# Will this work?



## cichlidmama (Sep 7, 2005)

Found this on a website, I think it is interesting.



It is an under gravel filter with two holes on the bottom of the tank, so waste collected by the filter will go to a mechanical filter.

Thoughts?


----------



## moto_master (Jun 23, 2006)

I've thought about doing this myself. To me it looks like your design has you drilling holes in your tank. I was going to hook a powerhead up to the tube that connects to the undergravel filter, and that would suck it out. But I thoughts were that the mechanical filter would get clogged up rather quickly, and would require a lot of maintenance. If you do it, take pictures and let us know how you like it.


----------



## Mcdaphnia (Dec 16, 2003)

This design would work only with a cannister or other sealed filter without a modification rerouting the water to an anti-siphon device before going to an open filtration system such as a sump. If the UGF has the right flow rate through the properly sized gravel bed of the right depth, there should be very little debris reaching the cannister filter. However that is a big if. UGF's are rarely set up properly, so adding a tee valve to allow backflushing the cannister (without backflushing into the gravel bed) is a good idea.


----------



## cichlidmama (Sep 7, 2005)

Mcdaphnia said:


> This design would work only with a cannister or other sealed filter without a modification rerouting the water to an anti-siphon device before going to an open filtration system such as a sump. If the UGF has the right flow rate through the properly sized gravel bed of the right depth, there should be very little debris reaching the cannister filter. However that is a big if. UGF's are rarely set up properly, so adding a tee valve to allow backflushing the cannister (without backflushing into the gravel bed) is a good idea.


Not sure if I understand the complication. After seeing this drawing, I was thinking of allowing the UGF to function primary as biological filter with the external filter as mechanical, I was thinking of using a Magnum 350.

I am confused with your suggestion though:


> so adding a tee valve to allow backflushing the cannister (without backflushing into the gravel bed) is a good idea.


----------



## Mcdaphnia (Dec 16, 2003)

If the filter is not a cannister filter, the tank can drain out completely or if the pump returns water faster than it drains out of the tank, the tank could overflow. With a cannister filter, the exact amount of water returns as is pumped out.

A tee valve is one that redirects the water flow, so that if you pump water backwards through the filter to rinse (backflush) it, you rest the valve so that the water goes to a drain or bucket through a length of hose instead of back up into the tank. Some cannister filters have a backflush system built in, and in those the backflush hose is attached to a special fitting on the filter itself.


----------



## cichlidmama (Sep 7, 2005)

got it Mcdaphnia and thanks.

what do you think of using ugf as bio and mag 350 as mechanical? Do i get it backwards that ugf should be used as mechanical and have a canister filter as bio?


----------



## BillD (May 17, 2005)

It would work better if the flow went the other way. It would then not need a hole in the tank, and the gravel would not need cleaning.


----------



## aaronc (Mar 2, 2009)

Most tanks have tempered glass on the bottom. Cant drill them.


----------



## Mcdaphnia (Dec 16, 2003)

aaronc said:


> Most tanks have tempered glass on the bottom. Cant drill them.


 That is a good point. You might have to search for an older tank before the tempered glass became popular, or replace the bottom with a thicker untempered glass panel, or with granite. Even if you are going to replace a tempered bottom, don't break it. They can make a huge mess.

The advantage of this design is the absence of hardware and pipes in the aquarium. A return spray bar could be invisible and there are inline heaters that could remove the last bit of needed equipment from the tank.

It does not matter much whether this is a reverse flow system or not from an effectiveness point, but reverse flow would reintroduce some visible plumbing to the tank. Both systems and both the UGF and the cannister are pretty much stuck with being bio filters. Mechanical flitration is either a mat or some other unit that can be removed several times a week and rinsed clean or replaced with fresh. If you use a gravel cleaner often, it will be your mechanical waste removal system. With high waste producing fish, a power filter, box filter, or sponge filter that can be cleaned out often will help. Digging fish will interrupt the UG filter, one reason they stay unpopular with cichlid keepers who keep digging fish, or with fish like oscars and discus who clog the gravel one way or another.


----------



## toffee (Feb 11, 2006)

Let me be the first one to try this idea. I happened to have a 30" 20g long glass tank that has a 1/2" hole on the bottom, right in the middle in fact. I was intrigued when I saw the drawing.

I am planning to use it as a turtle tank with lots of waste. I can either leave it bare bottom with no substrate or do as the drawing with a UGF. I am leaning towards ugf.

Ponds use bottom drain to do heavy lifting cleaning of debris so I think it should work on aquariums also.


----------



## toffee (Feb 11, 2006)

The know issues of ugf:



> The argument against under gravel filters is that over time, the gravel gets clogged with debris and flow rates decrease, thereby decreasing filtration and allowing a buildup of waste in the water, reducing the water quality. Furthermore the restriction in water flow through the gravel will allow anaerobic pockets to form in the gravel, which can promote the colonization of harmful bacteria which can potentially poison an entire tank. Additionally, an under gravel filter provides only biological filtration and poor mechanical filtration, and can only provide chemical filtration for short periods, and at the cost of reduced efficiency of both the biological filtration and mechanical filtration provided. In some of the extreme cases reported, loss of power for a few hours has resulted in entire tanks crashing, killing all the occupants of the tank!


so - clogging!



> Now, it is true that under gravel filters do not provide high-quality mechanical filtration, and that the use of the carbon or resin inserts for the lift tubes will only provide short-term chemical filtration and will greatly reduce the flow through the system, thereby reducing the effectiveness of the filter overall. Furthermore, if your under gravel filter is run with power heads mounted at the top of the lift tube, rather than with air stones and an air pump, you do not even have the option of inserting these carbon or resin cartridges, thereby eliminating the option of even partial or temporary chemical filtration through the under gravel filter.


With the bottom drain and use of a external canister, this is a non issue.



> However, when proper maintenance of the under gravel filter is provided, the filter is a proven, long lasting, inexpensive, and low maintenance filter. The maintenance that an under gravel filter requires is regular cleaning of the gravel. I recommend that between 1/4 and 1/3 of the gravel be cleaned with a gravel vacuum with each weekly 10-15% water change. This will remove the debris from the gravel and prevent the gravel from getting blocked up, allowing free flow of water through the gravel and preventing the development of anaerobic pockets that can harbor harmful bacteria.


With bottom drain and a strong canister, I think all one have to do is stir the gravel some every week with the filter running?

Thoughts?


----------



## Mcdaphnia (Dec 16, 2003)

toffee said:


> The know issues of ugf:
> 
> ......
> 
> ...


I think all the UGF issues you quoted are exaggerated, special case examples presented in a very biased argument. It's like the stuff in a commercial before the mumbled disclaimer at the end. There are some very good reasons not to use UGF in particular cases, some already mentioned in this thread, but the quote above is just a sales talk trying to get you to buy into something else.

Stirring the gravel bed periodically should be good, but I would do it while bypassing the cannister and draining out water from the system through the bottom to make room for a water change. That way excess detritus does not end up inside the cannister.


----------



## toffee (Feb 11, 2006)

Mcdaphnia said:


> toffee said:
> 
> 
> > The know issues of ugf:
> ...


You got a very good point there, draining while stirring the gravel is a good idea, Sure make water change a lot easier.


----------

