What ever happened UG filters?

Discussion in 'Protein Skimmers, Mechanical Filtration' started by Paul B, 13 Feb 2013.

  1. Paul B

    Paul B

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    What happened to under gravel filters?
    Tropical fish keeping in the US anyway started just after WW2 as people were coming back into civilian life and started looking for a hobby.
    Freshwater fish were cheap and available as "toy" fish and sold in toy stores.
    The filtration on those early tanks were normally an air powered hang on back filter or an in tank, air powered box filter filled with fiberglass floss (nasty stuff). The bottom of the tank used gravel, sometimes colored gravel and under that was an under gravel filter.
    The purpose of the UG filter was to remove particles from the water and augment the fiberglass floss in the box filters. They worked well and we were happy with our fresh water tanks and they gradually became more technical and the fish varieties grew.

    Then in 1971 saltwater fish were imported into the US and many people, myself included just couldn't resist setting up a salt tank.
    We already had fresh water tanks, filters, air pumps and the old stand by, an undegravel filter.
    If it worked in fresh water it should also work in saltwater, right?
    So we set up our salt water tank by first installing an under gravel filter, then adding crushed coral or dolomite. The UG filter was operated with an airstone that pulled water up through the tubes there by forcing water to go through the gravel.
    The device operated as a mechanical filter and trapped all the nasty things that we didn't want in our tank. We never realized that after you trap all that stuff, it stays there and rots. We didn't realize that it is the bacteria that is supposed to eliminate the wastes and not the gravel.
    Our tanks ran well for about a year, then something happened that we could not understand. They were crashing, the fish were full of disease and in some cases the water stunk. When we stirred the gravel, it really stunk which forced us to remove everything from the tank, clean it, change the water and buy new fish.
    Then in the late 70s and 80s other systems started to become common such as wet drys, Jaubert, bare bottom etc. and UG filters were removed and thrown out with the garbage never to be seen again.
    In my opinion, that was a mistake and I still use mine. The problem was not the under gravel filter, but the way we used it. The device was designed to work a specific way in freshwater and needed to be modified to run in a salt tank.
    The modification is simple, it just involves running it in reverse and slowing it down a bit.
    We also need to filter or at least strain the water entering it. Most UG filters use two, three or four uplift tubes and it is complicated to pump water down all those tubes so I remidied that problem by piping all the tubes together in a single manifold where water is pumped into after having gone through a sponge filter. This sponge removes any larger pieces of detritus or food that would get pumped under the gravel. Of course this will not remove all the particles but will greatly help with the maintenance of the device.
    This system actually needs some detritus to run correctly and will not work until some time has passed. Bacteria needs time to colonize the surfaces of the gravel and the detritus that will eventually form between the grains of gravel will slow down the flow of water creating places where anerobic bacteria will grow.
    It will never achieve the nitrate reducing capabilities of a DSB but the fact that it can be maintained insures that it can last forever. The only maintenance needed is to occasionally rinse the sponge filter and once or twice a year stir up the gravel where you can, with a canister filter.
    Noting will run forever without maintenance and I feel that this hour or two of maintenance a year is not that overwhelming.
    The system is also very forgiving and in the 42 years that mine has been operating my power has gone out quite a few times, sometimes for days and there has never been a problem. I once had a very large carpet anemone die and decompose sending pieces of rotting anemone all over the tank, but nothing happened.
    I used to have an urchin collection business and one time I had to many urchins so I put 24 of them in my reef where they all spawned at the same time. The water looked like Half and Half, the five gallon bucket I have under my skimmer that collects the effluent overflowed and I guess about 8 gallons of water was removed from the tank,
    and still, after I cleared the water with a diatom filter, nothing happened.
    The tank houses SPS and LPS corals along with three pairs of spawning fish one of which is a 19 year old fireclown.
    The tank has never crashed and has never been emptied except once in 1979 when I moved to a new house and transfered everything into the tank in my new home.
    The key is to run the device slowly. The slower it is run, the less detritus will be trapped and the longer it will run without maintenance. My tank is 100 gallons and I pump about 500 GPH into the manifold where it equally seperates the water to flow down each tube and under the gravel.
    I am certainly not trying to convince anyone to use an UG filter. My purpose is just to educate about a device that used to be the backbone of the hobby.
    I use this old green HOB filter container as my manifold where the 3 tubes come out of the bottom and travel to the UG filter plates under the gravel. Water is pumped into the manifold through that tube on the left.
    [​IMG]
     
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  3. dallasg

    dallasg Moderator MASA Contributor

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    great post, i posted the same about a reverse UG filter a couple of days ago where i wanted to use one, and many didnt see the value in it, just because some is replaced by some new idea doesnt make it not work anymore
     
  4. leslie hempel

    leslie hempel Moderator MASA Contributor

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    I think UG filters have their place in the marine hobby and even in aquaculture facilities where cost is a factor and people are willing to put a little more effort into their systems from a hands on approach point of view,

    but, (and prove me wrong)

    i dont personally believe they have a place in the modern day reef aquarium at this stage.

    there is nothing that significant about them that cannot be recreated in a smaller more compact form (FBF, Bio Cubes) that warrants their use today, and the fact is that people are lazy and will not maintain the system adequatley giving me the impression i have of it..

    i have seen juvenile holding systems as well as seahorse systems uitilise this filtration system and would say it is probably best suited to these types of tanks..

    believe me, i am not just talking off the bat here.. i come from an era when UGF and RUGF were popular.. i have built and run many systems using it unfortunatley only ever really being stable throughout my school years when it was at its most stable and it does definatley work... i have built many for clients when i worked at the LFS..

    but i still believe we have achieved and simplified (and not simplified enough) the process with LR, to an extent DSB (which i am also not a huge fan of) and refuigiums..

    each filtration method has a place and its up to the person conducting the maintenance to ensure they are well aware of the systems possible shortfalls in order to keep it in peak performance an avoid them...
     
    Last edited: 14 Feb 2013
  5. RiaanP

    RiaanP Moderator

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    Reverse undergravel filter can almost be compared to a very slow fluidised sand bed. Basically that is what happens, water pumped from below. Although not enough to make it fluidized.

    As with other biological filtration systems, all got their pitfalls and maintenance requirements. On a reverse gravel its obvious that sand borrowing fish could open it up and allow water to pass easier at certain spots. Need to keep holes covered. Other than that? If set up correctly I can not think of other issues.

    Anyway, any extra biological filtration is good on any system. Does not matter, as long as it does do something.

    The problem with biological filtrations systems are that we as humans are far to impatient to allow it to mature. How many 2 month old systems are there overstocked? Plus the maintenance needed to keep it in working order. Again we as humans are lazy. Things we do happily as newbie will be a schlep months later. So whatever method we use, it have to be the least amount of work in the long run.

    In your case, the filter option lasted 42 years (that is a long run). Tell this to the guys ripping out filtration options to go to the latest and fashionable options.
     
  6. leslie hempel

    leslie hempel Moderator MASA Contributor

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    I think its important to firstly construct it properly ensuing adequate and even flow through all areas of the substrate,, im definatley more pro RFUG than UGF if i had a gun put to my head :tt2:. but it simply isnt necessary to have either.

    It would be interesting to see at what point and if we ever over filter our system?? everything converts something to something? and this will contribute to the need for a skimmer.. look at why trickle filters were ommited (seen as nitrate factories) but arent we doing the same thing with carbon sorce dosing? just more controlled?
     
  7. dallasg

    dallasg Moderator MASA Contributor

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    i agree leslie, trickle filters like all need to be cleaned, else everything becomes a nitrates factory.
     
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