We need to up our skim game, but have a strange limitation. Our sump is OVER our tank on a shelf and the max max max H available is 20" from bottom of sump to the ceiling. Our tank is a 125g mixed reef. Thus far, I've been unable to find anything that would work. While some models are right at 19.5-20", there's still no room to remove the skim mate cup. Any ideas?