undergravel filter

I have never had a problem with UG's, but they are a bit out dated, and are not as good as newer filter models and designs, such as internal and external power filters. In preference I would go for one of the newer models as they are better, but I still have faith in UG's. They are certainly not the worst - but there are better out there.

Thom.

Part of the problem is the fact that the flow can often cause particulate matter to be gathered under the gravel. If people clean the UGFs every so often, that would be less of a problem, but it is a pain to do so (you must remove the gravel and then the filter), and larger fish can render these obsolete quickly because of their large volume of waste.

The success of the UGF relies upon particles being forced through gravel, so any uncovered gravel causes a pool of debris to form, which is not exactly the point of the filtration.

As Thom said, it is outdated, and there are some dire consequences if it is not properly maintained.

Generally avoid large, messy fish, as they will clog it all up very quickly.

May as well disconnect it now...the fish is going to overwhelm the system in no time, and he might start digging before that point is reached.

Most cichlids are inveterate diggers. As they dig, the expose the UGF plates, allowing water to pass thru more freely where there is little or no gravel. This renders much of the UGF useless.

Besides diggers, any fish that produce lots of waste may be poor candidates for UFGs.

A superior form of UGF is the reverse flow UGF (RUGF). This version uses powerhead to push water down thru the UGF tubes where it rises UP thru the gravel. This helps avoid the problem of fish waste being pulled into gravel and beneath the plates. Also, the powerhead generally are outfitted with prefilters to help avoid pushing crud under the plates. RUGFs still suffer from bypass when used with digging fish.

RTR's over-engineered UGF (http://www.tomgriffin.com/aquamag/rtrrfug.html) is a good solution to all the problems with UGF.

UGFs (& RUGFs) are economical filters, but they must be maintained. I run a couple RUGFs and they function well, but I prefer other, more easily maintained filters.

HTH,
Jim