# Canister filter flow direction



## Baggly (Feb 2, 2012)

I am building a canister filter. I am going to be using a floss/bio media combo. My pump will be plumbed to the canister and not inside it. My question is which flow direction would be more beneficial: up through the filter and out the top, or down through the top and out the bottom? I will be pulling the water through the canister so I reduce build up on the pump impeller/housing/tubing. Having the water come in from the top would certainly make changing/cleaning the sponge much easier.


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## 13razorbackfan (Sep 28, 2011)

Personally....I prefer the pump at the top with the water being filtered before reaching the pump. I am not sure how easy that would be to do on a DIY project such as this.


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## Baggly (Feb 2, 2012)

Here is the design. There are a few reasons why I am making my own filter. I have a pump already. I'm cheap, errr frugal, yeh that's it. Most importantly, the goofy stand with this tank has three very narrow cabinet doors. I would not be able to get a large canister to fit. I measured the FX5, Rena's, even the large Eheim will not fit  . I had access to some polypropylene sheets and a thermoplastic welder so I made my own canister. If it proves to be a disaster I guess I'll have to do a sump or use several small filters like and Eheim 2217 (barely fits through the cabinet doors).

The intake from the tank will feed to the top of the canister and be pulled out the bottom and returned to the tank through two spray bars and the UGJs. I'll have ball valves on each of the spray bars and UGJs to control flow. I plan on using filter floss in the top of the canister, followed by some rings and a bunch of pot scrubbers. The canister has a volume of 11 gallons.


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## 13razorbackfan (Sep 28, 2011)

Looks like it would work ok as long as it filters before it reaches the pump which is the case with this design. 11 gallons is pretty good size. What size tank is this going on?

PS...remember in calculating the GPH to account for head loss, etc....


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## Baggly (Feb 2, 2012)

125g. pumps rated at 840 gph at 10' of head. I'm hoping its enough. I have six jets and two spray bars so I'm looking at around 100 gph each. I guess i won't really know until I get this thing put together.


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## 13razorbackfan (Sep 28, 2011)

Baggly said:


> 125g. pumps rated at 840 gph at 10' of head. I'm hoping its enough. I have six jets and two spray bars so I'm looking at around 100 gph each. I guess i won't really know until I get this thing put together.


Hard to say but with the UGJ then you should be ok as far as circulation. How are you planning on building the canister...specifics?


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## Baggly (Feb 2, 2012)

I used 1/2" polypropylene . Cut them to size and welded them together (rectangle). I cut a groove in the top plate for an o-ring and drilled and tapped around the edge using 1/4-20 stainless bolts. I'll post a picture. I ran it for 24 hours under pressure with no leaks!


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## 13razorbackfan (Sep 28, 2011)

Baggly said:


> I used 1/2" polypropylene . Cut them to size and welded them together (rectangle). I cut a groove in the top plate for an o-ring and drilled and tapped around the edge using 1/4-20 stainless bolts. I'll post a picture. I ran it for 24 hours under pressure with no leaks!


Sounds good...make sure to lube the o rings lubed so they keep a good seal.


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## Baggly (Feb 2, 2012)

here is my diy canister


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## 13razorbackfan (Sep 28, 2011)

Where did you get the casing?


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## brinkles (Jan 30, 2011)

He welded it up. Nice CNC work! What type of machine?


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## 13razorbackfan (Sep 28, 2011)

brinkles said:


> He welded it up. Nice CNC work! What type of machine?


Nice indeed. That thing looks bulletproof quite literally.


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## brinkles (Jan 30, 2011)

I've tried my hand at hot air welding - apparently it's an acquired skill!


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## Baggly (Feb 2, 2012)

brinkles said:


> He welded it up. Nice CNC work! What type of machine?


A waterjet to cut the grating and Mitsui Seiki to mill the o-ring slot and drill/tap the holes. I think this is the welder I used, http://seelyeincorl.thomasnet.com/image ... temid=1005 Unfortunately, I don't think it is going to work. I did not take into account the amount of suction that would be placed on the canister. The sides are sucking in quite a bit and it's sucking air somewhere. It doesn't leak water but the pump is cavitating pretty hard. I'm afraid that over time it may crack because of all the flexing. I think I'm going to build a sump now :lol:


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## Deeda (Oct 12, 2012)

Any chance you can increase the size of the fittings?

Your other choice would be to put the pump on the intake side of the canister filter.

I'm curious, what brand/model pump are you using?


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## 123vb123 (Feb 10, 2012)

My uncle did something very similar for his pond, (same idea)

*edit* - and working great by the way


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## brinkles (Jan 30, 2011)

Sounds like way too much pump! Maybe you could throttle it on the return side? Weld a brace into the canister? That thing looks great, don't give up on it!


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## Baggly (Feb 2, 2012)

This is the pump. http://www.grainger.com/Grainger/LITTLE ... Pid=search I can't even remember where it came from but I had it lying around so I thought I'd give it a go. It's returning ~700 gph to the tank after all the hose, pvc and filter so the size I think will work. I was talking with a buddy about installing some braces and it seems like a worthwhile idea. I'm using 3/4" fittings, hose and pvc because that's what I had. Maybe I'll go up to 1" and see if that helps.

I found out my tank is tempered by the way :x so I don't think I'll do a sump.

If I can't get this to work I guess I'll have to break down and spend the dough. It'll have to be either three or four small canisters or build a new stand/canopy so an FX5 will fit, ugh.

Thanks for the replies.


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## brinkles (Jan 30, 2011)

That's a big pump! I'd drastically increase the sizes on the intake side, and leave the return alone. You shouldn't be able to hurt a pump by restricting the outlet. Maybe even double up the inlets at 1" so you don't kill the pump if one of them gets clogged? That thing looks awesome, way better than the commercial stuff.

What's the Mitsui Seiki really for? Does that stuff waterjet nice?


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