PH is 5.5. 700 ppm of JR Peters 16-4-17 Oasis and 1 1/2 ounces (diluted in 40 gallons) Epson salts. Room temperature around 80° with 40% humidity. 1000 W equivalent LED suspended approximately 3 feet over 6 plants. Plants are in a 5 x 5 grow tent. Using a super closet 6 bubble bucket hydroponic system with a 25 gallon reservoir outside of tent. At 1st this looks to me like nitrogen deficiency as it's yellowing on the lower leaves but I read online that in nitrogen deficiency the leaves should be yellow and soft. These are yellow and brittle. Also, I just can't believe it's nitrogen deficiency as the PPM of 600 that I'm using was recommended by the nutrient manufacturer. I change the nutrients out once per week. I'm going to do that today and bump up the nutrient level to 800 ppm but I don't hold a lot of hope that this will fix the issue.
Looks like a root problem, root rot or PH fluctuations from the droopiness/wilting, the dying of the lowest leaves and peeling appearance on the leaves above. Doubt it's nitro def because the leaves don't wilt like that and I think the yellowing spreads more evenly over the leaf. Also top leaves look dark suggesting plenty of nitro.
1 1/2 ounces of epsom? Thats quite a lot no? Im not a hydro guy but mag excess will increase uptake of Nitrogen and fuck calcium and potash by locking it out. Just my two cents.
Excess mag can be captured by using gypsum (calcium sulfate) as a topdress in soil. The sulfates drops the weaker calcium bond for favor of magnesium which creates magnesium sulfate (epsom salt) and is then a flushable salt. In a hydro system? No clue but someone will. I know gypsum wont work though.
The one and a half ounces of Epson salts was recommended by the manufacturer. They have a good product but it lacks sulfur because the addition of sulfur in their product would turn components of their product to gypsum. They recommended one and a half ounces deluded into 40 gallons. I came to a similar conclusion that it could be a root condition. Probably my reservoir water is too warm. I know this can cause problems with oxygen uptake. I'm going to add a small dilution of hydrogen peroxide to my reservoir tank. My understanding is that this can help clean up problems and add extra oxygen so the temperature of your reservoir water is not as critical.
I'm not sure what JR Peters Oasis is like but the phosphorous levels seem a little low at 4 might need some additive to boost P. With the Epsom salts.. I suppose that's approx 1gram/ml per gallon which doesn't seem too much to me, but they do seem really hard to dissolve and I'm not sure if any undissolved salts could have caused an imbalance when mixed in with the nutrients. I would probably stick with using just the JR peters at qtr or half strength and PH the water, then only add epsom salts if it starts showing sulfur/mag def.
Is your ppm dropping? if not I wouldn't raise your ppm.my ppm is 500 right now. This is the .5 scale. What Version scale is your meter ? What's your water temp? How much air are you putting in each bucket? And 5.5 is on the low end 5.8-6.0 I find to be good. I am on my first grow and am learning but so far so good.