Over time you will develop algae wherever there is light and saltwater combined. Not a big issue, as cleaning algae is part of routine maintenance. However, I try to cover things as much as I can within the cabinet to keep maintenance to a minimum. As an example, I have a dedicated 20 gallon refugium under the stand beside the 30 gallon sump. I cover the light so nothing spills outside of the refugium, and even cover the sides of the refugium tank. Another area you can do this is the overflow, IF you have an overflow. I cover the top of the overflow with a black opaque roof. In 3 years, there is no algae in the sump adjacent to the dedicated refugium, nor in the overflows, no maintenance at all needed.
