also tom, i know you have a 25 watt gamma. think of it this way you are running a high volume pump, so the water is gonna be forced through there pretty fast. which does not give the sterilizer adequate time to do it's job properly. on my 8 watt in he closed loop, i have a rio 2100 recirculating through it. so the water is moving through there slower it has more contact time. to work more effectively. give this a thought. you might like the results you get. remember this is just my opinion you can try what you like. hey you know what i'll send you some pics via e-mail so you can see how i set mine up, cool?