Someone asked me how a Reverse Undergravel Filter works and what is the advantage.

[Paul B]

I may have written that article.

 

[Reefvision]

Paul you rock!! Stay healthy man and I love your tank! THE KISS THEORY!

 

[KrisReef]

I sold a lot of these "Reverse Flow" powerheads when they first hit the market. The theory we were hoisting was that pumping oxygenated water through the gravel prevented it from turning anoxic and crashing your tank. We also told people "Live Rock is BEST stocked at at least 2#/gallon" and I don't know why we said that but it must have been true?

Nothing freshens up the air inside of a fish store like a 500# shipment of freshly harvested liverock wrapped in damp newspapers.

 

[Hot2na]

I don't see much value in RUGF...does not remove nitrates...maybe if the bed was deep 4+" ? and flow was real slow...I use a jaubert style plenum and see no nitrates..the ideal way to run one however , IMO - is not in the tank...remote in another separate tank pumped into the main display .. would suggest some kind of fine mechanical filtration to keep dirt low...nothing is perfect ..using a combo with an algae scrubber (as Paul does) helps ...

 

[Paul B]

I'm pretty sure my RUGF doesn't remove much nitrates and that was not my reason for installing the thing. In the early 70s when I started the tank we didn't even know about nitrates as we only kept fish and some inverts. Corals were not available then.

(I use an algae scrubber now with the RUGF but would never run a tank without a RUGF)

I think the main advantage is the fact that oxygen is circulated through the entire substrate so life can exist in much greater numbers there and the gravel will not become anoxic or allow hydrogen sulfide to accumulate like it can in a DSB.

That life under the gravel is mostly microscopic and it supports the multitude of pods and worms I feel are needed for a natural, healthy tank.

The thousands of tiny, red tube worms all through my gravel I feel are advantageous for water conditions but I can't usually read their thoughts through the glass so I am guessing but I also feel if the thing has worked for 51 years with no problems or diseases, how bad could it be?

 

[CoralB]

Back in the day instead of the UG plates we used a pvc grid that we made which was configured to put multiple rows of pvc across the bottom of the tank . We then after glueing it together drilled hundreds of holes in the pvc on the side facing downward then covering the complete set up with pantyhose . We filled it with 3-4 inches of sand . In my tank I used two pvc down tubes using two power heads . The sand would move constantly ,sometime bubbling up it was a neat effect . It would grind up any detritus material . We alway use a hang on the back or canister filter in conjunction as a mechanical filtration some of us would also use carbon . This was basically a fluidized bed sand filter we created in our tanks which morphed into companies making and selling hang on the back fluidized sand bed filter for people to use in bare bottom tanks . At first it was mostly used for freshwater but then carried over to saltwater . Why these filters are not still used in the reef tank industry more today is a mystery . It kind of went away like the wet dry filters .some of your largest fish farms in south Florida I believe still use a extremely large version of fluidized sand filters in the filter systems today

 

[HBtank]

I'm pretty sure my RUGF doesn't remove much nitrates and that was not my reason for installing the thing. In the early 70s when I started the tank we didn't even know about nitrates as we only kept fish and some inverts. Corals were not available then.

(I use an algae scrubber now with the RUGF but would never run a tank without a RUGF)

I think the main advantage is the fact that oxygen is circulated through the entire substrate so life can exist in much greater numbers there and the gravel will not become anoxic or allow hydrogen sulfide to accumulate like it can in a DSB.

That life under the gravel is mostly microscopic and it supports the multitude of pods and worms I feel are needed for a natural, healthy tank.

The thousands of tiny, red tube worms all through my gravel I feel are advantageous for water conditions but I can't usually read their thoughts through the glass so I am guessing but I also feel if the thing has worked for 51 years with no problems or diseases, how bad could it be?

I love that your tank is a constant counterpoint to the “clean” and sterile systems that many strive for. It was one of the reasons I never worried much about that in my system when I started back on RC and saw your tank, which is about 15 years old now. At the time ultra clean SPS systems were becoming the rage. It seems that in the meantime it has swung back the other way with all the BB and dry rock tank failures. I too am never bothered by the constant snow in my tank from sand/detritus.

I occasionally clean my return pump area, but beyond that I let everything be. No RUGF, but I have about 30 pounds of 15 year old rubble jammed in my sump in cryptic refugiums; all that food that goes into the overflow ends up there. Same idea, just a place for anything and everything to colonize, and not compete with autotrophs. Sand is Home Depot silica sand that was recommended at the time, but it has never seemed to cause issues (seems like no one uses it anymore) and I like to think it is part of my ridiculous sponge growth

Anyway, I read about “old tank syndrome” and it feels like it’s those tanks that try to straddle the middle ground, being somewhat diverse but also “clean”. They make it some number of years but just don’t have enough diversity to sustain. My issue is there is just too many reducers and competition for nutrients, it’s basically impossible for me to get residual nitrates to register on my system. Not a terrible problem to have (especially for my fish) as I just feed and dose aminos constantly, since it can take all I can give.

 

[Hot2na]

I think the main advantage is the fact that oxygen is circulated through the entire substrate

just curious : why do you think that would be any different with regular flow ugf ?

 

[Paul B]

I am not quite sure but when the salt hobby started I ran the thing like a regular UG filter and in a few months it crashed and I had to remove the filter and clean the gravel. That happened a couple of times and I couldn't get it to last more than a few months or a year.

Of course it could have just been my inexperience or a number of things I did for my tank because there was no information then so I didn't know what I was doing but I was in the mindset that a UG filter was needed so I just reversed it. I may have invented the concept I really don't know.

But the longest it ran in one place was 40 years. I never had a problem and still don't. As you probably know I don't have any disease problems and never medicate or quarantine but I doubt the UG filter has anything to do with that.

I will never change this system as it seems the most stable and probably the cheapest to.

You can see my gravel in here.

 

[SteveMM62Reef]

For my Deep Sand-bed cleaning I use Nassarius Snails, have Four in my 65 Gallon. Also I use a mixed media bed, from a Course Aragonite to Sugar sand, and Shell rubble,

 

[Eagle_Steve]

I am not quite sure but when the salt hobby started I ran the thing like a regular UG filter and in a few months it crashed and I had to remove the filter and clean the gravel. That happened a couple of times and I couldn't get it to last more than a few months or a year.

Of course it could have just been my inexperience or a number of things I did for my tank because there was no information then so I didn't know what I was doing but I was in the mindset that a UG filter was needed so I just reversed it. I may have invented the concept I really don't know.

But the longest it ran in one place was 40 years. I never had a problem and still don't. As you probably know I don't have any disease problems and never medicate or quarantine but I doubt the UG filter has anything to do with that.

I will never change this system as it seems the most stable and probably the cheapest to.

You can see my gravel in here.

Just to add to this, as this is my thoughts. Paul, you can beat me if you want.

I believe that your tank does not have the typical disease issues for a few reasons.

- You feed well and the tank itself provides an ample supply of healty food. This equates to healthy strong fish.
- You have so many things in the tank critter wise that consumes items the same size as ich trophents. Maybe this is not right that they eat them, but it makes sense that they would. If not then our oceans would be full of ich, right? Something has to eat it somewhere along the line.

As for RUGF, if it works it works. Keep doing what you are doing sir.

 

[Paul B]

Steve one of my things is a lot of biodiversity. That is one of the keys that many people ignore

 

[Eagle_Steve]

Steve one of my things is a lot of biodiversity. That is one of the keys that many people ignore

I agree. While I do QT my fish, ( I just use TTM) the biggest thing I go for is diversity. I have a normal setup in terms of tanks. Some sand, no RUGF, etc, but I keep a massive fuge (my sump was built around being a fuge, not equipment) and prefer to have cryptic areas for sponges and the sorts. I also do not mind some algae in the DT. Never have and will never dose anything to kill it. Chemicals are not the answer. Having such diversity of real ocean rock (some 35 years old and never dry) from all kinds of areas, tons of sponges, pods, worms, and numerous other things is what I contribute to being able to take any rescue nems, coral or whatever and toss it in my tank for it just to heal up and do well. Now dont get me wrong, I do have to treat nems from time to time, but that is due to them being in seriously bad shape. Most nems can just be plopped right in one of my tanks and do just fine. Same with corals from tank breakdown that are not doing well. I think it all has to do with diversity and the things diversity produces.

 

[Hot2na]

eagle steve you can add 1 more ultra important reason : natural sea water

 

[Eagle_Steve]

eagle steve you can add 1 more ultra important reason : natural sea water

That is true, as well. I do not use it right now, but when I was in FL and when I move back, it will be used lol.

 

[C4ctus99]

Little late to this party, but I was thinking about putting a RUGF in my 20g long, but wanted to make certain I had the concept right:
Some sort of distribution system (PVC w/holes, storebought UG filter) with a pan on top with slits in it, then sand/gravel on top of that? So theoretically there is a space between the bottom and the pan where there is only water and it flows up through the pan and substrate?

If I did this, I would also add in a tiny sump/fuge just to experiment and figure out how to set up a much bigger tank in the future. Is it worth putting an RUGF in such a small tank to experiment with and work out kinks?

One last question, do you need any sort of mechanical filtration for the RUGF pump intake or are blockages not generally an issue?

 

[Jekyl]

 

[Jekyl]

With mine I also run a HoB filter and skimmer.

 

[Lasse]

FYI according to a reversed flow undergravel/DSB filter´s capacivity to remove NO3 - please see my thread from here

Build Thread - Lasses Dream Build

Nope - its a traditional Swedish Christmas ham. It is first boiled and then grilled with breadcrumbs in the oven. It is often eaten with mustard on a slice of wort bread. As long as I know we have always make it on the evening before Christmas eve and we always eat it warm on a slice of wort...

www.reef2reef.com

Sincerely Lasse

 

[SteveMM62Reef]

I installed store bought one on my 90 gallon, it covered all of the bottom, except the end that had the internal overflow box. The pumps had Sponge filters over the intakes and the flow could be adjusted. Within Several months I lost all my Copepods and Amphipods. I put one on a 15 gallon with normal flow, that was for Coral and invert quarantine. That Aquarium also had Saltwater Killifish in it as permanent residents. That aquarium kept it’s Copepods and Amphipods.