[jbrianchamberlin]

How necessary are they? I only ask because I came back from my LFS and they have two of the most beautifully planted aquariums I've ever seen. Both are 75 gal (like mine) and they have two power heads in each. I'm currently using an Eheim canister filter and the output just breaks the surface. I thought this was enough for water movement but now I'm wondering. I also run a bubble wall along the back. Now I'm debating on what a power head would do for me as well.

 

[little dutch]

Powerhead use for freshwater really depends on what you have in the tank. Some fish will not do well with the extra current, some will.

A good use would be to move water into areas that get stagnant because of lots of plants or decor. This is one of their benefits in saltwater, all that rock tends to leave "dead areas" that eventually really do die because the water doesn't get moved.

What is in your tank, or what are you planning for your tank?

 

[jbrianchamberlin]

It's a 75 gal tank... plants..tetras.. couple of angels. I don't really have any dead areas. The water seems to be flowing pretty well just from the out flow of the canister filter.

 

[little dutch]

Don't a lot of tetra's like to nip at the fins of their tank mates? Serpae in particular I think I am thinking of. Had any trouble with that on your angels?

As for the powerhead, I really wouldn't worry about it with that setup. Plenty of 02, not using an under gravel filter, not a crowded plant tank. You will want to double check all of this, but I don't think the tetras and angels really care for the extra water movement either.

EDIT: When I had my 75 set up for freshwater, I was worried about water movement as well. I ended up running 2 smaller HOB filters instead of 1 big one, I felt that did pretty well keeping things circulating. Also, A smaller powerhead rippling the surface might be a good option if you want to try that out instead of just abandoning the idea. Someone else may know more about how much movement those fish are comfortable with.

 

[Dmaaaaax]

I use 2 large canister filters on my 75g: Rena XP4 and a Fluval 305. On top of those, I have 3 small powerheads (one with UV) to help circulate the water at various levels. I try to move at least 10x the size of my tank in terms of GPH.

This is important if you are using CO2 and dosing with nutrients, so that you can get the CO2 and nutrients to all the plants along with O2. You don't need a lot of strong movement so spraybars help diffuse the movement on large canisters.