spiral_72 wrote:
I'd forget about the carbon (ya don't need that stuff) change about
30%
water and change 25% once every two weeks with the correct dose
conditioner. Any more and you'd be changing the water chemistry
radically (that's bad if you have fish). Unless you have a problem
with
the tank, water changes that often aren't required.

I agree with this advice. It doesn't sound like anything is seriously
wrong with the tank at this point and spiral's suggested schedule will
keep the tank running well.

In a heavily planted tank, are filters really required except for
asthetic purposes?

Sometimes yes. I have tried twice now to disconnect my HOT filter and
both times CO2 concentration has sky rocketed to the 40 to 50 ppm range
and O2 has fallen off dramatically enough for the fish to be gasping by
morning. Do I require the filtration it provides? Heck no. But I sure
need the bubbles and surface agitation. I'm still looking for an
alternate solution because I don't like the HOT filter but for now it
is the only thing maintaining the balance of O2 and CO2 in my tank.

But I suppose the root of your question was really about the filtration
filters provide and not about the bubbles. In that case no - filters
just trap valuable resources that could be better used by plants. But
who wants bits of stuff floating in their water? Aesthetics is what
aquariums are all about.

-Daniel