yep agree mate use flouros for seedling, cheap as chips to get second hand, also throw in a few small fans, oen set to blow air at the 600w bulb, this will cool the lamp and push the heat away from the seedlings, then in case some heat is seeping down set your other small fan to blow down on the seedlings (slow setting) Other thing is that you need to have some outlet for the hot air. your fans will be pushing the heat around but you need it to escape somewhere so create some vents and keep em open while the heats so high This should drop your temp considerably with min cost although really you cant beat extraction fans to really suck all that heat out and blow it outside... but it comes down to cost and what you can afford to do, end of the day whatever you do that reduces the heat is a good start! Hope that helps Benny