The growth rate of discus will vary according to such factors as tank size, water quality, and feeding regimen.
If you plan to operate the filter at all times,
I think it would indicate to me a breakdown
of some kind in your discus program. A good
idea would be to treat a diatom filter as you
would a 100-dollar bill folded up in your
wallet—to be used only in a big problem or
in an emergency.
Regarding plants in your aquarium, I
seldom use any in our discus tanks, so I’ll
comment here on the few plants I have used.
Yes, plants of the Echinodorus genus are very
acceptable. Many species of Cryptocoryne
can be found in planted discus aquariums,
and those with broad leaves are found to be
good for female discus to deposit their eggs
on, though I’ve never had much success with
any of the Cryptocoryne genus.
In nearly all cases when the hobbyist
employs both discus and plants in the same
aquarium, the number one priority is the
fish—not the plants.
When visiting discus breeders in Auckland,
New Zealand, I found that several of them
were growing water sprite (Ceratopteris) as
a floating plant in their discus tanks. With
reflectors over the tanks, the breeders all
found it necessary to “thin out” these fast-growing plants frequently. Also, the water
sprites were found to quickly “settle down”
newly arrived discus. If anyone attempting
to grow Ceratopteris, either as a floating
plant or potted, finds it is not growing well,
they can probably be certain the water is not
suitable for discus.