CO2 vs. Flourish Excel

[tankenvy]

I've searched and read a few threads on this, but still have questions based on my own set-up.

I have a 20g tank with 1.5 wpg, heavily planted with mostly low-light plants (Java Fern, Anubia, swords, crypts). Plants are showing extra growth and greening up nicely since I started adding Flourish Excel, Flourish Potassium and Flourish Comprehensive, according to labeling. I also added Flourish substrate tabs (mostly an iron supp?) for the swords.

My question is this: if I stick to low-light plants, would they do even better if I added a low-cost CO2 system such as the Red Sea CO2 Bio-Generator or Hagen system? Or is Flourish Excel sufficient?

Related question: If I stick with the Flourish Excel and ferts, what's the biggest limiting factor for optimum growth of the plants I currently have: the available CO2 or light?

Thanks!

My tank:
20g, 1.5 wpg
Latest water test--nitrates, nitrites, ammonia neutral. pH 7.0 (but tested just after a 40% water change).
KH: 55 ppm (tap water's soft around here)
Dissolved CO2: ???? (best way to test?)
2 otos
3 corys
3 lemon tetras
3 rummy-nosed tetras
1 million snails

 

[phanmc]

A yeast CO2 system would be better than Flourish Excel and more cost effective longterm. Whether the additional growth is noticeable will depend on the plants. Slow growers like java fern and anubias are hard to notice while stem plants like hornwort and anacharis will show improved growth almost right away.

If you stick with what you have, CO2 and light will both factor equally as the limiting factor.

 

[Mgamer20o0]

if you stick with low light plants you prob wont need co2. co2 gas will always be better then excel. red sea and hagen's systems are just diy co2.

whats limiting your plants now is light. then co2 then ferts.

what kind of lighting do you have?