Reverse under gravel filtration

[jaylach]

Anyone ever hear of this or used? Instead of using air lines in the filter's air risers you use a pump to push water down the risers so the flow is from under the gravel to the water column instead of going from the top down. A guy on the Sheridan WY aquatics Society that I frequent here locally swears by this for his shrimp tanks.

I can see where this would prevent sediment from building up under the filter plates but would think that it would just put stuff that settles back to the water column.

 

[FranciscoB]

Very old. Not very effective. Has been around for a long time.

 

[jaylach]

Very old. Not very effective. Has been around for a long time.

Thanks. Since I've running normal under gravel since the early 1980's, and still do, I'm surprised I never heard of it.

 

[StevenF]

Not commonly used but it does work.

 

[jaylach]

Not commonly used but it does work.

Thanks. Still seems to me that it would 'push' crud that settles to the substrate back into the water column.

This system is used in shrimp and scud tanks by a guy on a local aquatics Facebook group. BTW, I suggest that all look for such groups as they can be a great resource. I posted my intent to start breeding fresh water scuds to the group and within a day I was offered a tank by one person and scuds to get started by another. I almost grabbed a tank but put it on hold as all the 5 gallon tanks the lady has are glass. Since the tank (5 gallon) will probably go on my kitchen counter I really want acrylic as there would be the potential of the tank getting some abuse. I'm actually looking for a single piece molded tank with no seems. I'm pretty sure they make the things but I've had no luck yet finding.

 

[TwoTankAmin]

Yes. I started with a normal UGF and then converted to the RUGF. It is still one of the best biological filters there is when done properly. However, it is not suitible for a lot of tanks. It provides a massive place for bacteria to colonize.

However, today, a Hamburg Mattenfilter in a bare bottom tank will work as well and is easier to maintain and takes up less space. Plus you will get denitrification. I use these in a few tanks.

The way ther RUGF works is in concert with a second filter set up to trap mechanical waste. The water is pumped down the uplift tube and it ecits under the plate. Frome there it travels up throught the gravel and into the water column. The intake of the pump send the water down the tube must be sponged to prevent all but the finest debris from going down the tube,.

Because the flow is up through the gravel much of what would normally settle on the surface and then be broken down some and sink, or be sucked. into the gravel is now being kept in the water. This is the rsesult of the rising flow/ So pme needs the second filter to get that stuff out of thw water. A small H.O.B/ filled with media to catch the debris works great. other filters can be used for this as well.

Basically the antire substrate becomes the filter and the water is cleaned/polished by the mechaical filter. I ued the no longer availaable H.O/T/Magnum 250 gph with the micron cartridges. I had this on a 45 ggal tank that was eventually planted. This means no sunsstrate ferts as they just get blown into th water column.

Finally, under gravel filters cannot be used with fish that are serious digger.

 

[jaylach]

Thanks for the inputs. Sounds interesting but not something that I think I would do even though I could on my main tank as it already has normal UG along with a built in sponge filter. It would not take much to direct the output from the sponge to the risers for the UG and seal. Just does not seem worth the bother plus I would loose the surface agitation from the air risers and sponge outlet probably lowering the oxygen level of the water.

I could possibly see such a system for crustaceans but I just don't like the idea for fish. I'm old school and sort of set in my ways. It just does not 'feel' right even though I'm an advocate for normal UG.

 

[TwoTankAmin]

You get that agitation from the added hang-on for the mech filtration the return from which agitates the water.

You also get to vacuum the tank less because the stuff you would vac stays in the water table and goes through the mech filter

The key is to have the proper size gravel and the proper depth.

 

[jaylach]

You get that agitation from the added hang-on for the mech filtration the return from which agitates the water.

You also get to vacuum the tank less because the stuff you would vac stays in the water table and goes through the mech filter

The key is to have the proper size gravel and the proper depth.

That is all well and good but I can't really see any reason to change my current main tank setup and won't have mechanical filter in my 5 gallon scud tank when I get it together.

This thread was not to mean that this was something I was thinking about doing. It was just to gather info to expand my meager knowledge.

 

[Ichthys]

Finally, under gravel filters cannot be used with fish that are serious digger.

Actually they can.

Digging around in the gravel will not dislodge bacteria, just like giving sponges a good squeeze won’t, since the bacteria produce a very strong glue/cement to attach themselves to the surface they’re in contact with.
I’ve known, and kept, even extreme diggers like various large cichlids that will try to hide by piling all the gravel up against the front glass, on many occasions (more commonly the end glass when a tank is end-on). You never get an ammonia reading. UGs even work well when a large majority of the plate is exposed in this way. There is still some flow through the gravel, wherever it is.

When I started keeping fish over 50 years ago UG was all we had. Then ‘power heads’ were invented and reverse flow UG became popular. Then canisters were invented and UGs slowly declined, mainly because they were quieter, less ‘obtrusive’, and easier to clean. Also because they were new. Manufacturers are always inventing new stuff and telling us we need it.

Two pieces of advice from me about UGs…
1. Don’t use a layer of wool between the gravel and the plate. It clogs and slows down the flow, and eventually needs replaced, just like in a canister.
2. Cleaning out the mulm that builds up under the plate is a) not necessary since the mulm is inert and will stay where it is, and b) very easy. Just remove the airline and push a siphon pipe down the uplift right to the bottom. This will pull out all the muck. This works best if the uplifts end below the surface, or if the uplift is in two parts, as in a tall tank, and you can remove the top part, since it will pull water down the other uplift (one at each end?), and you can get all the muck out in one go.

 

[jaylach]

Actually they can. When I started keeping fish over 50 years ago UG was all we had. Then ‘power heads’ were invented and reverse flow UG became popular. Then canisters we’re invented and UGs slowly declined, mainly because they were quieter, less ‘obtrusive’, and easier to clean. Also because they were new. Manufacturers are always inventing new stuff and telling us we need it.
Digging around in the gravel will not dislodge bacteria, just like giving sponges a good squeeze won’t, since the bacteria produce a very strong glue/cement to attach themselves to the surface they’re in contact with.
I’ve known, and kept, even extreme diggers like the various large cichlids that try to hide by piling all the gravel up against the front glass, on many occasions. You never get an ammonia reading. UGs even work well when a large majority of the plate is exposed in this way. There is still some flow through the gravel, wherever it is.

Thank you!

 

[GaryE]

Being very cheap, I used to make my own UG filters. I bought a tank with a DIY set up, liked it and tried it. It took a saw and some plumbing fittings. For a while (and I haven't checked) you could get powerheads that were easy to put in reverse. Then you'd do a water change for the stirred up sediment. I think they even marketed reverse systems.
I bred Satanoperca with a UG, and eartheaters move gravel. They were fine.

We had a warehouse store here in the 90s- one of those 250 freshwater tank places. It was thriving and was bought by a total novice to aquariums - a young guy with deep pockets. He installed UGs in all the tanks, but with no gravel. I can say THAT didn't work. He was very stubborn, and the store no longer exists.

@jaylach keeps making me want to start up another air driven UG. I may make one this summer. It was an excellent technology.

 

[Ichthys]

We had a warehouse store here in the 90s- one of those 250 freshwater tank places. It was thriving and was bought by a total novice to aquariums - a young guy with deep pockets. He installed UGs in all the tanks, but with no gravel. I can say THAT didn't work. He was very stubborn, and the store no longer exists.

We could probably make a thread about this kind of intelligence. Like the guy that said his tank wasn’t heating up despite the fact that the heater element was constantly glowing red hot. He lived on my way home so I went to see. He had the heater/stat stuck on the outside of the glass.