i cant see why temp has any effect on co2 inrichment all ur doing is giving the plant the gas it needs to grow and live (if it gets to hot or cold do we all drop down dead????)
i think that having the feed above the plants is a good idea as the gas dose full to the ground but i would give it to them throw out the whole grow to shorten the finishing time. last time i used it, i grew three very nice ladies in 2 1/2 months.
keep it up you never know till you try.