I am tryin dwc and to help control res temps I have a PC fan blowing on my res. I also use co2 with the bottle and yeast method. After every hour of intake and exhaust being on they shut off for half hour to allow plants access to the co2. Since my res fan is sucking air from inside the grow room where there is co2 present and blowing it into the res Wud that affect anything ? Wud the extra co2 harm the roots? Shud I add another fan to take co2 out?