I've built a 40 gallon reef tank, and after reading some posts on various salt water community boards, decided to try and build an algae scrubber. My original intent was to convert the AquaClear to a HOB refugium. I've done one before on a 37 gallon reef tank, with great success. This tank, however, is going to be mostly corals and just a very few fish. I've also put a lot more live and dry rock in this tank, a little over 80 lbs. I've provided a good sized rubble pile in-tank, and have observed copepods and other critters hanging out there, so I thought I'd attempt an upflow algae scrubber conversion instead. Actually pretty simple, I think. Took the media basket and RTV'd 4 red LED tubes in place so they shine on both sides of the plastic grid. I'm not sure I'm going to keep these LED's. I'm probably going to DIY an LED array if this works out. I took a surplus glass top rear filler strip and cut it up for the channel to hold the grid in place as well as a strip to stiffen the top and bottom of the grid. Grid is standard Hobby Lobby stuff. I used 40 grit sandpaper in an orbital sander to rough up the grid. An air stone was RTV'd in place so the bubbles collect on the slightly angled screen. No permanent modifications have been done to the AquaClear HOB in creating this scrubber. Fired it up yesterday, and I'm very happy with the bubble interaction with the grid. Lots of bubbles stick to it, and the distribution is pretty good. Get a few bubbles through to the tank, but they dissipate at the surface. I''ll post some photos later today. I'm curious if anyone has attempted the conversion of a HOB filter, and if so, how successful was it? I found one thread where someone had done a fairly crude conversion of an AQ 70 using just a couple of plastic clips to hold the screen across the top of the filter, and a desk lamp for illumination.........