the storm lamp "chimneys" are great for low wattage cooltubes but again they are too skinny for a 1kw bulb. there must be enough space between the bulb and tube for air to flow freely and bulb must not touch glass at all. i tried a "chimney" for a 400hps but it was too narrow so i got the bake-a-round. when i upgaded to the 1kw hps i had to buy a 6inch cooltube because there was not enough room in the bake-a-round for the cooltube to work properly. good luck building your cooltube,. remember 1000watts is alot of power when confined in a small space. you must use the correct equipment and wire everything correctly and neatly to lower risk of fire. i tried a diy cooltube for my 1kw bulb but decided to spend the 100bucks on a "real" cooltube. has anyone else here used a diy cooltube for a 1000watt bulb? i have seen alot of diy 400's and smaller but not any 600's or 1000's.