, it is the main "food" of cyno. Reduction through the use of PO4
sponges will help, but you need to find the source.
Overfeeding is a common cause. Also the use of tap water will feed the outbreak as well as other factors.
Us R/O water, if you already are, add the use of a deionizer to reduce PO4
in your source water.
Do frequent water changes with water low ir PO4
siphon of the "mats" of cyno, breaking it up will only spread it.
Do not over feed. Only feed as much as you fish will eat in a couple of minutes.
Add water movement to areas of low flow with the use of PH
's. Don't let it set up.
A productive skimmer will help. If your skimmer does not produce several cups of dark skimmage every week, consider an upgrade.
rediction is the key. I completely eliminated my cyno problem with the above.