uhm, i disagree with your lfs
. I have the grey cansiter on my ten gallon and its a small jungle. I have great growth in all my plants in there and its because of the co2
addition. Now, you don't have to buy that $20 set up. You can just as easily do a DIY
set up for a 10 of 15 gallon for a fraction of the cost. The hagen set up isn't very useful after about 30 gal
. I know people on this site have used the hagen for small tanks like 5.5 gal
or 10 gal
as for excel, yes, it can be useful for a 15 gal
. but I think for the best success, you have to dose it everyday or every other day, without fail. I used it on my 10 before I got the hagen. It worked to an extent, but I think the hagen does a much better job.
search the site a bit, you'll see lots of folks use hagens or DIY co2
for small tanks.