Okay so around here I couldn’t find those long report cover bindings to make my dividers with so I went to Lowe’s to get some ideas and this is what I found. Its called PVC FRP Tileboard End Cap at Lowe’s (sold in 8 foot lengths) but I guess its also called PVC Profile:
The second one from the left is the one I am using in this project. Though I have also used a skinnier form of the middle one and it also worked fine. I found it at Lowe’s in the back near the door accessories. I am also using stiff plastic canvas:
as the actual divider but for something more heavy duty you could substitute it for plastic egg crate:
I siliconed the dividers in the my tank (in this instance I used a 10 gallon tank that I was planning on dividing 4 ways) in 5 inch intervals and let it cure for 48 hours (24 hours is sufficient though). This is the end result:
On the tank on the left I used the stuff in the first picture (the second from the left) and I found it to be easier to silicone in because the surface area was broader. In the tank on the right you can see where my silicone kinda went all over the place using the skinnier version of the stuff in the middle of the first pic.
Now I hope I haven’t been too confusing but you can PM me with any questions you may have.