Thomas Barr says:
Grow a tank with a UFG and sand.
Then try the same tank without the UF and add something like soil or Flourite with no flow.Now you can tell me which will have nicer plants?
Also, considering the loss of usable tank space, addition of lift tubes, initial cost of the UGF, added air pump or powerhead and it's electrical consumption, which do you think would be better? Why?
What I've seen: I have done this and have seen the differences. I kept UFG's and switched after seeing the difference between C/PVC grid style UG filters over traditional plates. Later, I saw the difference between this (RFUG's) and Flourite with no flow.
Now while you can have a plant tank with UGF and RFUG, the tank will look better, easier to maintain, cost less in the long run, and produce better growth without a UFG if you use some of the other substrates like Kitty litter, soil, sand+laterite or flourite etc.
Kitty litter and RFUG did do pretty good surprisingly.