Is this a potassium deficiency?

[deptrai]

Pure AK grown in FFOF soil with GH Flora nutrients. About 45-50 days into flowering. One 180w UFO LED + four 65W CFLs in a 2' x 4' x 7' tall tent in the garage. Temps and RH have mostly been in good ranges. Lots of ventilation. I suspect a potassium deficiency due to low PH causing a nutrient lockout. I have a real hard time judging the color on the PH test kit. The yellow/green are hard for me to distinguish. I guess I need some type of meter to get an accurate measurement.

Anything I can/should do now? I think I'm about 14-20 days from harvest.

 

[Kalimaki420]

Looks like Cal-Mag.

With LED many plants need a bit more of that.

 

[Vestrimatrik]

Looks like Cal-Mag.

With LED many plants need a bit more of that.

We'll son of a wish i would have learned that sooner.
I'm experiencing the exact same issues under Cree COBs and now that I know this bit of info I can stay on top of it.

Thanks Darkgrow!

 

[AngryBird]

Well post a picture of test result and we can help you figure it out