Im thinking about setting up a cacti room. (i sell cuttings on ebay) etc

the area is 115cm x 2020 by 85cm high. That height is fine for my cacti it takes them two years to grow an inch.but they get a lot thicker under HIDS

Seeing as its so low in heighti will have to use a good vent system so have been thinking using 250wattMH on one side while 4oow aircooled on the other.accousting insulated ducting going through both.

The accoustic ducting had a hole in the ground to go out into an area (box)the hot air will cool quickly.
I cut two large 150mm holes in the box and am thinking of spryaing water saving crystals all over the rocky floor in there, 1litre water every week then hot air comes through and cools before it exits other hole.

Anyway what do you think of insulating grow room walls for sound..i need it to be very quite. i saw some accoustic insulation for sale and thought id line it with that and put poly on top.
Even though cactus is legal i want to be stealth about it and quiet as possible.
I already have accoustic ducting and the 150mm fan will have acoustics insulation wrapped around it.