Need some help diagnosing a sick plant!

Hey guys I got three 7 week old feminized photo period cherry pies, potted in 7 gal fabric pots folded to around 5 gallons. Using reused fox farm ocean forest soil (used 1 grow previously). I’m using 3ml of both Sensi growth A + B, and 3ml of calmag per 1 gallon of water. I normally water every 1-2 days using a gallon between the three of them. Their under 24 hours of light, I’ve been bringing them outside during the day as I’ve only got about 200-300 true watts in the tent. Temps around here range from 75-90 so they’ve seen some drops. Rh both inside and outside are normally around 40-60 percent. Any ideas as to what’s causing the leaves to die from the bottom up, crumbling and turning brown? They started as small brown spots, so I assumed using RH water with those specific nutrients I’d run into a cal mag deficiency sooner rather than later. Any ideas??

Here's a deficiency chart I like https://www.rollitup.org/t/bright-agrotech-nutrient-deficiency-chart.1052024/
Might be in need of a good flush though.

Potassium, Read this: www.growweedeasy.com/cannabis-plant-problems/potassium-deficiency

I am using RO water, what’s the best additive? Someone mentioned flushing which confused me. Do I have too much nutes or too little?

VapidE said:

I am using RO water, what’s the best additive? Someone mentioned flushing which confused me. Do I have too much nutes or too little?

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Do you monitor the medium pH? Similar issues can occur with acidic medium.

I actually don’t, this is my third run ever, and I’ve never had a PH issue. However this is the first time I’m reusing soil. This soil was used in my last run and I got little to no fade when harvest time came so maybe there’s some build up??