Originally Posted by
jeep
Nice job on the 155!!! I think you are definitely on the right track as far as overall size of tank to number of discus. A 75 is just too small for 12 adult discus. I'm not sure if driftwood or plants will decrease aggression, but I don't think it would. Maybe the increased tank size will help with that. The aggression could be territorial or jealousy. I have 7 adults in a 60g tank and although there's no real aggression, they all use up about 1 foot of space trying to get the attention of a female wanting to spawn, lol...
I like the bulkhead option. Easy to install and remove if you decide later on...