12-26-2012, 11:34 PM
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Originally Posted by Sanguinefox
It makes no sense design wise to have your water go through the impeller area first and then through your media. Any sand, small bits of plants, or even bits of poop that make it through the intake just end up clogging up the motor/impeller and being a pain.
Well, I won't disagree with the idea that the canister pulling water through the filter first is the better design. I will disagree that it makes no sense to go impeller first on HOB filters... I consider it a necessary evil given the need to fill a low to medium end market need. I'm in that market, I priced canisters.
If the impeller were last, it wouldn't work very well. The weak impeller draw (not a high quality pump mechanism) would fail as the filter got clogged and the circulation of the water would stop. In the HOB filters that I looked at, they have a bypass function so the water will still flow around the filter media when it is clogged. In my case, that is not a problem as the filter is secondary anyway.
If the impeller is anything like the small pond pumps, I really don't see the problem with having to clean it occasionally. Just wrap the intake with a coarse foam filter media to avoid the worst of it and extend the time between cleanings.... or anti up for a canister.