Hi There, If you are using an air stone in the reservoir this is not advisable ….. as you are not adding air to the water as the bubbles simply break on the waters surface….. Also there is a chemical reaction by doing this and the effect is that the pH in the reservoir increases. Also is the air you are blowing into the base of the pots via the airdome warm 18-21oc….. what are your environmental conditions….. temp and humidity in your growing area ???