Question about aluminium foil.

I use alluminum tape for ducts its great for keeping heat and light in and was free for me seeing I had a roll at the house

The reflective duct tape is str8 but as for aluminum foil dnt do it it creates hot spots get sum mylar security blankets 2.50 4 82"*62"

If you have a limit of 5 bulbs then put 5 100 watt CFLs in there, you never said how many watts they bulbs could be only that you are limited to 5. Keep the plant trained so the canopy is short and even and keep the lights right over the plant. You will need to swap out to 2700-3500K bulbs for flowering

Go for the 250watt energy saving bulbs. I use these. Fell in love. They last a long time too

If u can't get Mylar or white paint. Check your local $1 store for silver Xmas paper. It reflects pretty well