I have one of the above on a 60x38x30 and currently have it at the second lowest setting on a low tech. Problem is my rotala is getting covered in BGA. All the other plants are fine. I'm dosing my tank up to EI levels and keeping it aerated to provide as close to equilibrium levels of gases. So the only variable left to tinker with is the light. Just wondered what setting other users had it on a low tech. Any help appreciated. Thanks.