TDS 50ppm

[Chewie]

Checked water from tap with tds meter. (I have another for sale in classifieds) It is 50 ppm. I am wondering if this is low enough to use as regular water change stock for my reef tank. I currently am buying ro/di at $3.75 / 5g for all w/c and top up. It is reading at 12ppm. I do know the lower the better but hoping to save a few bucks (use about $50 worth every two weeks. Have 2 100g tanks. 20% w/c bi weekly and 10g in top offs for both tanks.) I have considered a ro/di unit but they are expensive and worried my watet bill will go up.

[George]

50ppm is a little bit high for reef. Your store purchase ro/di water has similar TDS reading to my tab water, which is around low teen. After RO/DI, I have 0 TDS. You should look into a ro/di unit if you are serious about reef. If cost is a concern, look for a used one, but make sure the used filters are still good. The most expensive parts are the filters.