Using or not activated charcoal is a matter of your personal opinion and judgment. I keep activated charcoal in all my tanks, except if:
a) 3 weeks go by and I don't have the replacement bag, the old one is removed and the tank stays without charcoal media (keep in mind in Santo Domingo sometimes
LFS run out of stock for a good while). I have used cheap activated charcoal to refill some of my filters, but now I usually wait for the replacements to arrive.
b) My Angelfish tank, with peat filtration, besides keeping
pH at 6.8, it provides the tea-colored water these fish love. If I place activated charcoal the tea-colored water is gone.
c) When using medication in the Hospital tank, since activated charcoal can reduce efficiency of chemicals diluted or suspended in the water column.
The main reasons I use activated charcoal: tank's water smell more "neutral" and looks "clear" whit it in the media.
All my tanks are planted. I guess charcoal helps there too.
Pepe
Santo Domingo