Thank you Niceopt. Appreciate your detailed comment.
So I've done some thinking and experimenting with the a\c since I've read your post.
Also changed the MH with HPS and introduced Big Bud yesterday. I used A\C water @ 0.1 ec and upped the nutes a bit - 1ml p\l Canna A+B, 1ml p\l Cal-Mag, 0.5ml p\l Big Bud. EC remains 0.95 as of RO water and I upped the nutes by quite a bit so I'm happy with that. plants look happy as well. runoff was 0.95 ec and 6.6 ph. maybe It's a nute lockout? I feed 2 Liters x 5 plants and I get 3-4 Liters runoff.. quite alot.. maybe they just don't eat?
Also I found that if I duct half of the shutters of the portable ac into the tent and other half to cool the room, it can work for hours without getting hot and smelling from gas and keep the temps at no more than 26c @ 60cm away from canopy. we will cut down as much as we can with the main ac but with it on I could probably lower the lights to even 40cm away for some good hours though the day.
Finally, I decided I'll just go with 18\6 when the lights off time is when I go to sleep til I wake up + 1 hour of only having main ac on. It's simply because the portable's noise is unbearable and I can't sleep with it.
Rest of the time it will work with either portable ac alone or together with the main unit as explained.. portable draws only 700w from the wall (I have a counter so I can pay the room's electricity in separate, living with roommates. lol) so It's nothing in comparison to losing a grow for heat.
In regards of feeding.. it's the second feed in two days and they definitely seem to love the faster pace. they are green and a lot of new shoots are coming out. I might be imagining but it looks like 24 hours after giving big bud shoots were really starting to form a crown-like shape.. I always believe if I see a fast reaction from a change in diet then it means I did it at the right time. Hope I'm right, even though I feel like I could have started feeding Big bud a week earlier..
And about the QB's brother, what are the size usually of these boards?
I found a 100w Horticulture Group QB that says to light a flowering area of 60x60. two of these would cost $450 which I could probably afford in a month or two..
But then I saw a 250w QB same horticulture group for the same $450 but it says to light a 120x60 flowering area... I guess because it's long and not square.. So question is would a 100w x 2 QB's be able to replace my 600w HPS in both yield and quality? Heat control is just the extra...
So um.. really hope I nail this 60g per plant target. cause it seems like there won't be another run for safety reasons and I smoke a lot
Cheers and thank you bro