Powdery mildew…increase temps/air circulation and drop humidity below 50% if possible. Buy an organic spray can use on vegs and eat same day.
Sounds like you getting screwed with the pool. I lived in an apartment when in college bunch of years ago and ran out of electric bill money (roommates and I only had money for pot and beer) and found out the entire parking lot lighting was on my unit.
Had landlord cut me a break on rent but if mine had never been turned off then never would have known.
Here check out my grow…costs me around $25.00 a month for more weed than I can smoke. Around 300-400 watts as varies as need less light when small and more light when large at finish.
Edit: also, looks like could use a feeding. Try some cal-mag. Healthy robust plant less susceptible to powdery mildew.