Behind Tank PVC pipe filter

[john73738]

Hey,

Been a long time since I posted here. My 240 (see my signature) is running a bit rough and I need a bunch more filtration. I wont get into why just know it was a total bonehead move. I have an idea for a behind tank filter that if I build a pair should give me a total of 1800 GPH filtration. Should be good.

Pardon my crude drawing but I am not near a decent computer to use Fusion 360.

Here is my thought. Mechanical/Chemical will be 3" PVC pipe. The Bio chambers will be 4" PVC with screw on caps. It will have, but not pictured a spray bar inside to distribute the water between all 3 chambers.

I hope my idea is conveyed and does anyone think this could work?

Thanks

Bear.

 

[kingthedog]

it depends on what mechanical media and how often It is cleaned/replaced because It will eventually get clogged and slow the water flow

 

[esoxlucius]

Where is your pump going to go to send the water back to the tank?

Once this structure is up and running behind a filled tank how are you going to maintain it, seems to me you are going to have real access problems to it.

Only a 3" diameter mechanical chamber? I'd be scared to death the mech side would clog up and what then?

There's certainly easier ways to filter a tank.

 

[kingthedog]

That is a pretty cool idea though

 

[tlindsey]

I agree with the above. Personally would do a large sump with a filter sock or other mechanical material and lots of bio media. Please update if you go ahead with the project.

 

[duanes]

I'd probably us a filter sock in the first chamber, for easy cleaning, but ad an overflow pipe (maybe 0.75 inch or 1") between the first and second chamber to alleviate the problem of overflow as media gets plugged, the eventual problem Exolucius brought up.
I might put a bypass line with a shut off valve to each chamber in case one chamber needed to be shut down, and removed for maintenance, like gunk removal.
And I know its expensive, but I like clear PVC in any application where I want to be able to see whats going on, other than just looking down from the top.

Seems like a reasonable system to me, as long as there is enough room to do maintenance behind the tank

 

[Backfromthedead]

Seems innovative, but perhaps a bit too complex (for me at least). Why all the different chambers though? Is this intended to be a closed, pressurized system?

 

[john73738]

I originally set the tank up with an above tank sump built into a hood. I worked really well until it clogged and overflowed. I then cut my nose off to spite my face and removed it rather than just fixing my design flaw and moving on. Been regretting it ever since. Under tank sump is not possible due to design of stand. Another design flaw.

Thanks for the input, I am going to do some rethinking. My idea here is that when I replace the tank, maybe next year I can move it under the tank as canister filters and a large sump. My new tank is going to be near 500 gallons.

Access for cleaning would be through clean out plugs on the top of each chamber.

Output would be at the return standpipe.

I would use filter socks for the mechanical media. I would also add a way to disconnect and it could be slid out from behind the tank for deep cleaning. I would also add a drain so I could do a backwash of sorts to clean it.

I was really stupid when I removed the above tank sump and replaced it with a single FX4. Tank has looked like crap ever since and now I am fighting a bad nitrate problem and my fish are looking terrible. I temporarily added a pair of large air driven sponge bio filters to help reduce the nitrate problem, doing more frequent cleanings and water changes. Will be adding a half dozen moss balls to assist as well. But I really need to get the filtration problem fixed before I kill my fish.

 

[john73738]

Seems innovative, but perhaps a bit too complex (for me at least). Why all the different chambers though? Is this intended to be a closed, pressurized system?

See above, it will someday be a closed system as a canister filter. The multiple chambers is to get as much bio medial as I possibly can in it.

 

[andyroo]

Hi Jon. I've been thinking along similar lines, of discrete 4" pipe "stacks" as I've got lots of vertical but not much horizontal space, and sealing fittings are an ongoing issue. 4" pipe is common, inexpensive & easy to work with.

Threaded O'ring fitting on the top for access/cleaning
Exit pipe in the last/top inches (at most) of the stack,
Entry pipe ~1/4 of the way up from the bottom of the stack, and a
Smaller pipe with lock-off valve towards/at the bottom.
Pump would likely have to be in the tank or either the in or out lines, unfortunately.
Sealed system, yes.

Fill stack with course media (in my case a 3' quartered bamboo charcoal) to ~75% of height, followed by meshes/foams for water-polish as desired.
Water comes in and majority of the the gunk/flock is caught in the course media, along with BB, ostracods, snails & other biological elements.
Every month, you turn the pump off & knock/shake the stack, let it settle, repeat maybe three times over a David Attenborough special. Turn the bottom lock-off into a potted fern & voila: backwash. By no means perfect, but should reduce cleaning effort by at least half on a sealed/pressurized system.
4" pipe won't let me use a very big pump (if intention is crud collection), thus having a plurality of discrete stacks on smaller Cobalt type drives.
Still very much a thought-experiment, to give it a go in the spring.