DIY Multi-Canister Filter

[ruddybop]

I found this link to a canister DIY filter with PVC....Interesting he put the pump in the canister.....

http://www.aquaticplantcentral.com/.../62265-diy-pvc-pipe-canister-filter-step.html

 

[Olly613]

Yeah I've seen that before - I had two concerns mind you. (1) running the power cord out requires either severing it through a small hole, or keeping it intact through a large one. So either I need to trust my electrical skills, or my ability to seal a larger hole (probably the former would be my choice, but still not ideal). (2) larger capacity pumps tend to be physically larger too of course - meaning they become tougher to fit in smaller PVC.

But yeah, that design was somewhat of a springboard for me. But again I want to do several canisters so that it could be in constant operation even while cleaning media. But if an internal pump is desired, a short extra cannister could be attached where my pump shown just as easily.

 

[Chaz88]

Sorry I was making a reply, I didn't see you message there ruddybop.

On that: that a really good point. Hm? Could you link to these vent valves Chaz88? That might be the answer I need. And yeah, based on how soiled each cannister is, they won't necessarily run perfectly even - but they should auto-regulate to some extent shouldn't they? As in, if one fills up really bad, then the other three will start running a bit faster and thus soil at a slightly faster rate. But there's part of the advantage to multiple cannisters right? If one clogs, the whole filtration doesn't fail!

Gonna have to have a think/sleep on that - keep it coming though, this is really helpful (though very distracting from studying for my exam tomorrow, ha!)

I don't have a link. the ones in mine are small nylon finger turn threaded fittings with an O ring. You could use something similar or glue/thread in a small ball valve. Something with an 1/8 to 1/4 inch opening would work fine for bleeding air, you just need to be able to crack it open and close it quickly once the air is out. Random thought... even something like a tire valve stem would work good.
Another thought... if cleaning the media is going to be difficult a few more valves and plumbing would allow you to use the pump to back flush the filters, would cut down on how often you needed to disassemble them and it would not kill the BB.

 

[Dan F]

Oh, and Dan F, just look into the 6" pipes, not only are they expensive (not being all that standard) but they're also tougher to get. So I might revise the dimensions to being 4" pvc with a length more like 2.5-3 foot. Also, 1" pipe does sound more manageable for the other plumbing. Thanks!

Furthermore, the top of each canister may benefit more from using a 4" 45deg 'Y' fitting and a reducer rather than connecting the 1" pipe into the side. Also adding (gluing) some chunk of plastic (or anything) to the cap might remove any space for an air pocket to form. Yay/Nay?

And would there be any merit to me essentially running this in reverse instead? I mean in terms of air build up and what have you?

I know that 6" is ridiculously expensive - just a coupling is $20. 4" won't give you as much volume, but it will be a lot cheaper to play around with.

Also, you're right about reversing the direction - a pump should always push rather than pull. Negative pressure can cause cavitation, which increases noise/wear and decreases flow.

 

[Olly613]

I don't have a link. the ones in mine are small nylon finger turn threaded fittings with an O ring. You could use something similar or glue/thread in a small ball valve. Something with an 1/8 to 1/4 inch opening would work fine for bleeding air, you just need to be able to crack it open and close it quickly once the air is out. Random thought... even something like a tire valve stem would work good.
Another thought... if cleaning the media is going to be difficult a few more valves and plumbing would allow you to use the pump to back flush the filters, would cut down on how often you needed to disassemble them and it would not kill the BB.

Not totally clear on what you mean, but I think I get the gist of how something like that might work. For example, drill a small hole in the cap, silicone a nut on the inside, and with a wing bolt+O ring I could make a cheap air valve. Other idea: Drill a small hole in the cap and run ~1 ft of air line (1/4" i think usually) with a small cheap valve near the end. Then use that to siphon out the air (like you sometimes see in DIY overflows) either manually or otherwise.

I know that 6" is ridiculously expensive - just a coupling is $20. 4" won't give you as much volume, but it will be a lot cheaper to play around with.

Also, you're right about reversing the direction - a pump should always push rather than pull. Negative pressure can cause cavitation, which increases noise/wear and decreases flow.

In my reply earlier, I meant that I looked* at 6" pipe, not for you to do so, sorry if you read it that way. But yeah, the 4" will give me closer to 2 gallons per cylinder (at 3ft), which is way less, but still quite good with 4 of them. If need be, it wouldn't be hard to add another 2 or 4 cylinders as necessary down the road. Another thing that drew me to my design - flexibility and easily upgradeable. Besides, I don't expect to have more than 3-5 fish (although large) in there anytime soon.

In terms of reversing though - I was concerned about cavitation too, but I figured if this were on the ground, and the intake was in the tank around the level of the top of the cylinders, the pump wouldn't be working to hard against gravity (in fact gravity would be helping) to pull the the water. But do you really think putting the pump at the bottom with the soiled water passing through it would actually be better? I mean that in the respect that the pump's lifespan may be shortened greatly (or is that much less of a concern with bigger pumps?)

 

[KaiserSousay]

a pump should always push rather than pull

Need to preface that with a "most of the time"
All shallow well pumping systems "pull" water out of the ground, eh.
I`ve done both, pushed and pulled, depending on conditions.
If cavitation is a problem, it is in the design of the system, not the construction of the pump.
Comparing a canister filter to this project just dosen`t fly.
The only thing they have in common is the moving of water.
Looks like a pretty well thought out project.
Good Job.
Agree, the costs of the PVC parts gets crazy when into the large size pipe.
The upside is, if you build it, you`ll have a bullet proof filter system that you would need to go out of your way to break.
Depending on media choices, could do an exceptional job of filtration.

 

[Dan F]

a pump should always push rather than pull

Need to preface that with a "most of the time"
All shallow well pumping systems "pull" water out of the ground, eh.
I`ve done both, pushed and pulled, depending on conditions.
If cavitation is a problem, it is in the design of the system, not the construction of the pump.
Comparing a canister filter to this project just dosen`t fly.
The only thing they have in common is the moving of water.
Looks like a pretty well thought out project.
Good Job.
Agree, the costs of the PVC parts gets crazy when into the large size pipe.
The upside is, if you build it, you`ll have a bullet proof filter system that you would need to go out of your way to break.
Depending on media choices, could do an exceptional job of filtration.

You're right, I should have said "usually" rather than "always".

In a situation where there is no restriction on the inlet side a pump can pull without a problem. It is only when you restrict flow on the inlet side that you start to create a negative pressure. In a situation like this the pump would probably work fine when the filter is new, but as it clogs there will be an increasing amount of restriction.

On a side note, the fact that the filter is below the tank won't make any difference - the fact that the water has to go back up the same distance that it drops balances out the pressure - if that makes sense.

 

[Chaz88]

For the air valve I would just tap threads into the PVC cap for a threaded nylon fitting with O ring. Or drill a hole to glue in a small valve that is compatible with PVC glue.

As for the pump. Mine is upstream from the canisters. So the pump is gravity fed from the tank then it pushed the water through the canisters and back up to the tank. The picks show the flow from input to output and the last one shows the relief valve on top of one canister. This pump was made for this type of application and the manufacturer recommended installing it up line from the filters. It has been running almost continuously for more than ten years.

 

[Olly613]

Okay, that helps, thank you kindly! I'm working on a revised plan/blueprint, but 'tis a busy season right now. I'll post likely tomorrow night or fairly soon with something, and I'm trying to make cost sheet while I'm at it. But any further suggestions - I'm all ears.

(ps. nice job on your filter there chaz!)

 

[Chaz88]

Okay, that helps, thank you kindly! I'm working on a revised plan/blueprint, but 'tis a busy season right now. I'll post likely tomorrow night or fairly soon with something, and I'm trying to make cost sheet while I'm at it. But any further suggestions - I'm all ears.

(ps. nice job on your filter there chaz!)

Looking forward to seeing the plan. My canisters are obviously commercial ones that I plumed together, and it is running in series. But the concepts are similar. I have planed to do something similar to your design, on a larger scale, for a 1000+ tank that is on my long term planning list. I will be looking forward to the opportunity to plagiarize your design.