Hi everybody,

I have a 25 gallon Aquarium populated by Mollies, 4 of them at
the time (2 adult (one of them born in the tank) and 2 young (2 months
old, born in the tank)).

I have never been able to keep the plants in the tank beautifull or
even living for a period of more than 2 or 3 weeks. They all wither
and die very rapidly once planted. It looks to me as if the roots or
the bases of the plants near the root outside the gravel are rotting
(althought that might be too strong a term). I've had 6 different
varieties of plants, none of which survived very long. My fish seems
to die a little bit too much also, although the salesman at the local
fish store tells me this is normal.

Here are the results of the most recent test:
PH: 8.5
KH: 60 ppm (about 3.4, I beleive is the correct conversion)
GH: 80 ppm (about 4.5, I beleive is the correct conversion)
NH3/NH4 (ammonia): around 0.6 ppm (test kit doesn't give super
precise result, so it's around 0.6ppm or maybe a little less)
NO2 (Nitrite): 0.1 or less ppm
NO3 (Nitrate): 5 or less ppm

Neon is open 12 hours a day. No CO2 is added in the tank.
I make a 25-40% water change every 7 to 9 days. Tap water is used for
that purpose.
I add some tap water conditioner (Nutrafin's Aquaplus) and a nitrifier
(Nutrifin's Cycle) everytime I make a water change.

So, what can I do in the immediate to remedy the situation, and what
can I do in the long term to make sure this situation doesn't arise
again?
Thanks a whole lot for any help.