Help, my first scrog grow: why are my leaves sick?

[Personal Stash]

3 plants, Nirvana's Papaya and Master Kush, both photo's and feminized. 3 weeks into flower. Soil: 2/3 fox farm, ocean forest 1/3 perlite and a cup of worm castings per gal. soil. Water: ro water and sometimes dehumidifier water. I recently(this week) stopped using dehumidifier water and started treating ro water with calmag 5ml./gal water.Water is ph between 6.2-6.5 I fed them nothing before flower except a worm casting tea 3 weeks back. I now, for 3 weeks, feed them Advanced Nutrients Sensibloom A&B at 30% full dose(around 250ppm tds). I have a 300 watt quantum board led, Grow Light Science 300, at 25 inches above canopy. My space is a 2' x 4' x 6' tent with 4" inline fan & filter and a 6" oscillating fan. Temp. around 80 f, rh 50%. I suspect either a magnesium or manganese deficiency from pics. of those I have seen. What do you think? Any and all ideas/guesses will be appreciated much.

 

[NuttyProfessor]

looks hungry (K) potassium looks to be needed more , , i would up the feeding to 60/70 % in flower

 

[Personal Stash]

I will up my feedings to 60%-70% as you suggest because I agree with you. Thank you for taking the time to look at them. I have a question about ro water. I understand I need to add calmag to ro water but how much? I am currently adding 5 ml calmag/gal ro water. Is this about right? I have found several people saying to add calmag to ro water but they never say by how much. Any ideas? Thank you.

 

[NuttyProfessor]

i would find out what ppm plants need, add the calmag to your water first before adding any other nutrients , , i do not really use cal.mag but i am guessing the ppm would get you close enough i think its about 150 to 200 ppm , start at the lower end and do a little reading before taking my word for it

 

[Personal Stash]

150 ppm sounds right; that's what I get when I use 1/2 tsp. per gallon water. I am not sure what you mean "find out what ppm the plants need". I normally ppm the nutes to around 800 ppm total, including the calmag. I have read anywhere from 600 to 1000 ppm so I just averaged it to 800. This is the final ppm, I start at around 200 when first start to flower and gradually work up. Are you saying I need to find out what ppm's these particular plants need because I have not seen that info anywhere?

 

[bluenoserjoe]

I think the professor nailed it with the potassium. A potential potassium lock out can be caused by to much calcium. You are currently feeding at 5ml/gallon. That is a little more then twice the amount that I am using,(2ml./gal) so maybe the problem.

 

[Personal Stash]

OK, that makes sense. I never could find info. on how much calmag to add to ro water but maybe I am using too much. Thanks for the reply.