I have a question about heat.

What light would make more heat a 400 watt 4ft 8 bulb t5 panel or the black dog xlu 750 watt led.i own the t5 and it is a little hot for my space but I can get a deal on the blackdog 750 if it would run cooler it would be a major upgrade for the flowering chamber. Thanks

That's a pretty old LED system. I'm not familiar with them directly, but judging from their specs and the absolutely massive sinks and fans they are using. I'd say that xlu 750 puts of a good amount of heat. If you got one for a couple hundred bucks, great. I wouldn't pay more than that. Any details on your grow space?

2'x4'x 30 inches tall for the flower chamber.