i leave the system flooded all the time

[cbharp]

hey, I built your 11 plant garden Ron and it works great but when i started the setup the plants were doing nicely then after i rinsed out the water with the grow minerals in it and put some fresh nutrients in there the leaves sides on the older leaves are curling up and turning yellow! my ph is at 6 i leave the system flooded all the time with a pump to keep it circulating. and right now Im at 24/7 light but i thing Im going to cut down a little bit what do u guys think i messed up with?