Rust Spots on Cannabis Leaves



Can someone tell me why I have rust spots on the first and second sets of leaves. This is my second grow with no issues on the first grow. I am using RO water and I added a 1/2 dose of Cal/Mag on the last water change and this weeks water change. Please advise.

4 Likes

You mean you added extra Cal/mag to the water? If so why bottle 5 is cal/mag

2 Likes

Do you have a Ph meter I would start by checking that… If you don’t have one I would do a health check on your Ph probe just want to confirm your Ph is inline

3 Likes

I recalibrated the ph probe before starting this grow. I am going to check to see if any of the nutrient lines are kinked, I noticed the nutrient lines were very tight and I couldn’t pull on them. Thanks for the advice.

2 Likes

I purchased a Blue Labs ph/ec combo meter this week. The ph reading was 5.9 to 6.0. The tds reading was 1120 ppm. The leaves continue to get spots on them, seems they are starting out as very faded white spots. Any idea what is happening? Thanks

2 Likes

Oh, forgot to mention the water temperature in my grobo is 73 degrees

2 Likes

You Ph and ppm sounds fine…

No problems with your airstone?

When you do a drain / fill your bottle 3,4,5 are dosing ?

No little bugs under your leafs?

It does look like Cal Def but if bottle 5 is dosing I would think you shouldn’t be needed any extra Cal

2 Likes

During your other grow with no problems, were you also adding things yourself or just letting Grobo do it?

We are not adding anything as we really don’t know, that is why we bought a Grobo, to let it do everything.

3 Likes

I replaced the air stone with a new air stone when starting this grow. I haven’t noticed any pest on the underside of the leaves, I will check it out with a jewelers loop to take a closer look. Bottles 3,4, & 5 are all being dispensed, I started this new grow with new nutrient bottles. Other than the spots on the leaves, the plant looks healthy and is growing nicely. I’m not sure what else it could be. Thanks for your help.

2 Likes

The only thing I added on my first grow was Hydroguard. I did add Advanced Nutrients Big Bud and Overdrive in the flowering stage.

2 Likes

If your water temp is 73 I would continue to use hydro guard this grow also.

Maybe open a ticket with Grobo support maybe they can see something I’m missing

2 Likes