Rust Spots?

[mortyb]

I have some Afghan in a 5 gallon with 1/3 super soil at the bottom (subcools recipe) & FFOF + FFLW on the top. My plant has been otherwise healthy so far, but is now starting to show some signs of rust.

I've been feeding it half tap water & half RO water (tap water here is too heavy in minerals).

I'm not sure if this is a Calcium deficiency, phosphorous deficiency or something else

 

[polishpollack]

hot soil mix. I wouldn't worry about the leaf damage unless it gets worse and spreads. look for bugs. it kind of looks like either mechanical or chemical action took place, rubbing the leaf on something or dropping a chemical on it perhaps. it's ugly but don't worry unless it gets worse.

 

[Renfro]

Has the look of a phosphorous deficiency. I would quantify my feed to make sure there is adequate phosphorous supplied.

 

[mortyb]

Has the look of a phosphorous deficiency. I would quantify my feed to make sure there is adequate phosphorous supplied.

I thought it might be a phosphorous deficiency. What's the best way to amend this organically without hurting the microbes? I've never tried an organic liquid nute like Earth Juice because I've been scared to kill the microbes. I'm worried if I just add some high phosphorous parent material & water it in, it would take a while for the microbes to break it down & become usable for the deficient plant

 

[Renfro]

I thought it might be a phosphorous deficiency. What's the best way to amend this organically without hurting the microbes? I've never tried an organic liquid nute like Earth Juice because I've been scared to kill the microbes. I'm worried if I just add some high phosphorous parent material & water it in, it would take a while for the microbes to break it down & become usable for the deficient plant

No clue, I am not an organic grower. I prefer chelated nutrients that have instant uptake.