CO2 purity? & Lighting for single plants

 Subject: CO2 purity?

> CO2 is not very pure?  Is there differen't grades of C02? 
> The idea of not getting pure co2 is troubling to me, since I too
> had similar problems as the original poster with not being able 
> my pH.

There are at least two different grades of CO2 available, (I found 
out during a similar problem) Food grade, which is used in soda 
machines and such, and commercial grade, which is used in some 
welding applications from what I can tell.  The food grade is what 
you want.  

Subject: Lighting for single plants or small groups

> I read in a TAG article (not sure which issue it was) about a ch
> had evaluated several types of lights including track light styl
> halogen lights. What he found was that there are many types of l
> which have built-in parabolic reflectors which produce a fairly 
> focussed beam of light of very high intensity at a lower cost th
> fluorescent lights. 


> It also might make sense in a _paludarium_ because you could foc
> the light much more accurately on a small patch of _emersed_ pla

Actually, in my experience, the problem is the reverse... to get 
enough light down to the submerged plants without burning the 
emergent plants, which are much closer to the lights.


Karen Randall
Aquatic Gardeners Assoc.
Boston, MA