Should I remove my UGF?

If you are going to remove it - remove it all. The debris will just get trapped under the plates and over time will lead to high nitrates and possibly those pockets of toxic gasses. If you have been very consistent with weekly large water changes, and deep gravel vacs you shouldn't have any problems. You should also run your new filters for a couple of weeks before you make the switch to get them well seeded.

Drain a bunch of your water into a big bucket or plastic storage container and put your fish in the bucket while you do this. You could also add an airstone and heater to the bucket. Pull the mess out. Let every thing settle and do a gravel vac. Replace the dirty water with your conditioned clean water, make sure the temperature is right before you add the clean water back in. You are trying to keep the beneficial bacteria alive in your gravel. Then slowly acclimate the fish back into the tank.

If you have NOT been consistent, start by doing very small partial water changes and small sections of deep gravel vacs. You might want to do a search here on 'old tank syndrome' before you begin. One way to tell if there might be big problems is to do a nitrate test... Until your numbers are down into the low 20's, don't do anything.

I am sure other's will jump in here with added advice.

Cathy

When I removed mine from my tank, I took out everything. I had been having problems with the crud under the plates keeping the Nitrates up. The UGF was the water intake for this system, two HOB's had their pickup tubes connected to the UGF.

I moved the fish, and took the plates out. It was a real mess, but once it was done, I had no more problems with the water in that tank.

Unless you have a way of cleaning out under those plates, I would definitely remove them. There's undoubtedly some gunk under there. If you leave it, it will just sit there and decompose...

I did this to my tank a few months ago... the guys are right, definitely take everything out. Start by doing small gater changes and gravel vacs, and then when you think your gravel is as clean as it is going to get do the change. I put my fish and plants into a cooler for the day, as it was the only thing big enough, and slightly insulated I could come up with.

One thing to add, be sure to seed your new filters before the big day in order to hopefully prevent a massive die off of beneficial bacteria. Also, be sure to do frequent water changes afterwards until things settle back down. It took me two weeks before it started looking "normal" again.

ugf's generally work best in smaller tanks, in my 10gal freshwater the nitrates would almost never go over 20, even if i forgot to do a waterchange for two straight months... (not adviseable... but its not really my tank, and i was seeing if the fish would die if i left the care to the owner... who should have been doing the water changes... but the parameters never changed..)
that UGF was amazing, and if yours works as well id not remove it, if you experience problems like higher nitrates and gas pockets, dig it up or add a canister, puging the outflow into the tubes and having a reverse flow ugf... you'd then have to use the canister for mechanical filtration, and yiou would still have the biological filtration of the ugf

i have UGFs on my tanks, and they work best when used with a HOB filter or canister.
during water changes, just turn everything off and wait for the water to stop moving, and then if your water siphon is strong enough, you can suck all of the debris through the plates.
or just get some reverse flow powerheads so the debris is flowing up though the gravel and then into the HOB or canister filter

a UGF is one of those debates that go back and forth.
they keep the toxic gas pockets from forming and they provide really good biological filtration
but they can become nitrate factories if you dont clean under them every once in a while and they need to be used with either HOB filters or canisters

It's interesting because I have a 125 gallon that I have been thinking exactly the same thing about. I have not had problems with nitrates or nitrites but I wouldn't mind getting rid of the tubes and powerheads either. I have been considering a RUGF but have not made the change yet. I have always had good success in the past with UGF's and I have not been ready to unearth my whole tank so it is still there. Question for people with both setups: do you fel you have to vacuum deeper or more completely with the tanks with no UGF (to make sure you get ALL of the gunk)?

My gravel doesn't seem to get as dirty as deep now with out the UGF. I suppose now since there is nothing sucking the gunk it down deeper, it just sits at the top.

It was a horrible job to do, but I am much happier with out it in the tank. No more tubes and pipes. No airstones to run. I made the change to an Eheim canister, and I don't even have to change filter pads or maintain the canister very frequently. I used to hate cleaning out the vertical tubes and replacing the heads every few weeks.

i dont know how they work on the larger tanks, but the one that was in my ten gallon was not touched for around 5 years and it ran as described in my last post, it did run with a hob and had a deep bed (3 or 4 inches) of fine gravel.
all i needed to do as far as upkeep was to do a good gravel vac every other week
it was the easiest tank that ive ever taken care of, i wish that my other tanks were as easy...

Well, have been running 4 UGF plates linked by a common manifold to a Magnum 350 canister (350 gph flow) for a year on my 100gal tank. Zero on NH3, NO2, and NO3 stays really low. If anything accumulates, it's usually no thicker than a piece of bond paper. I'm using an additional Magnum 350 for the water column with a sponge over the inlet.

Not much accumulates under the plates. I'm using both large and small species of MTS since mid-summer, and they keep the gravel really clean...I don't pull up near as much stuff during monthly gravel vacuumings now that the tank is seeded w/ thousands of little MTS (I do weekly 15% water changes, but sometimes these turn into bi-weekly).

The UGF debate will rage on for years. I agree that powered UGF systems are superior to airlifts.

Strangely, my Amazon Swords, tons of Hygrophila Polysperma, and bunches ofJungle Vals root nicely in spite of the UGFs. I stared with single specimens of each, and they are proliferating like crazy, and are usually in need of constant pruning. The Amazon Sword was added recently, and is already budding off a new bunch. Then again, these are tough plants to kill.

v/r, N-A