Under Gravel Filter

[OhMyFish]

I'm running an under gravel filter in a 29 gallon tank. (For those interested in the background of the tank, there's a long history at http/www.fishforums.net/index.php?showtopic=255314 ).

I would appreciate it if any one who has personal experience with an under gravel filter would tell me how to maintain it. What should I be doing/not doing? Should I vacuum the gravel? Should I remove some of the gravel and try to vacuum underneathe it? Should I be seeing black or brown material? If so, what size and where (on top of the gravel? under the gravel?)?

Thanks for any and all help!

 

[Schmill]

I used to run an under-gravel filter in my 60L tank many years ago.
My memories of it were a look of filthy gravel through the glass at the front, (in the 'depth' of the gravel, not the surface of it), regularly having to use a gravel vacuum to clean it all, and bad water quality.
Looking back at it now I beleive the bad water quality came from the fact that some of the 'filth' actually made it through the entire gravel layer, AND the plastic tray that the gravel sat on, and would then just sit there at the very bottom of the tank, completely unaccessible without stripping the tank down.
Now maybe I just had a rubbish under-gravel filter, it was one where you have a riser tower in one corner that you shove an airstone into, and that's supposed to make the water flow down throught the gravel and tray, then up the riser.

Whatever the reason for it, my memories of it were bad, the only good think about it was that it was discrete. However when I resurected my tank from the loft earlier this year, (after being away from the hobby for about 10yrs!), the plastic tray was brittle, and the plastic of the riser tower horribly discoloured.
So I opted for an in-tank filte, and what a change
A 'proper' area for course filtration, fine filtration, chemical filtration (activated carbon), and bio-area, and all in a nice tidy unit sat discretely in one corner of the tank. When I need to clean the filter, I take off the top, (complete with bio-media), lift out the sponge carrier, clean the sponges and put it back together. Nice and easy. I still hoover the gravel when I do my water changes, but it's no longer anywhere near as bad as it was with the undergravel filter, and I feel I'm now getting a better 'filtering' too

If you want to stick with the undergravel filter all I can suggest is weekly gravel hoovering, and make sure you give the hoover a good deep root-around in the gravel to get all the much out before it gets through the plastic tray.

 

[waterdrop]

I hope Colin_T (my best guess of who had some very specific advice once..) or oldman47 or one of the old hardware pros who have really had success maintaining a well-functioning UG will please answer!!

Just to start things off I will say what I've read.

[My own background is that I have indeed had undergravel filter setups in my aquariums years ago and so I remember physically how they operate and how they tend to get lots of very liquid black gunk -under- the grid if you -don't- maintain them. And I recall having more of my gravel, which was natural colored, turn very black, which I didn't know at the time but which I now assume was the good nitrifying bacteria stuck to it. And I remember my UG tanks having much dirtier gravel much faster, which doesn't surprise me. But the caveat is that back in those days I also knew nothing special about maintaining a UG and I didn't even fully understand the nitrogen cycle.]

1) The one thing I've read on TFF and that I suspect might be the very best piece of advice was this: Somebody (Colin_T I think?? Sorry if it was someone else?) said that during the weekly gravel clean, one should remove the wide gravel-clean cylinder from one's siphon and, just using the skinny siphon hose part (or having a whole separate siphon hose for this) suck out all the gunk from underneath the slotted undergravel grid plates. The tank gravel above the grid plate needs to be temporarily moved aside for this. The grid itself stays put on the bottom, mostly under gravel, its just that you need to clear "holes" in the gravel here and there so that the little (half inch or whatever it is - its the type clear hose you use for external cannister filters and siphons, easily found in LFS) tube end can be put hard up agains the grid slots and will suck out the black/brown gunk.

2) The gravel in any tank using an undergravel filter needs to potentially be cleaned even more often than a normal tank as it will have a much greater tendency to overload with debris, which will then collect nitrate and ammonia in amounts greater than the bacteria on the gravel can handle.

3) Its important to understand what the ideal UG is meant to be: The beneficial bacteria looking like a black stain is meant to be clinging tightly to the bottom gravel itself, thus turning the gravel into the biological filter as well as the mechanical filter. The corner water pumps or bubblers are pulling water through the gravel and up and out the corners back into the tank. This provides the flow of ammonia and oxygen to the bacteria on the gravel. If the gravel or underpart is too clogged then the bacteria won't get enough oxygen and anaerobic types of bacteria will out-compete it for the positions on the gravel surfaces. The gravel itself and the undergrid part is meant to be as clean as possible to maximize flow and minimize bad pockets of non-moving nitrate and ammonia.

Hopefully OM, MW, Colin_T et. al. will come along and confirm/correct/supplement my description -- Let's hear from you TFF!
~~waterdrop~~

 

[Honeythorn]

Can I ask... would adding ceramic media underneath the Plate on the bottom be a good idea? Seeing as ceramics give a good surface area for bacteria ect, and are hollow/tubes so water can flow through easily? I have a spare 5 gal that came with a basic UG and I was pondering as to wether to keep it or not.

 

[waterdrop]

Can I ask... would adding ceramic media underneath the Plate on the bottom be a good idea? Seeing as ceramics give a good surface area for bacteria ect, and are hollow/tubes so water can flow through easily? I have a spare 5 gal that came with a basic UG and I was pondering as to wether to keep it or not.

That's a really interesting idea Honeythorn! I have no idea - could see the argument going either way. On the one hand, it may be that you desparately need no obstructions under the grid in order to be able to suction out the muck successfully. On the other hand I see your point about how ceramic rings don't obstruct the water very much, compared to other media. It could be that some ceramic rings would be too tall to fit under a typical grid.

It might be worth a try. In your case the UG for a 5g should be so small that frequent cleaning may not be such a burden. I have a feeling frequent and thorough cleaning is pretty important for a UG.

Would be interested to hear how much time it takes you to cycle the thing. Its important to be forwarned it may take longer than a normal filter. In fact, I'm inclined to agree with Schmill that my memories of the things are just awful and virtually every one of the few UG cases we've been helping with here lately have had a very hard time - I just think its not as good technology as the modern internals, HOBs and certainly cannisters. (This however, doesn't change the fact that your UG on a small one may work out ok and has some advantages of not taking up too much room down at that size.)

~~waterdrop~~

 

[OldMan47]

The gravel that you use with a UGF provides plenty of surface area for biological filtration. In my own opinion, I find a UGF irritating in several ways. The filter bed, that's the gravel, needs to be a fairly uniform depth for it to work properly, the gravel depth specified by the manufacturer is fairly critical to proper filtration. Too much gravel means low water flows and a tendency to get some bypass paths through the gravel established, too little and you don't get much filtration. Real plants means that the gravel bed is again not uniform so you get funny flow patterns. Deep vacuuming is a must to keep things clean and I have never been satisfied with how the gravel looks after the first few months. I believe Colin T uses a RUGF which is a different situation entirely. I gave up on UGFs before RUGF became popular so I have never tried that arrangement but the basic idea makes sense to me because it eliminates that area full of fish wastes that you just can never get clean on a UGF.

 

[Honeythorn]

An Rugf? What does the R stand for?

Also, I use ceramic rings in my Eheim 2215 Waterdrop., and that has been running for over 2 years no trouble, so I would simply take some from there ( literally about an handful and a half if that ) and clone it. I do agree wholeheartedly with fishless cycling but IMO it's a right faff and if I can clone a filter I will as it is far quicker and simpler.

By lying the rings on their sides to allow the water through easily, and not totally packing the area under the plate to allow good flow, I think It could work. I thought I'd ask other's opinions anyway though as I've never run a UG before.

I won't be setting the tank up for quite some time, as mother say's no ( I WILL persuade her or wait until I move out ) and I am also going to be doing a steampunk casemod on the exterior of the tank to make it look like a big victorian science experiment, so that will take over a year I estimate ( Copper piping for the exterior and a small sealable bell jar must be found amongst other things ) . So no rush

 

[rabbut]

The caramic rins under the plate should work, just so long as they fit in the space under the plate. The bacteria can transfer from the ceramics to the gravel. I should point out though, that there will be a lot of by-pass arround the ceramics, so only their surfaces at best will remain biologically active. They will only act as a seed.

UGF can be made to work, and look good while working. The issue is that they are realy high maintanance to run well. My LFS has a 140 tank system, all on UGF, that during Uni holidays I maintain. You need to deap clean at least 1/2 the plate each fortnight to keep it ticking over. It isn't advisable to clean the whole lot in one, for the same reason it isn't advisable for normal filters 1/2 at a time, idealy arround once a week would be best. My POW can only usualy manage once every month to two months, and they still look OK when they are comming up to beeing cleaned, but the flow realy has dropped by the time they get done.

Larger gravel works better than fine IMO. It won't clogg the gravel cleaner as often (A real issue while cleaning a UGF) and won't clogg blocking flow as quick.

All the best
Rabbut

 

[waterdrop]

Well, some really good comments there. So, OM47, any idea if it was you I was remembering saying to put the hose right on the grid and suck out all the gunk? Oh, and I too will be interested to hear what the "R" stands for.

~~waterdrop~~

 

[OhMyFish]

Thanks to everyone who has provided opinions, thoughts and shared their past and recent experiences.

When I look under the tank, I can see all the brown stuff that has accumulated under the filter. Ugh. I can't imagine getting any of that out. I did vacuum the gravel this evening and stirred it up a bit but never got to the bottom. There is so much debris floating now, even after a 50% water change.

If the remaining fish die, I know I'll remove everything, clean it as well as I can and begin again with another type of filter. Something tells me, though, that these fish will live and I'll be dealing with the work of this UGF for a very long time to come.

 

[waterdrop]

Interesting that you can see under the bottom of a 29G, must be on a glass topped table or something!

In my experience, the debris accumulation underneath the plates of a UGF will easily suspend in water and should come out if the siphon has enough suction (therein lies the question.) I have heard of people devising simple "water movers" out of aquarium tubing and powerheads, usually to pump large trash cans of conditioned return water back into the aquarium after a water change. I could see one doing the reverse of this in some manner to create more suction than a simple gravity siphon in order to have more pull at the UG plate. (a few more paragraphs of this and one could fall in love with a cannister filter, whatever the cost!)

Did you catch the bit about proper gravel depth? That was a shocker from OM47. I don't remember there ever being any instructions or guidelines that came with those old UGF units that the LFS would throw in as part of a tank set. Sort of upsetting to hear him say that too much gravel depth and the water flow might manage to bypass the gravel, while what little water went through the gravel might move too slowly. That could mean it would be difficult to cycle the gravel.

~~waterdrop~~
ps. HoneyThorn, I figured out that the "R" means "Reverse"

 

[Miss Wiggle]

well there's nothing to say you're stuck with the UGF if the fish live OMF. You could get another filter and run it in tandem with the UGF for a month, the bacteria would move across and clone the filter and then after a month you'd remove all the fish from the tank, remove the UGF, 100% water change and clean out the bottom of the tank properly, put new substrate in, get the other filter going again and pop the fish back in. Bit of prep work and you could have it done in 2/3 hrs so it's not an enormous horrifying prospect to get it changed and not interupt the cycle.

 

[OhMyFish]

well there's nothing to say you're stuck with the UGF if the fish live OMF. You could get another filter and run it in tandem with the UGF for a month, the bacteria would move across and clone the filter and then after a month you'd remove all the fish from the tank, remove the UGF, 100% water change and clean out the bottom of the tank properly, put new substrate in, get the other filter going again and pop the fish back in. Bit of prep work and you could have it done in 2/3 hrs so it's not an enormous horrifying prospect to get it changed and not interupt the cycle.

Ah...Miss Wiggle, you give me hope! Thank you!

The cabinet the tank sits on has an open-style top. Thus, using a flashlight, I can see the bottom of the tank.

There were no instructions as to the dept of the gravel so we put in what appeared to be sufficient to cover the bottom, hold a plant or two, and look nice. That amounted to one medium bag...I think it was 25 lb. Adding the crushed coral hasn't changed it much. I'm ever hopeful that if I stir up the gravel a bit every time I vacuum it, something good is happening. If I'm not careful, the simple gravity siphon I use will take up too much crushed coral and some of the gravel. I do think a stronger one would just empty out the tank of not only the debris but the gravel, too!

 

[Miss Wiggle]

I'm not waterdrop never mind though!

I would suggest as you don't know what depth of gravel you need to make the UG filter function correctly it doesn't take a great leap of faith to say that you may have got it wrong nad inhibited bacteria growth by using too much or too little, this could explain why the tank is taking so long to cycle and get sorted. Can't remember if you've discussed this before, is there any possibility of getting a different filter to run alongside the UGF anytime soon?

 

[OhMyFish]

I'm not waterdrop never mind though!

I would suggest as you don't know what depth of gravel you need to make the UG filter function correctly it doesn't take a great leap of faith to say that you may have got it wrong nad inhibited bacteria growth by using too much or too little, this could explain why the tank is taking so long to cycle and get sorted. Can't remember if you've discussed this before, is there any possibility of getting a different filter to run alongside the UGF anytime soon?

My apologies, Miss Wiggle--post corrected! (Must be on my 4th cup of coffee this morning--not helping at all!)

The full discussion of this tank can be found at http/www.fishforums.net/index.php?showtopic=255314. Basically, my DH insists that an UGF is all that is needed not only because of how one is suppose to work but also because "that's all I ever had as a kid and it was fine." (I do think I need to speak with my FIL and get the "true" story.) I did purchase an in-tank filter but returned it as it would take up way too much space in the tank. Thus, until you gave me hope, I knew I would not be able to change the filtering system until the fish died as another problem is there is no room to hang the filter on the back of the tank (I set the tank too close to the wall so it wouldn't be hit walking by). I have to move the tank which when full, can't be done. Now, all I have to do is find an outside filter on sale. This may take some time (soon never seems to be in my vocabulary) but I will continue to keep an eye out for a reasonable price and move forward to an easier life with this tank. I can then, temporarily hang the filter on one side of the tank and follow your suggestion.