i have 48" of length under my 90g bottom drilled rr w/overflow to play with. i was feeling that the 30long tank was ideal for a sump/fuge but when i drew it out it only leaves me with 12" of space. i want to have a iwaki md 30 rt-115 external and that pump is 10 inches. not enough space.so i thought that going with a 29g gives me 18 inches of space. a tru-union for quick release would probably fit but does that leave me too cramped? i have it all drawn out and would love to show u guys as soon as i get accepted to the club(my pics will load!). Should i scrap the external for a drop in because of the space considerations? i understand that i should try to use external pumps when i can. u guys are gurus of reef keeping. thanks, brian in margate nj