help. cal mag problem. week 8. pics

Week 8 of flowering my leaves are turning light brown. Calcium magnesium deficiency I think. When I filled my reservoir I did not add Cal Mag for the first weeks. I use RO water and was not aware that I had to add calcium and magnesium. I have 4 different strains in this Bin 8 weeks to 12 weeks. can I add calimag now to my solution without harming anything on my next water change?

That's a tricky one, you can but be careful. Here's what I mean. If your target ppm is 1650 and your there w out the calmag then you may want to drop the ppm 1st. If target is 1650 and your sitting @ 1225ish( I use 425ppm calmag 4 weeks prior to harvest) then add away

Week 8 of flower? You should be using Mag Sulfur not Cal Mag.
Cal mag is for vegetative growth up to the second week of flower.
Mag Sulfur is for week 2 to harvest.

Hope that helps.

Oh yeah, you should click here too, for a uptake chart for the right pH.

You are using LED which usually means plants needs Calcium supplemented until the last week as a certain red nanometer sometimes makes them take Calcium up more and lack of it can lead to big problems.

Foliar feed once only with 2ml/L and supplement every feeding.