Chetomorpha macro algae is great for lowering PO4 and NO3. It does not go sexual like Caulerpa, so there is no need to worry about it releasing the nutrients back into the water, and it grows very fast. It will also, like LR, provide an area for pods, mini-stars, etc. to reproduce and live, boosting the pod numbers in the main. Lighting the fuge when the main lights are out may help reduce the PH drop at night. The cheato uses CO2 and releases O2.