i've got a cpr cs-100 overflow box that hangs on the back of my 75 gal tank. it's about a year old. i use an aqualifter pump to maintain the siphon on the overflow box, as recommended by the manufacturer. in the last few days, i've noticed that i'm losing siphon on my overflow box (it's not draining as quickly as it should, and if i suck on the siphon tube that the aqualifter sucks on, it starts draining fast again, but a few hours later it's slowed back down, manifested as a rise in my DT water level) i cleaned my aqualifter tonight by flushing the tubes, cleaning the intake piece on the cpr box, and flushing vinegar thru the aqualifter line. it seems to be working better now. i'm wondering if anybody else has had a problem with this type of overflow box - does it ever start to lose air from a bad seal? should i be planning on coating this thing with silicon or replacing it? i'm hoping that my aqualifter is getting old, but i'm afraid that this is a bigger problem. thanks!!