My refugium’s are not sumps, they are large hang on basket filters with chaeto where the filter media is supposed to go. Take that judge Judy. :0)
I rigged a cheap $5 double sponge filter to the intake, which is really just to keep the chaeto clean. It's an Aquaclear 70 HOB. The high flow vertically through the chaeto works extremely well, better than a regular sump type refugium IMO. The high flow keeps the chaeto pristine and I never have to turn it, only harvest half a couple times a month. This also provides enough flow and turnover for a 55 gallon tank, though it's currently on a 20Long. the 9 watt grow light is all that’s needed for the chaeto to grow like crazy and remove nitrates low even in an over-stocked tank.