PH issue with Advanced Nutrients

Alright, I've got the seedlings (growing their second pair of leaves) in the bubbler and I added Advanced Nutrients at 1ml/l, but the water PH still rises to about 8. Hardly it's the rockwool this time?

use ph up and down but...or spend the extra and get ph perfect advanced nutes

These very much ARE PH perfect. That's why I think I've got an issue. And I've also tried with vinegar, but it still rises from like 5.7 to 8 overnight.