[mushroombrew]

Just recently switched from T5's to 600MH. Seedlings, clones etc are loving it with lamp at 36"
Total lumens and lumen per watt are far higher with MH. But the switch was due to relamping costs. We were replacing T5's every 180 days @ $10 per bulb.
That's twice the cost of MH replacement.

Expected longer internodes with MH but the opposite is true. Very tight thick plants.

[Raho]

• Last time I started a bunch of seeds, I did it under a 600 MH and I got excellent results.
• If I were starting from scratch, I'd run 315 CMH. Phillips Agro 3100. Best spectrum on the market.
• T5HO's make a lot more heat than T8s.
• HPS puts out a lot of it's lumens in the IR range, operating basically as a heat lamp.

OP, please tell us about your environment.
Specifically, LxW dimensions, headroom and cooling capacity/air circulation.

Your current plan is to replace 110 watts of PLL with 150 watts of MH and you expect less heat . . .
The guy telling you to change your PLL tubes may have the best advice. Those bulbs can be had cheap.

[Manchineel]

I use T5s. I have 4 x 200w 4ft 4 tube fixtures in my nursery/veg/mother room all set up in strategic locations as I use shelving for seedlings and clones. I'm OS ATM so I can't post photos, but it works a charm. From 400w T5 (4100k blue light) veg they go under a 600 DE Gavita, which I crank up over the course of flowering to finish at 1150w by week ten.