FYI, BL350 or BL368 bulbs would significantly reduce the required exposure times. I used these bulbs to build my exposure unit, their output peaks around 365nm.
The ones used for aquariums apparently provide peak output around 420nm. Check this thread http://www.apug.org/forums/forum42/9...rinting-2.html
My exposures are around 7 to 9 minutes with cyanotypes, both traditional and the new formula.