is this heat realated?

i am not to sure, you have to post some environmental factors in order for us to try to properly diagnosis. i know one thing, it's definitely a potassium issue and possibly something else if the problem persist.

I'm using vic's soil mix as my grow medium, under cfl lighting, water only.

The heat got to a point where I was seeing mid 90's inside my cab. I have since added a small modified air conditioner to my box. I only run in on hotter day and it keeps things under 80 degrees. My cab is in a attic type of location to keep it as undercover as possible.

I can see it as heat problem watch it keep it cool i think something else also but cpuld be wrong

yeah, it's definitely heat/environmental related. anything 85 and above, expect to see all kinds of problems.

Make a co2 maker i would and did on my last grow my temps were 95-85. It workes well co2 yeast and suger all u need after awil it starts smellin like beer id change it every week