I've used Hagen AquaClear Powerheads in freshwater tanks for years. Everything from 201's to 801's. A few of them have burned up but I'd guess it was mainly my fault for not cleaning them often enough or even ever. I'm currently using two 301's and two 801's in a 75 gal
saltwater tank and find that I need to do regular maintance on them to keep good waterflow. Mainly I'm cleaning the intakes of debris and while I have them apart I've been scrubbing the impellers a little. I've never heard of an AquaClear 4000 so I can't give you any input on that particular model.
Hope this helps
AquaC Remora Pro
140#s Live Rock from LiveRocks.com
Frogspawn, Hammer, Zoos, Leather Frag, and Xenia and Green Star Polyp frags from fishfreek and Alarmguy66, Thanks!
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