Hey Bud, Hope you're doing well. Bit of a dilemma I have. I think my scrubber is a little bit too efficient as I believe (and I could be completely wrong on this) I don't see much growth and wondering if this could be dodo with low phosphates? It's a wild guess as I've done a ATI ICP test (see below) and apart from metals in water column (still to be located as checked everything in sump/tank and water from RO machine also checks out OK) Tank build is a 5 x 2 x 2 with mixture of SPS/LPA and softies and only homing 4 fish and CUC so bioload is light. Filtration is BK 180Slim and Turbo LED HF rev 4 scrubber Dosing regime is ATO Essentials 123 @ 72ml per day per regent. Feeding is 2 frozen cubes once lunch and sprinkle of fish food grans in evening. As i want to increase the PO4, would a mixture of dimming down the lights and also feed more help? As you can see below, the algae in scrubber is good and green. I understand that there could be a number of causes for my PO4 depletion but only can see the great scrubber.