Do you test to determine when your GFO needs changing?

[Reefer Rob]

Originally Posted by Delphinus

What do other people notice about their tank with, versus without, GFO? Film algae on the glass? Water clarity? Etc.? Just wondering what people see, because I couldn't see a difference myself.

When I started using GFO a couple of years ago, a red carpet algae (that's what I called it) that I had on my rocks (and snails etc.) for a year at least just melted away over a period of weeks. I was dancing in front of my tank (not a pretty sight). Over the same period my Chaeto did the same... but that's OK, fair trade.

Now I just use it as a preventative measure. If I slack off I notice my rocks aren't as clean.