What level should phosphates be at?
As close to zero as possible. You ahve two main objectives here...1. to identify and correct the source of the cyno and 2. to remove the exsisitng cycno from your tank. First, test for PO4
in both your tank water and your source water (used t changes and topp-offs). Make sure you are using a high quality RO
water. This is most likely the problem. PO4
can also be introduced into the tank by froozen foods. If you feed froozen, make sure you thaw it first and then rinse it in RO
water before adding it to the tank. Add another powerhead or two to the tank to create more flow. Cyno has a harder time getting a hold in hig current areas. Make sure there are no dead spots in the tank. Siphin as much of the cyno off of the subsrtate as you can. You can also try a product like Chemi-Clean to remove it. But if you have not corrected the source it will just come back. Good luck in the battle...Lando