HOB versus undergravel filter

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Aquarium Advice Activist
Feb 10, 2005
Is there a difference in filter efficiency between HOB and undergravel filter. I sometimes even see a combination between the two. For which aquarium types or sizes is one to be preferred versus the other?
HOB's are definately more effectient than ugfs. I would not recommend a ugf for any tank. Even fry tanks I'd use a sponge filter or a mini hob.
HOB or canister, IMO, are better choices, and they are good enough as stand alone filters. No need to combine them with anything else, provided you match the size with your tank.
Ok. Now that I have heard that HOB is to be preferred, I am still unclear of the reason why. Is it the water amount that is being filtered or is it something else.

The 30 gal octagonal is probably still too small for a pleco, but other than guppies and platies, neons, corys, what else could be added to give it an overall colorful and evenly spread tank?

By the way, it is nice to be back.
UGF's are nitrate factories. They gunk gets trapped under the filter plates, even with regular vac's and nitrates go through the roof. They are more difficult to clean thoroughly as well. I've removed UGF's from tanks and was blown away by all the gunk that doesn't get vac'd out.
I would agree with what Zagz just said, they are nitrate factories, and can create anaerobic pockets in the system if not cleaned properly. And about the only proper cleaning is a complete teardown.

As for colorful fish, there's cherry barbs, various tetras, various rasboras, dwarf gouramis (if you get a couple, watch carefully for aggression), tiger barbs, and a few others.

As for cleaner fish, can do cory cats and otos. If you prefer a pleco, there are a few plecos that would work that don't get any bigger than about 6 inches. So there are a few different things out there you could look at in your decision making.
Yet another "Death to the UGF!" thread. UGF's are not necessarily bad. I have a ugf and a hob on my 20 gal. Everyone says they are nitrate factories but my nitrates are around 5 ppm, and I am downright neglectful of tank maintainance. Part of this is my live plants, but I have been adding nitrate fertilizer as well.

UGF's are not strong mechanical filters-they don't move enough water. UGF's are great biological filters-they use your substrate as biological media, and they are a good passive mechanical filter. My brother removed his ugf and he noticed a lot more stuff floating around in the tank and sitting on top of the gravel.

There are several excellent non-teardown ways to clean your ugf. I stick a siphon hose down the uptube and suck out ridiculous amounts of junk. If you have a ugf with a flat surface, clear a space of gravel and place your gravel vac flush with the plate and move it around on the surface.

UGF's are not great for planted tanks, especially for heavy root feeders. Their roots will grow under the plates and won't get the nutrients they need. In my tank, I have my root feeding plants in terra cotta pots with my brother's special potting blend.

My verdict-HOB with UGF is a good setup unless you don't like how it looks, don't want to run an air pump, you have root-feeding plants, or you have an incompatible substrate like sand. I would not use a UGF alone.

Well, all filters are nitrate factories. That is their very purpose, to convert ammonia into nitrate, which is less toxic to fish. Thus, the amount of nitrate is determined by the ammount of ammonia you put in (bio- load) minus any removed by plants and PWC's. Gunk trapped in an UGF can conitue to break down into more nitrate and other organic compounds that is not easily removed by vacuuming, but I do not think it is significant with good tank maintenance. UGF's require uplift tubes, with an airstone or powerhead. They do accumulate gunk underneath them, and thorough cleaning of them means a tank tear down, but they take years to reach that point. And they also work. In my opinion, HOB or canisters work just as well, are easier to clean, maintain, and repair, so why bother with an UGF? But if you like them, I have no objections.
Good points made by TomK2 and Apocalypse-Gold. I have one tank that has been running with a UGF for 12 years without tear down. A ugf with reverse flow powerhead, and HOB or cannister should be a very good solution in a non planted tank. The slight flow up through the gravel should help the other filters remove the detritus and reduce the amount of gravel vauuming necessary.
Thanks Tom2K, Apocalypse Gold and BillD for your info. I am a lot clearer now on the pro and cons of UFG and HOB.
That info is almost worth a sticky!
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