In our 48 gallon tank at work I've started to inject C02. I'm doing the DIY
method with 2 2L bottles. Unfortunetly, I can only sustain a c02 content of
about 15ppm for a couple days and then it dies off. The floor where the
bottles sit is concrete, and there is a hollow space under that floor as
well (cool air underneath). Are the bottles cooling off too much and
hindering effective C02 production?

Or is there something wrong with the recipes. We've tried many different
measurements of sugar and yeast...even 4 cups of sugar to about a teaspoon
of yeast. It seems to fizzle out really nice and fast for the first few days
and then peters out. I'm sure the sugar isn't used up THAT fast.

Any suggestions for DIY for bigger tanks like 48gallon?
Thanx!!!!
--
Dave Picklyk
www.picklyk.com/aquascape