That’s not chlorosis by the way.
Make her up a nice banana peel mulch 
There is absolutely nothing wrong with osmocote and bagged potting soil. A hell of a lot more plants than weed are grown that way, by professional greenhouses and nurseries.
Check the runoff pH first and foremost.
Cursory glance diagnosis: it looks like the media got too dry for a period and burned. Does this describe what may have happened at all? You may have more than one problem, of course but that’s what the picture is telling me.
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I run 2 Mars Hydro ts 600s in my 2x3 I get decent results.
Fox Farm & Pro Mix. Do a transplant. Best recommendations.
Or start fresh.