something the fish would need.

Thanks,

John

 

[Tim Bo]

Water softeners do indeed soften water, however, they do not reduce TDS levels. Salt-exchange resins work by replacing calcium and magnesium ions with sodium or potassium ions. A standard GH and KH test kit will show that the water is softer but a TDS meter may show an even larger increase in TDS levels. As far as I understand, water softeners use i.e. two sodium ions to 'eliminate' one calcium or magnesium ion. For this reason, I would go with RO water, but mix it with some tap water if you need to ensure a KH level that keeps you pH stable. RO water is also prettey much stripped of metals and other salts so you will have to add back the minerals that are stripped away which the fish need
Are you planning on breeding low-TDS (low pH) fish? Plants will not dislike hard water IMHO and can do fine.