brown spots on leaves - what is it

I have these rust spots on my lower leaves, the plants are mostly healthy but some leaves look bad. The top of the leaves has rust spots and on the bottom there is brown stuff. Here is a picture of the backside of 2 leaves that look bad.

I am growing in coco with canna nutes. H2O2 is the only additive. I sometimes spray safer sulfur fungicide and pyrenthium insecticide. The spots may be from the stuff I spray, but I am afraid they are some insect eggs. Anybody seen this sort of thing before?

also I have an ionic breeze which produces ozone. Anyone seen this? Ideas?

could be aphids...do you see any white bugs flying around? are there eggs on the underside of the leafs...check most of the leafs on the bottom nodes of your plant..i've had an ahpid problem..they suck the sap from your leafs causing them to die! if no bugs...is the spray your using organic?

could need some magnesium (epsom salts)

it may be ozone burn but if its on lower leaves and its progressing up it mean u have a K-P def. over all i would feed them