I am on week 5 and 3 of late flowering and my plants are turning yellow and showing brown spots. I looked up the diagnosis for my plants and it seems to be a magnesium problem so in order to fix it I have been doubling the amount of cal-mag. But it seems to be either locking out the plant or causing nuts burn. I read some where that epson salt is something that can be used to fix this problem but I am not sure how much to use or if this is truly a magnesium issue.
It looks like a mobile nutrient issue (new growth is good, deficiency showing on old growth). This could be Mg deficiency. (Ca is immobile)
If you have Cal Mag you can mix a spray. I haven’t done it in flower but in veg I spray/drench mine and let them dry away from the grow light so it doesn’t burn them.
As far as Epsom Salt, I have used a tsp with Recharge mix in a quart of dechlorinated pH-ed tap water.
I think you can also distill water. Boil water with a empty pot in a pot of water with the lid upside down on the main pot. Slow process but quicker than 24 hours. Putting ice in the lid speeds it up a little. There are videos of this on the tube etc. You could also just boil but I think it doesnt get all the additives out of tap water.
I am new here so not sure about the amounts. Everything Ive read says to let the water sit for at least 24hrs or more to remove the bad additives when using tap water. In a pinch I know you can distill rather than wait.
One other thought: Some municipalities may use chloramine vs chlorine. Chlorine off gases by itself chloramine doesn’t. Using a granular activated carbon (GAC) filtration system is the most effective way to remove chloramines from water