Cannot get rid of cyano!

[MarkoD]

Originally Posted by Nate

You ask for advice as long as its what you want to hear. Do some water changes I bet your cyano goes away.

I maintain about 50 tanks in Calgary and tend to only get cyano in tanks with too low flow, tanks that have had persistent low kh, and tanks that dont get enough water changes. Water changes and increased flow have solved the problem Every time. And yes, it's at about the 8-14 month mark when you tend to see this problem
Build up.

Do you clean your gravel?

No I ask for advice and you suggested things I had already done. I vacuumed the gravel 5 times now and it always comes back 2-3 days later.

I only have 1-1.5 inches of sand anyway.

Since the cyano started I have done water changes with no improvement.

I've got alternate methods of nutrient reduction, which is why I don't do frequent water changes. I dose alk, calc, mag, strontium and iodine.