Ive got a DWC system going with 3 kinds of Autoflower strains in it. im going on my 4th week since germ. Everything seemed to be going good untill the bottom set of leafs on one of them started to get a couple of spots on them... now its gotta a little bit worse so i thought i get some opinions on it.
DWC System 20 gallon bucket (15 gallons in it)
2 18inch airstones powered by a elite802 airpump
CNS17 Grow and Bloom Nutrients
400w HPS light
My PPM was at 190 when the problem started. Im kinda new to the autoflower strains so im not exactly sure on what PPM is recommended. My Ph went up a little in the last couple of days so been adding a little of Ph down to get it back to normal (5.5 - 6.0 is what i heard was the best for them ).
The top leaves look fine and dont have any spots on them so im kinda confused on the whole situation. Any help would be awesome.