No free lunch. The pores on the block get filled up after a while and it
looses it's effectiveness. You have to replace them after about 6 months.
I changed to DIY CO2 and I think that works much better, and is certainly
cheaper. CO2 tanks are fine, but my 5 year twin girls like to help and mix
the CO2 bottles so we have more fun with that around our house. Cool fizzy
stuff. The girls call it Fish soda pop.

Chris.