fuge pump question


New member
iIhave a HOB refugium that I bought as a kit on ebay. I have had it for over a year and it has worked great. I started to notice the water flow has really diminished lately and tried cleaning the powerhead to no avail. It came with a small cheap rio pump and I want to replace it. Any ideas on what pump/ size, how many GPH etc to get. The fuge is approx 20" long, 4 " wide and 12" deep and holds about 3 gal water.
Thanks in advance.