Help me decide on a new tank size

[tang daddy]

50g breeder is a good size 36x18x18 although you could probally add 2 more t5 to the new tank, just keep the old light and add 2 more retrofits....

under t5 the sps can grow pretty good up to 10in depending on wattage, I believe your light fixture is at least 39w per bulb??

then you can have softies at the bottom. I did this awhile back but found it to be not enough space so I upgraded to a comfty 75g!