Check the nitrates and phospahtes both in your tank and from your water source. If you have a TDS
meter, check that from your water source as well. If you are reading nitrates above 20ppm in the tank, you need to get ready for frequent water changes. If you are reading anything other than 0 from the water source, you need a new water source. If you are reading phosphates in the tank, get ready for water changes. If you have phospates or a TDS
reading above 0 from the water source, get a new water source.
Next, look at your flow pattern. Cyano
tends to like low flow. The skimmer does (or I guess did) help with some of these issues as well.
Unfortunately, nothing really eats it in any noticable quantity.
How long are your lights on? If it's more than 10 hours, cut it back. This won't eliminate it by itself, but it can help.
As carried said, your best bet to remove is to siphon out during partial water changes. You do want to make sure you aren't fertilizing it with high nitrates or phosphates. You can also try adding GFO
in the filter loop to absorb some phospates as well. Many times the cyano
is absorbing it as fast as it is produced, plus the phosphate kit really only measures inorganic phosphates which is supposedly as little as 2% of the total.