I had no plan either !
Now I have 42 breeding grow out tanks besides my 180 display tank.
The 180 has a sump running it and when I moved the sump to the basement[and drilled a hole in my living room floor for it ] that opened up the basement as future fish room [or 2..]
I ran the 6a for at least upto 20 tanks without problem.
Sponges work on all size fish tanks while that can not be said for all other filters.
I haven't changed what I breed ,I am still having fun with my GBR and EBR ,but I just added a tank here and added a tank there instead of changing when I found new interest...
Trying to find room for more as these fish just breed too easy for me !