Biomedia and water flow- can there be too much?

[Johnez]

I just bought a Lifeguard Quiet One 3000 pump (actually 2 since they were on sale lol) for a DIY canister filter to filter a 75 gallon tank and am of course wondering now if I goofed by going overboard on the GPH. My main concern right now is will the water flow through the canister be too fast for bacteria in the biomedia to do their job? At 4 feet of head should get about 550 GPH. I'm planning on using a 5 gallon bucket on this project.

So my question is should I get smaller pumps and maybe run 2 canisters or should this work out ok? I'm also considering lowering the flow with a ball valve though I'm not sure if this will put too much strain on the pump.

Also, side note-I'm planning on stocking with a shoal of Firemouths, 4 swords, and 6 Cories. I've read I need anywhere between 4-10 times turnover per hour, I figure 7 is a good start point and I can always throw an overhead sump if I need more. I also don't want the flow to be too strong.

Also, before anyone tells me to get a sunsun, I'm fully aware I can get a really cheap filter. I'm dead set on trying this out, mainly because there is no definitive DIY filter champ and I want to see if I can do it. Joey has made 2 cool ones, but I don't like the fact that the gamma lids are hit and miss, and I don't like the screw on tops for the PVC build. For me it's a challenge, and hell if it doesn't work I can always get a few sunsuns.

 

[Johnez]

Well damn I just reread the Firemouths come from slow moving waters. Shoot. Maybe I'll end up doing a sump. Son of a gun. I'm curious still for my bro's tank which I'm still adding a canister for.

 

[heffesuita]

Those pumps should come with flow control on them allready

 

[duanes]

If it doesn't come with a flow control, you can easy adjust flow by getting a PVC ball or gate valve, to throttle it back on the outflow of the pump.

or tee off or create a manifold that makes multiple water entry points into the tank to diffuse flow.

As you can see, I have a couple pointing the length of the tank, and a couple pointed straight down.
Also one thing to consider, is a slow flowing river, is often much stronger than we as aquarists might perceive as slow.
The fish in the tank above, are not considered rheophillic, yet in the river they were caught, a human would easily need use effort to not be swept downstream, while snorkeling, yet for the fish, that flow was effortless to swim against.
You can also tee off and add other forms of filtration (such fluidized beds, UV lines, fractionators, etc) that would lessen the flow directly in or to the tank.
I have used fluidized bed reactors that returned water back to the sump, as opposed to directly to the tank.

As you can see above, there is a strong water flow line to the reactor, that return water to the sump.
And you can see in the tank below, flow is enough to bend plants, but the cichlids (Cribroheros rostratus, very similar earth eating species to FMs)are hardly phased by the water flow.

 

[duanes]

Also consider that some of the best filtration for biomedia, is a fluidized bed, the forces media in motion, where pieces collide.
This excess motion and collisions allow only the most robust biofilm to remain, and sloughs off the older , tired biofilm making the biofilter more efficient.

Consider trout streams, or fast flowing rives where rheophillic cichlids such as Tomocichla live.
These species need highly oxygenated, high water quality, where the beneficial bacteria there, thrive in those fast flow type conditions.
I find many aquarists vastly underestimate the movement of water their fish come from in nature

 

[esoxlucius]

The short answer to your question will be no, the BB will not be effected by a high flow, even excessively high. As long as the water is nutrient and oxygen rich and the PH and temperature are within their desired "operating" levels, and light intensity isn't too high (they prefer the dark), then BB will do just fine.

It'll be your fish (species dependant), plants and decor that suffer from excessively high flow because they'll be blown all over the place!

 

[Johnez]

Those pumps should come with flow control on them allready

Yes, it does have flow control on the outer shell I believe, but I'm going to pipe it directly which I'm assuming will require removal of that.

esoxlucius- thanks, and yes many cichlids require high oxygenated water, tho Firemouths less so.

Duanes- wow you are a wealth of knowledge. I'll take up the idea of a moving reactor. Didn't even consider that! Some great perspective on natural habitats versus aquarist expectations. I suppose the best way forward is to set it up and see how the fish react and adjust from there. Another thing that came to mind is there are layers of water, similar to the atmosphere, that have different speeds of flow so maybe all will work out. Thanks again for you guys input. Great stuff!