I just put my seedlings in my ebb and flow system. It only has 8 gallons in the res. my problem is every 2 hours I check the ph, and it is low.....around 5.0 . So I use ph up to about 6. And it falls back down. It makes my ppm go up and right mow they are at 800 ppm. For my general hydroponic nutes schedual, it says to start seedlings out at 300 ppm and mine are at 800ppm because of all the ph up ive used... What can I do?