Re: CO2 reactor efficiency

>My question is:  Should I be thinking about a more efficient reactor? 
>Would a Dupla "S" or Aqualine Buschke reactor allow me to reach the 15-20
>mg/l range?

I can't answer whether you need one or not, but I use a Dupla S reactor on my 
200 gallon plant tank.  It's a reef ready tank with two internal overflow boxes 
that dissipate quite a bit of CO2 (or at least I think they do) and a large 
trickle filter.  I maintain a pH of 6.8 with a KH of 4 to 5.  A 20 lb. cylinder 
lasted about 2.5 months.  These reactors seem a little overpriced for what they 
are, I believe that a DIY version could be made for considerably less.