Diagnose slow decline

[asylumdown]

Originally Posted by syncro

Another vote for the "too clean" theory, thanks Hazratty. I'll sell the haddoni (too demanding) then experiment with running less clean. On one hand, I am putting far more food into the system than I was before this decline. On the other, before the decline I was doing water changes once a month or less with the minimal bioload. In any case, I think it is worth experimenting with.

Titus, it could be diatoms. A quick search sounds like diatoms are brown and cyano is red. I'd guess this algae is more red than brown. If diatoms, let them run its course. If cyano, then nutrient problem?

I'm going to vote too clean as well. If you're deep sand bed is doing what it's supposed to, you should theoretically be at a really low nutrient level, and even though you've added fish, it doesn't sound like your bio-load is really all that high. And cyano is a tricky beast. It's presence does not necessarily mean you've got excess nutrients. It's a photosynthetic bacteria that is both an autotroph and a heterotroph and can survive in situations that lots of other things can't. I've always been really suspicious of the supposed causes of cyano, because if a lot of the 'common wisdom' about it was true, a simple course of chemi-clean shouldn't banish it forever from some people's tanks as it often seems to do. I have always thought of cyano more as an infection (it is a bacteria after all) than an algae.