What type of hydro system is it? Ebb n flow, bubble buckets, NFT?

If you're in a bubble bucket, you might have more serious problems... I've only had plants that were droopy when they needed water... ebb n flow and soil. Make sure they're being properly watered and your airpump is running properly. Maybe the filter's clogged on the pump and it's not pushing out as much air as it should.

I'll bookmark you and check back in a little while.

Hope we can help solve the problem...