Houdini Cyano algae - thoughts

[carriej]

Hi there,

I have been checking, and nitrates are currently reading 0 (even on the low scale) and phosphates are either 0-.25... The color is too close for me to tell. The tank is about 14 months old, 130 gallon tank with a 30 gallon sump, and a light biolode of only 7 small fish.

My biggest thing is it disappears! Is this normal for it to completely wipe itself out each day only to return? I was concerned it might be fluctuating alk, but each time I test alk it remains consistent at around 9dkh