im not sure but i bet you can control it separetly
look into blumounts auto drip system i hear they work magically
http://www.blumat.at/automatic-watering-system.php
before you go wtf
i have to say that link is the wrong one . . . give me a day ill be back with the right link someone on another site uses the ones im refering to for hydo drip in coco and i cant find the ones i mean rigth now they are definelty pump feed and not auto like that link but interesting i have some auto i might throw out side to do that to