Brown spots on my marijuana leaves

A question from a fellow grower:

The og Kush plants are doing pretty good. But on the larger one, #1, I see more spots. I’ve changed the nutrient water every 7 days so far with a ph of 6.0-1. Water starts out 16 ppm with nutrients 181. They popped the Rockwood on 3/25.

Pictures would be a big help to analyze this.

I don’t understand your nutrient strength. You meniton ppm, but 181 ppm would not hurt anything; In fact most water is above that.

Did you mean EC? 1.81 would be really strong for a plant less than one month old.

Please clarify.

I think he means the water he starts out with is not 0.0ppm and after mixing his nutrients it is under 200ppm

So after you mix nutrients every 7 days change the water because the Ph level rises I think that might be my problem I don’t change my water often

Yes, changing water often will help keep things from becoming too imbalanced. Not just the ph level, but some nutrients may be used up sooner than others and if the ph gets too out of whack some nutrients will become unavailable or “locked out”.

True. When PH is too far off, certain minerals may be locked out.

I always try to top off the reservoir through the week. This allows me to add ph’d water which pretty much stabilizes the PH for a day or 2. I also find that my ph does not waiver as much, as long as I do not go past 2 days before topping off with ph’d water.

Another important thing to know here is: You can only top off with ph’d water until you have used as much as the reservoir holds. i.e. If you use a 5 gallon bubbler; Then you cannot add more than 4 gallons of ph’d top off water before adding a fresh batch of ph’d nutrient solution.