Under Gravel Filtration, do they really work?

[rwhitham]

I have a Marineland 12 [acronym:fdaa4f6e30="Gallon"]gal[/acronym:fdaa4f6e30]. Eclipse setup, I'm thinking of putting a under gravel filter system. Is it worth having and what's the benefit.

[nejsux]

[acronym:794c67e46d="In my opinion"]IMO[/acronym:794c67e46d] you'd be better off with something else. Taken from http://www.bestfish.com/ug.html :

"The theory of undergravel (UG) filtration. It is generally acknowledged that there are three forms of filtration: biological, in which ammonia and nitrite of fish waste is broken down by bacteria, chemical, in which carbon or resins are used to adsorb dissolved waste, and mechanical, in which solid waste is strained from the water by floss or filter cartridges. Of these, a UG filter effectively provides only biological filtration. The small amount of charcoal in a UG cartridge does very little chemical filtration before becoming saturated and whatever mechanical filtration occurs is actually a threat to the stability of the aquarium (more about this later). In theory, the UG filter circulates water through the gravel, where healthy bacteria grow and break down the fish waste. Promoters of UG filters often argue that you cannot culture these bacteria without an UG filter, that ammonia and nitrite levels will rise and fish will die.

Our experience has been just the opposite. As you look around at our 200 aquariums, loaded with 5 to 10 times the usual number of fish per gallon, you will find no UG filters in either freshwater or saltwater. And yet, we never find dangerous ammonia or nitrite levels in any of them. It seems that the bacterial culture grows perfectly well on the gravel, the glasses and any other surface in the aquarium that has water circulating around it. We perform hundreds of water quality tests for our customers each month, and the vast majority of ammonia and nitrite problems in established tanks involve UG filters. Declining pH and live plant problems are also much more common in UG filtered tanks. When the culture is dependent on the UG system, an otherwise minor mistake or mechanical failure can cause a die-off of the bacteria and fish loss. When we used UG filters on our saltwater aquariums a few years ago, we often lost an entire tank full of fish overnight when a power head would quit. The power head would stop due to gravel packing, salt spray penetrating the motor or an anemone blocking the intake, and the bacteria (and fish) would be dead before we noticed it. In more recent cases when a power filter would quit, there were no major fish losses unless aeration was also interrupted.

The risks of UG filters. If all else is perfect - if the fish are not overfed, if circulation is not hindered, if the tank is not medicated, and if the gravel is cleaned frequently with water changes - success can be achieved using UG filters. We stock UG filters and power heads mostly for those experienced hobbyists who have had previous success. Unfortunately, in most cases, something is less than perfect. Usually, after a few months of operation, the gravel begins to pack with so much silt and dirt that circulation stops and the bacteria suffocate. Since the filter still appears to be working, water quality deteriorates, usually unnoticed until it is too late. If the tank is medicated or overfed, an even more rapid die-off of the culture may occur. A speedy water change may avert disaster, but this is the sort of headache and frustration we are trying to spare our customers.

The best filtration. We have had excellent success with box filters for smaller aquariums and power filters or canister filters for larger aquariums. They usually cost less than an UG filter with a pump to provide similar output. In addition to providing circulation for our biological filtration, they also are far superior mechanical and chemical filters. And since solid waste is collected in filter fiber or a filter cartridge and is easily disposed of, it is not allowed to accumulate and rot in the aquarium. Tanks stay clearer and odor-free with less maintainence by the hobbyist. And, as we mentioned above, we have found much less risk of problems of ammonia or nitrite poisoning. "

[Biggen]

[acronym:2cff63bca1="Under Gravel Filter"]UGF[/acronym:2cff63bca1] are good filters, but the problem is that they eventually will have to be torn down and cleaned out. The plates, over time, will get clogged with waste and will inhibit the ability of the filter to move water through the plate and up to the lift station.

The invention of the power filter and/or wet-dry filter has pretty much taken the spot of the old [acronym:2cff63bca1="Under Gravel Filter"]UGF[/acronym:2cff63bca1]. They are still used, but they are not nearly as popular of the filter choices I just mentioned. Go with a Penguin or Emperor Bio-Wheel solution if you are wanting a different filtration method. You won't be disappointed.

If we may ask, since you have an eclipse, why are you wanting to change the filtration method? I have an Eclipse 3 Hood mounted on my 40 gallon tall tank and love it. Not having everything in the world hanging on the back of the tank gives it a nice crisp look.

[TankGirl]

I have the Eclipse 12-[acronym:2b45964a9a="Gallon"]gal[/acronym:2b45964a9a] and the filter that comes in the hood is excellent, with the biowheel and everything. You just cannot beat this. If you do not have the hood, you can order it, I think Drs. Foster and Smith have it.

[brotherd]

Run away from [acronym:71acbad7d1="Under Gravel Filter"]ugf[/acronym:71acbad7d1] as fast as you can.Excellent bio filter but thats it.No plants allowed,lots of gravel syphoning,blah!Old school hardware at best.Leave it on the shelf and get a cannister filter to match your set up.