filtered "top-up" water?

[Perodogo]

Hey Fishdude!
Although I have RO hooked up in our main water system, I only use it for our own drinking purposes, although I'm starting to think that I should start using it.

I seem to be having a brown algae (diatom) problem which I could not get rid of. My Chevron tang has done an admirable job cleaning up most of it but I would like it to go away all together. Does anyone else have the same problem?? Is tap water the culprit??

Regards,
Rico