"Tim B" wrote:

I found its instructions in PDF format on the web.

(1) It's only rated for 20 gallons. Does it seem like it would be enough
for 30?


Disclaimer - I'm far from an expert on these things, as I'm running my
first ever planted tank (20 gallons).

The effectiveness of the system would depend on the amount of CO2 gas
you're producing and moving through the diffuser. I'm using just the
Nutrafin diffuser with my own DIY yeast-in-a-bottle, not the whole
black 'tank' assembly. If I wanted to use it for a larger tank, I'd
simply hook up another yeast bottle to the same diffuser.

I'm quite sure the diffuser would serve a 30-gallon tank just fine.
The limit in the complete Nutrafin system is simply the amount of CO2
it can produce. It looks to me like that's about the same limit that
any yeast-based CO2 system would face.

(2) It has two separate packets of stuff that have to be replaced monthly

This is a key reason I went with the DIY for the actual CO2
generating. Yeast, sugar and water are a lot cheaper and more
convenient.


--
www.ericschreiber.com