Attic DWC grow with 600watt, advice?

I'm going to be putting this 600watt HPS up in my attic next week. I'm building a 6 plant DWC setup right now. I have a few questions before i get everything started.
Since it's gong to be in the attic it's going to hot as hell up there in the next few months, so what are some efficient ways of cooling the surrounding area?

When i start the babies in the rockwool and put them in the netpots, should i water them like a normal plant until i see root growth?

And i was also wondering about when the roots start to get longer, should i be lowering the water level in the res. so that i wont end up with root rott?

are you using a tote for your res, any airstones or bubblers? is this an attic in the house?

Im using a 45 gallon tote for 6 plants. im using two air stones and two bubblers so that there's one one of each, on each side. Yea it's my attic lol. My buddy uses a 1000watt up in his attic and when it's fall/winter time his harvests are amazing, but when summer comes around and the heat gets back up, all of his plants turn out extremely heat stressed. I'm worried about ventilation as well. It's a decent size attic but the air is hot and still up there. I'm not sure that i want to run ventilation to the attic vents either since a ton of heat pouring out the side of my house would be kind of interesting to eyes in the sky haha.

Hey there. I have an attic setup and temperature is my only real issue. Although I have the space fully insulated with 25mm polystyrene, temperatures in summer are a major problem, even though I pull a ton of cool air in from the cold side of the house. I wont try getting thru another summer without AC.

As a guide, my 600w raises temperatures in my space by 7'c on average.

Now that winter is starting I have the opposite problem, with the space only staying about 1c warmer than the outside temp, when the lights are off. I have just had several 9c nights, so this is a bit of a concern. One solution is to have the lights on over the coldest part of the night, but yeah, I do wonder about visible heat escape. As I never hear choppers overhead after 10pm, I tend to switch on around then.

To be honest... I don't think you will have much luck unless you too address these issues. An AC is the obvious answer but there is the initial cost and that of running it.

Good luck!

When I used to live at my parents house, the basement didnt have central AC so i had this window unit sort of thing, it just had a hose that would to a small crack left open by the window, i might see if i can find one of those. Does anyone know about the water levels as the roots grow in the DWC?