Thread is a little old, but I will throw this out there ...
I use a 20L that I had drilled for a 1" bulkhead. It is part of my main system. I use a 2x55 PC
fixture that I made with 2 $8 ballast from HD and 2 55 watt bulbs. I have seen PC
bulbs as cheap as $10 if you catch it at the right time. The same ballast will run a 2x32 set up which would be sufficient for some softies.
*180 gal Display, 100 gal basement sump, 33 gal refugium, 3x250 MH, 2x160 VHO actinics, zoos, some softies, LPS & lots of acros and other SPS.
*100 gal prop tank plumbed into main system w/ 2x96 PC lights and 1x150 MH,