Help with spots first time grow

On day 17 I first seen these spots on a few leafs. Based on all the research that I did to find out what the problem I decided to do nothing and see what happens. Everything went well based on that decision. Until now, Day 48. When I search "spots" on this forum I haven't came across many pictures that look like what I have. A lot of post that I have read always throw out "Spider Mites" when it comes to spots. I don't have a loop to see, but I don't think that is the case. Can someone help me with this?

Strain is an Autoflower
5 gallon bucket (DWC)
Air stone w/ 950GPH Pump (Plenty)
Advanced Nutrients PH Perfect (44 ml of each)
BigBud 22 ml
Hydroguard 6ml
Light at 16"
Room Temp 72 - 76
Humidity 45 - 50
PH? I don't measure based on what I have read about AN products.
Bucket change every Saturday.

I have also read that Auto's can consume large amounts of cal/mag. I don't know how much truth there is to that.

What king of water you using?
Ec and ppms?
Ph is important if soil isnt ammended properly, which can effect nutrient uptake. Doesnt hurt to check it? See if its in range.

I'm using tap water that is approx 150ppm

lime73 said:

What king of water you using?
Ec and ppms?
Ph is important if soil isnt ammended properly, which can effect nutrient uptake. Doesnt hurt to check it? See if its in range.

Click to expand...

I'm doing Hydro by the way.
Lights came on and I checked the PPM and PH.

PH 6.04
PPM 1140 - tap at 150 = 990ppm
Do I need some cal/mag?