my biggest complaint with these filters, is that infernal sucking noise... that I always thought was the protein skimmer... come to find out there are 2 slots, cut into the body of the filter in the waterfall return, SeaChem calls the "aerating return flow" it drives me crazy, if my tank is full, it’s reasonably quiet, but if the water level drops down about a 1/4 of an inch, I get this horrendous sucking noise... the skimmer slots could do the same thing, but the noise that bothers me most are the 2 slots cut in the discharge, the 2 slots to the left in the picture are open, the others are closed… those will be covered with silicone, & while I'm at it, I'll also silicone 1/2 to 3/4 of an inch of the very top of the 3 inch skimmer slots... next, there is a dial under the filter box, that the draw tube is half blocked, & you can adjust it to completely block the draw tube, so it only sucks from the slots at the bottom of the pump box, which is 6-7 inches from the top of the tank, and the skimmer slots at the top... I have no need for the pump, not sucking from the bottom ( perhaps it's there to keep from sucking up sand with earth eaters in the tank, or to provide more suction for floating big pleco poops??? ) my tanks that have sand in are tall tanks, so not a concern at this point... but my next tank will be a normal height sand tank, so I'll revisit this mod, on my next filters... I had issues with one pump squirting water out the top of the box, when the filter sponge got too plugged, will look at that later... I think a tighter fitting sponge, or thin sponge inserted along the box wall, will fix that... I think these are one of the best HOB filters out there, if it weren't for those 2 slots in the discharge… I wonder if it was a mid production filter improvement, as most of mine don’t make the same noise… the pictures included here, are on a newly purchased unit???
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