Commercial UG plates, powerfilters aka HOBs, and canisters are all about the same age, a paticularly rich era in the late 50s and 60s when submersible/waterproof pump were maturing. Prior to that it was box fiters or HOBs which were air-driven. Non-submersible magnetically-linked drives were developing at the same time.
Along with the myth of UGs being outdated, the myth of UGs not serving as mechanical filters is one of the most wrong-headed in the hobby. The whole design flaw of conventional flow UG is that the filter served entirely too well as the best available mechanical filter. UG filtered tanks almost always were clearer that HOB or canister filtered tanks. But then folks did not bother to vacuum them well or routinely so they became loaded with mulm - not a good thing. Some folks even argued that vacuuming was harmful to the biofilter! Any unmaintained filter is a time bomb. All formats will eventually clog and go foul if the proper upkeep is not done.
Submersible pumps on which the flow can be reversed are among the least efficient units on the market when in reverse mode. I like AquaClear pumps in conventional mode, but in reverse the flow is pathetic. Test for yourself if you own one. The only pumps I will use for RFUG are Penguins with their reverse flow kits, which allow the pump to still operate in normal direction when coupled to the UG and provides a matching prefilter.
But I am quite confident that the endless discussions of undergravel filters will outlive me, and most of the arguments will be based on either hearsay from folks who do not grasp the need for vacumming any unplanted tank routinely, or by folks who have operated a conventional UG improperly. They are not for everyone or every tank setup, but then no filter format is. We currently have an embarrassment of riches with filter formats. Each has its own strengths and weaknesses. Those who will not or do not wish to think beyond HOB will survive, and so will their tanks and fish. But there are multiple alternatives - I use quite a few different formats myself, normally trying to match the filter type to the needs of the particular setup. I do believe that it makes my tanks better and in the long run easier to maintain. When any hobbyist moves past a single community tank, they might well benefit from exploring some of the other formats.
Along with the myth of UGs being outdated, the myth of UGs not serving as mechanical filters is one of the most wrong-headed in the hobby. The whole design flaw of conventional flow UG is that the filter served entirely too well as the best available mechanical filter. UG filtered tanks almost always were clearer that HOB or canister filtered tanks. But then folks did not bother to vacuum them well or routinely so they became loaded with mulm - not a good thing. Some folks even argued that vacuuming was harmful to the biofilter! Any unmaintained filter is a time bomb. All formats will eventually clog and go foul if the proper upkeep is not done.
Submersible pumps on which the flow can be reversed are among the least efficient units on the market when in reverse mode. I like AquaClear pumps in conventional mode, but in reverse the flow is pathetic. Test for yourself if you own one. The only pumps I will use for RFUG are Penguins with their reverse flow kits, which allow the pump to still operate in normal direction when coupled to the UG and provides a matching prefilter.
But I am quite confident that the endless discussions of undergravel filters will outlive me, and most of the arguments will be based on either hearsay from folks who do not grasp the need for vacumming any unplanted tank routinely, or by folks who have operated a conventional UG improperly. They are not for everyone or every tank setup, but then no filter format is. We currently have an embarrassment of riches with filter formats. Each has its own strengths and weaknesses. Those who will not or do not wish to think beyond HOB will survive, and so will their tanks and fish. But there are multiple alternatives - I use quite a few different formats myself, normally trying to match the filter type to the needs of the particular setup. I do believe that it makes my tanks better and in the long run easier to maintain. When any hobbyist moves past a single community tank, they might well benefit from exploring some of the other formats.
to see how much ewwy, gooey, yucky gunk had accumulated under there in just a matter of weeks, even when I gravel-vac once a week! I'M NEVER USING UG FILTERS AGAIN!!! 
