Flow rates for filter media

[redracer77]

What is the best flow rate for different types of filter media?

I have been looking at different filter media and wondering if it is beneficial to have less flow for the Bio? eg;Noodles. Is having the water in contact with this area of the filter for longer going to let the bacteria work better?

I have read that Poret Foam is best with less flow, is this correct?

With my current plans for my sump the water would be passing through quite fast, would slower water movement ie: wider shorter sump be better than long and narrow for the same volume?

[henward]

Flow rate is an interesting thing, but as a general rule of thumb, you can work it out however you want in terms of sump flow capability and stuff.

the more media you have, the less flow you can have, the less media you have, bio media, the more flow you must have.

but th emore flow you have, the better mechanical filtration you will get.

so you can work out your own balance that way.

[David R]

the more media you have, the less flow you can have, the less media you have, bio media, the more flow you must have.

I don't think that's quite right, having more flow won't make up for having less media, you still need adequate contact time for the bacteria to do its thing. How long that contact is I'm not sure, if you think of bioballs in a trickle tower the water isn't in contact with the media for very long at all. You may need more turn-over through the tank with less filter media, but that isn;t the same as having fast flow over the filter media.

If you have too small a sump (or the wrong shape) the water may be moving through there quicker than is ideal, but I think it would have to be pretty fast before you start losing efficiency.

[henward]

I suppose that'sfair. My concept was quite general. But uunderstani ng ow the bio filterworks is the key..

I always prefer a vast amount of media.

[David R]

You're right it is certainly better to have too much rather than not enough, even though the bacteria colony will only grow based on the ammonia produced and not the amount of media available. I've seen calculations somewhere for K1 based on aquaculture practices, using the amount of food fed to work out how much media you need for X amount of fish. Not sure how they relate to other medias though.

[redracer77]

So long contact time with bio, what about mechanical? Is it affected by flow rate?

Can too much flow push particals through where less flow would catch them?

[Ira]

what about mechanical? Is it affected by flow rate?

Can too much flow push particals through where less flow would catch them?

Not unless you go to ridiculous levels. Where you're blowing your filtration sponges apart, tearing bits of debris apart into smaller particles, etc.

[hovmoller]

As a reference you could calculate the flow/cm2 in a large Eheim canister filter and aim for a similar flow rate for your sump. If you do that I'm sure it can't be too wrong.

[David R]

So long contact time with bio, what about mechanical? Is it affected by flow rate?

Can too much flow push particals through where less flow would catch them?

Yes it can, depending on the type of media and how it is set up. A sump with a spray bar dropping water onto wool or sponge will easily have particles forced thru the media. Submerged media with the flow spread out like sponge in a canister (or my sump) isn't as prone to it, same with filter socks IME.