Not really sure on that. I only have a soil Ph tester, and really went over our budget on the setup so I can get one for my h20 for a few weeks. I used a friends and tested store bought purified, and it was good, but I havent been able to test my run off.
I am using straight Ocean Forest soil, and the only additive I have used in the water is FloraNova grow, which I used 1/2 the recommended for the first time about a week ago.
The chart I was looking at showed it as a Mn issue..
Yesterday morning I switched the light, and watered with straight purified h20, this am those 3 were showing the spots, the other 5 look fine. Those 3 are also definitely all the same strain.
How long til you see signs of deficiencies? Would it be within 24 hours?
Now that you say that I'm going to go ahead and guess cal/mag lock out, and based on you saying straight fox farms for soil I'd guess acid lockout. Ya solutions/soil is too acidic, and your plant cant uptake mg/ca properly. This will start as minor burns, then will spread to dots, then it's burns and dots that dries out leaves.
I'd pick up an h2o pH meter, some ph meter calibration solution (important to keep your pH meter accurate, it will literally swing out of measurement in 2-3 weeks), and some Cal Mag. Totally worth it, you will see the vigor your plants have been hiding this whole time. I did my first grow without a pH meter, thinking, "Eh, I can do without it, I just spent all this $$ on soil and lights.. i'll buy it next grow". That grow without the pH meter suffered. They grew ok, scraggliy, and slow during veg. Then once they started blooming about 20 days in I started seeing leaf damage, I thought it was my light, but now I know it wasn't. By day 35 like 70% of my foliage was completely destroyed, only half way through flower. They didn't end up too awesome. It was weed, and a lot, but they were definitely missing out. Now I use like at LEAST 5-10mL Cal Mag
every watering. And my plants haven't showed signs of burning - so they are basically eating that shit up like candy. They love it.
http://www.icmag.com/ic/showthread.php?t=11688
Once you get your equipment ---- pH your water from 6.5-6.8, start acidic during veg, as the N gets taken up better, then gradually move to 6.7-6.8 for flower, which helps uptake phosphorous, which is necessary for later on in bloom moreso than N. I usually chill with the N feedings around day 25 flower. If you don't know, you control your h2o pH with pH up (blue), and pH down (orange). I also recommend once you get that, that you pick up some 10mL oral syringes at walgreens. They are commonly used for pets to swallow medicine, and also with humans, dull plastic syringe. It makes adding pH up/down really easy, as you can count droplets. The pH down is very very concentrated, 16 drops in my 8.2pH water and it's down to 6.7.
Hope that helps!
Will stick up some pics when they all come down!
