Beginning Hydroponics

We have two grape ape plants in 2.5 gallon General Hydroponics power growers with a clay medium in our room under 18 hours of light and ventilation. We are using General Hydroponics Flora Series. They are in their seedling stage and I'm using 2.5 ml per gallon of the solution. The leaves our curling and our ph keeps climbing after it gets down to about 6 to over 7, which I feel is unsafe. Am I always going to have ph problems. Is this common? We've been using reverse osmosis water. Also I have flushed the system out. Was that a mistake. Also, we have two air stones in the bottom to boost oxygen in the water. Is this recommended? Please help, I'm new at this and worried my plants will die.

Im no expert but, I think thats pretty much normal considering the small water res that you have....I have seen somewhere that a .7 per day drift is average, thats why I prefer a bigger res, and even that drifts like .7 some days, and nothing other days...Also, I have heard a pretty key piece of advice here: "When in doubt, flush it out.. So no, I dont think you were wrong to flush.. Another key piece of advice I know to be true is that an h2o2 mixture to your res can do wonders regarding nute uptake...Also, 5.6 (Ph) is usually is a good starting ph unless your plant strain specify's other.

Smaller res's are subject to frequent ph changes, I think thats just the way it is, maybe Im wrong..