I second testing the water with a new/different kit. I pretty much only trust SeaChem and Salifert for SW
water should test at or below 7.0pH if the RO
membrane is still functional. The DI
stage helps remove phosphates and organics.
Here's a way you can test though...what's the carbonate/Kh
/alkalinity of the new RO
water should be no more than 1dKh, ideally undetectable levels. if you read no Kh
, but a high pH, its likely your kit is bad. if you have lots of Kh
, then your RO
water isn't worth buying because its as hard as tap water.