I was in WalMart today getting some replacement bulbs - I use 4 2'
flourescent bulbs for one set of plants - when I noticed lumen output
varied widely between bulbs. Aquarium/Plant bulbs had 750, Home and
Bath bulbs had 1250. And for the same space, I could get 3 or 4 times
as many lumens with compact flourescents - the circular halo-looking
things. All at 20 W apiece.

More lumens means more light, right? Is spectrum a factor, or for the
same price why wouldn't I just go for the highest lumen count for the
space? What am I missing?