People often ask what they can do to speed up the filtering after they've added a scrubber, at least until there scrubber "catches up" and fixes thing. Here are some things to consider:
Increase the lighting period in your display a few hours; this increases photosynthesis (filtering) of your corals, and of also of the periphyton on your rocks.
Feed less, or break your current feedings into smaller ones (don't feed all at once). This is because each burst of feeding generates lots of ammonia/urea by the fish, and lots of ammonia by the corals. When all that ammonia goes into the water at one time, it goes straight to your glass and rocks, and is absorbed by algae anywhere the algae can exist. A larger burst of ammonia will support more algae throughout your system, but by breaking your feedings up into more smaller feedings, the peak levels of ammonia in your water will be reduced before the ammonia can feed more nuisance algae.
Keep your sump vacuumed.
Start (or do more) water changes. Not the most effective in the world, and is costly and a hassle, but it will help some.
Start (or do more) GFO. This is more effective than water changes if you use a reactor, and much easier. If it causes your scrubber grow less, then use less GFO.
And speaking of the periphyton on your rocks, don't move any rocks or change any flow on them; keep everything the same and your natural periphyton filter will develop on your rocks in about a year and will help tremendously.
- C. Smith