When to switch to hps

if tall enough? now is good

 

i keep my MH bulb on until the stretch is over then switch to HPS
it does control the stretch from getting crazy IMO
during stretch i also continue to feed the low ppm as in veg
when they stop the stretch i start scratching in top dressing, tomato tone is my favorite

 

this

 

try it, it helps mine slow down, im growing in a 2 x 4 by 5 tall tent, so i dont have room to let them get leggy haahah, when i use coco i even feed veg nutes the first two weeks along with the MH bulb .
aint no growing in a tent this summer , dang temps been triple digit for months it is 105 and 111 in direct sun
when i do run , i run 6 3gal pots and when them plants get 15in max tall flower time , they finish out right about 6inch under the lights a top of tent

 

the roads are melting here hahahah
i quit growing in summer months, ive tried the led thing also it was worse IMO with my cool tube and hid lighting works best for me
i do use them led light for starting my garden veggies, have onions under them as we speek
onions from seeds take decades it seems

 

if you bought 2 cool tubes and ran a exhaust out the room it would cool your room by half , them wing fixtures put out tremendous heat, i have one myself used on one grow about 5 yrs back, to hot for my climate

 

was trying to send you a link but wouldnt work ,amazon has that cool tube for 24 bucks

 

I spent years with a setup similar to your, if you can, you want the hoods in parlel and a large carbon filter/fan(8") in the between the bulbs(level with the bulbs) this will pull the heat straight out of the room.
Next you want a large intake fan( 5" or 6")(one size smaller than the extraction fan)
You want the intake air flow behind a large floor fan, so you have a good amount of cool air between the canopy and the bulbs, I would also look at different reflectors like "adjust a wing", they cover a large canopy and reduce the amont of heat on the canopy.
Imo a 600w hps can be very effective.