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I have two of them for my tank , and my father just gave me another , so im wondering if i should use it, ive already tested it and my turtles fine against the current and such , while it makes alot of noise i think its worth keeping the tank clean. so can i ?

Yea it's fine. As long as your turtles aren't being thrown around the tank. A current and breaking the waters surface are both good.

ok awesome ,

They are decent (free is awesome), but might have difficulty priming in lower water levels (after power outages).

More important is to test the ammonia and nitrite levels in the tank. Clear water is not clean water. You won't know if the filters are doing their job without testing your water.

Which brings us to why HOB filters tend to be inadequate for turtle tanks. The ammonia and nitrite are best controlled with bacteria, but typically HOB filters don't have enough media capacity to handle the typical bio-load of a turtle tank. In other words, you can't grow enough bacteria without clogging the filter to deal with the amount of ammonia and nitrates that will be produced by waste and decay.

He's got 3 HOB filters. At some point you can get enough of these to properly filter a turtle tank. I just don't know if 3 is the magic number or if the OP will run out of tank rim parking spots before there's enough HOB running to keep the tank cycled and clean. I'd love to know how big the tank is, how big the turtle is, how many gallons in the tank, and what the nitrite and ammonia readings are.