I know this is a little late but you could also get some strips of glass cut for you, about 1/2" wide x 1" short of the inside height of the tank. you will need a total of 12 strips. Use 1/4" thick glass.
attached the strips to the glass two at a time next to each other flat against the tanks sides with just enough room for the acrylic sheet slide in between them.
do that on both sides for each partition.
you only have to use silicone at the top near the rim and then at the bottom below the gravel line to hide it.
you will also have to cut notches in the top frame/rim most likely as well, but just the lip on the inside, not the entire frame.
then you can slide the dividers in and out as desired for different situations.
or you could swap them out for dark ones if you need to put males in there..