Geranium question

[stanley550]

Hello everybody. I am trying to grow Geranium hydroponically. Its a bit of a challenge as it really doesn't like to be over-watered.
At this point I have it in a small vase, with hydroton and a drip system. I'm using a small aquarium pump to siphon water from the bottom of the vase into the drip nozzle on top of the hydroton.

The setup works fine, however I'm not getting best results. At first I left the drip system running 24/7. On the second day my geranium's leaves started to turn yellow. Second day I had to cut away two of the older/lower leaves as they were starting to really rot. At that point I started to turn on the drip system only once a day for 15 minutes. The geranium is doing better, as the leaves stopped yellowing. However the bloom of the flower is slowly dying. It had a few flowers blooming, and a whole bunch of them haven't opened up yet. So now they are all just shrinking and shriveling. They are trying to open up, but the petals are all very wrinkly and sickly looking.

The geranium is standing on a window sill, it gets a lot of sun in the morning, and the rest of the day its not really in the shade, but it doesn't get direct sunlight either. I'm checking the ph balance and its quite stable around 6-6.5. I'm using Botanicare's Pure Blend Pro Grow.

The hydroton is in the net pot, and the net pot is in the vase. Vase holds very little water though, maybe a couple of cups. Its a small plant though.

I can see some new roots growing in the pot, some of the roots are brown, some are healthy white.

I have the pump connected to the siphon drip and a small airstone inside the vase. Before both of them were on 24/7 (drip and airstone), but now I manually plug the air into the siphon in the morning for about 15 minutes, and then unplug it, and plug it into the air stone, and leave air stone bubbling for the rest of the day.

Has anybody tried growing these flowers hydroponically? How do you deal with "dry" flowers, without over-watering them? Are there any "general" rules for feeding schedule?

Also, about an air stone... I understand its best to keep it on for 24/7, but in my setup, the same air pump is driving the air stone, as well as the siphon for the drip. I don't want to have two pumps per plant. So would it be ok to just have the stone bubble while the drip is on, and then have still water in the reservoir, until next feeding?

Thank you.