Reverse undergravel filtration setup

Oughtsix

Redtail Catfish
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Apr 9, 2011
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30+ years ago when power heads first came out in an affordable form I tried the reverse flow under gravel filter. I honestly did not see any improvement in the tank and most of all the gravel did not stay any cleaner. I did not have a canister at the time (they were expensive and I was young and broke) so I don't know if that will make a difference. At the time I was running HOB filters.

As stated above the biggest improvement to a tank will be to remove the debris from the system. If the debris is in the gravel or in a canister filter it doesn't make much difference as it is still breaking down into nitrogen compounds. As Duanes said cleaning a canister filter (or any mechanical filter) frequently is probably the healthiest thing you can do for your aquarium.

Just my 2 cents. :)
 
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Soni

Feeder Fish
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Thanks everyone for your advise. I have input if my canister filter go in tube if one end of ug filter and on the other end powerhead in reverse.

I do have thin layer of gravel ( not sure if they should be thicker?)

I have seen that there is massive bubbles near the long tube if ug filter so not sure if that is how it should be. However, i do have the venturi working as well.

Am i doing anything wrong?

Appreciate your advise.

Thanks
 

andyroo

Peacock Bass
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Apr 17, 2011
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I'm curious about this - yes, it should greatly increase post-filtration digestion of nitrogenous wastes, both aerobically & anaerobically as you can expect points of compaction &/or eddies where the through-gravel current is less & O2 will be exhausted.

However, those sorts of spots should also accumulate detritus (poop), as per esoxlucius esoxlucius , which may be problematic, so maybe don't rely entirely on the set-up; you'll still have to stir & gravel-vac from time to time. Good thing on this is that the actual space/area of such accumulation will be greatly reduced, and the the rummaging of the (gold)fish help it get too old.

Maybe augment the latter with other fish that dig and/or self-bury properly - an eel (Anguillae) will get this done nicely and be temperature appropriate, as might some of the longer-body, cooler-water loaches such as weather/dojo... though they've also got a habit of getting underneath the sub-gravel tray. Me, I love MTS for this remixing job, along with tubifex(?) and/or related non-drowning annelids. The fish will appreciate such "enrichment", too :)
 
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Soni

Feeder Fish
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Here is video. Not sure was it attached in my previous post.

 

jjohnwm

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I played with the reverse-flow concept a bunch back in the day. The big "selling point" that was being used to market these was the idea that the gravel stayed cleaner; this was true to a certain extent, but only if you make sure that the water being pumped down into the plenum beneath the gravel is clean to begin with. Just sticking an upside-down powerhead on top of the lift tube and forcing water under the plate is no better, or worse, than a standard UG filter. The water needs to be passed through an efficient mechanical filter first, so that there is little or no particulate matter being pumped in.

This was a neat thing to play around with; I had several large tanks, including a 120-gallon marine tank, set up with various DIY contraptions that all achieved the same goal: pumping clean water under the gravel. Yeah...this was so long ago that we were still using UG filters for salt water! :) The easiest way was to make your own filter plate with eggcrate/nylon screening, and then siliconing a partition at one end or one corner of the tank. A big HOB filter was placed on that partitioned area, and the intake was extended using PVC pipe to pick up water from the main tank area. The overflow from the HOB dumped the filtered water behind the partition, at which point it flowed down under the plate and percolated back up into the tank. It worked; the marine tank ran for years that way, and produced armloads of Caulerpa alga to be harvested every week. The partitioned area was also a good place to stick heaters, protein skimmers, etc...it was like having an in-tank sump.

Reverse-flow UG filtration is a neat idea to play with if you enjoy DIY projects. If you like a tank with shiny new-tech whiz-bang filters and other goodies...then it's about the biggest waste of time imaginable. :)
 

Soni

Feeder Fish
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Mar 29, 2020
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Thanks for your response. But am nit sure if you understand that i havr a massive canister that is pumping clean water undergravel. Not if anyone us getting the point that i am trying to identify what am i doing wrong that there are bubbles near the lufttube. I have the venturi activated so is it normal to be like that becayse am pumping more air to my tank? If i take off the venturi i cannot see the bubbles. Any helpful advise will help
 

duanes

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It would be normal with the venturi attached to the powerhead, to send air bubbles down the main tube its pushing flow down, and for the bubbles to then escape up the next nearest opening (the hole where the air tube is normally connected to provide lift) from the UG if used the conventional way.. Air water, will always seek the closest easiest route.
Sending extra air is what ventures do, but unless you intentionally plug the air tube hole on the UG filter plate, that is where it will come out.
I do not understand the confusion, unless your intention ids to have those air bubbles to be escaping up amid the gravel itself.
If so, you will need to dam up the small air line hole, behind the main (larger tube).
 

suckerfish

Dovii
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Nov 8, 2005
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Take the airline out. It seems to me that your just pushing water down from power head straight into the canister, completely bypassing gravel. Hey, some people keep filtration, some keep fish. I think your in the first category.
 
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