Backyard Aquaponics
A place to discuss aquaponics

after about two weeks, my zucchini and yellow squash are going limp and dying. Am I watering too much? Too little? Or is this just the GA heat getting the best of my plants? My Ph is stable at 7.5.

Photos are needed mate, I can't help you but the experts here may.

Not sure how you would water too much.

I can tell you that I had a really hard time getting any vines to get going. Finally got some to hold but not growing as vines. Mostly as bushes though they are starting to flower. I also started one or two by seed to see if those work better.

My system runs flood and drain during the day and constant flood at night.

Definitely need pictures

I'm a couple hours east of you near Statesboro and the heat is starting to kick in. With that said all my plants are doing good, both AP and dirt. You might have a beetle or worm in your plants. Take some pics and share what they looked like when they went bad.

Look for squash vine borer's. Tiny holes usually near base of stem with saw dust type particles.

Photo would help a great deal.
"Zucchini plants prefer soil that is slightly acidic or neutral with a pH of 6.5 to 7.0, and as heavy feeders, nutrient-rich soil is ideal." http://homeguides.sfgate.com/newly-planted-zucchini-turning-yellow-76562.html
Maybe the 7.5 pH is too high.