Hydronics 1 month into flowering - "Showing some yellow leaves.."

[Canname]

Hi... curious if i should make any move.

I heard because I use a 120W
(https://www.migrolight.com/product/migro-aray-120w-ii-bar-light/)

I should not follow certain high PPM tables because my light is less strong.

Its' beginning to show some yellow leaves..

Trying to keep: 5.9pH and 750ppm


What would you guys recommend to do. Not unhappy with the result of-course. But would not mind doing what is necessary to get the best yield.

Thanks

 

[Cloud]

Can't keep ph at 5.9 because plant can't absorb some nutrients that good. Need to let it drift between 5.5 and 6.5. Looks like cal/mag deficiency.