Using A Britax Water Purifier For RO Water

Do you mean Brita filter?

I have a Brita filter jug and have tested everything I can in the water.

Comparing freshly run tapwater with freshly filtered water:

Tapwater - pH 7.2, GH 9, KH 3.5
Filtered    - pH <6,  GH 6, KH 0


Brita filters work be substituting hard minerals for soft, in this case they substitute calcium & magnesium (GH) with hydrogen ions - and pH is an upside down measure of the amount of hydrogen ions, the more there are the lower the pH, which is why the filtered water's pH was off the bottom of the scale with the API tester. They must also substitute something for carbonate but I've not found out what yet.


So the answer is no, Brita filtered water is not a good substitute for RO water as it still has stuff dissolved in it, and it maybe stuff that is not good for fish.

OK, thanks Sue. It's not such a big problem, the Maidenhead Aquatics near me can sell me RO water and the cost isn't that prohibitive given the small amounts I'll need for my tank.
I just don't want the hassle of fitting an RO unit.