Back in the day I had a basement system and a dedicated tank growing cheato. It worked really well. But I would not grow cheato in the sump. Too messy because of the lighting. I like a clean sump.
When dosing carbon cyano is part of the game. This happens when the phosphate is dropped to zero. Dial back on the dosing the cyano almost always disappear for me. My tank is ultra low in nutrients now without dosing and it also has cyano from time to time. just have to increase feeding. When carbon dosing, always test for phosphate and nitrate levels weekly and adjust as needed.
When dosing carbon cyano is part of the game. This happens when the phosphate is dropped to zero. Dial back on the dosing the cyano almost always disappear for me. My tank is ultra low in nutrients now without dosing and it also has cyano from time to time. just have to increase feeding. When carbon dosing, always test for phosphate and nitrate levels weekly and adjust as needed.