Brown spotted leaves

[BC Buddy]

On my first hydroponics grow. In the fourth week of flowering.
Ebb and flow using hydroton and LED lights.
Four White Russian plants. Three are very healthy but one has many leaves as in the attached pic.

I've checked many threads but am not sure why this plant is browning.
Suggestions, please.

 

[The Hemp Goddess]

What pH are you running?

 

[BC Buddy]

I check pH daily.

Min 5.5

Max 6.6

Average 6.01

Current 6.0

Thank you for your prompt reply.

 

[The Hemp Goddess]

I would try to not let it get much above 6.0. There are virtually no nutrients that it can uptake at a 6.6 pH. If you are spending too much time at 6.0 and above, it is probably locking out some nutrients. I always like to let mine drift from about 5.4 to about 6.0.

What nutes are you using? I always ran DWC--never had as good a luck with ebb and flo as I did DWC. How many times and how long are you flooding the table? What is the temp of your res water?