The reason for the dividers is for bubbles and in the case of a refugium, to keep sand and plants out of the pumps. My sump does not have "chambers". I have a 75 gal
stock tank with a 12 gal
rubbermaid tub inside the 75 gal
. I have a hole drilled in the smaller tub so it will drain into the stock tank. I use rock to act as my bubble trap. My sump is in the basement so I see a lot of bubbles. The rock keeps it from reaching the return pump. I have a skimmer in the sump and a pump that supplies the frag
I my first sump, I used a 20 gal
glass tank. I used small plastic container that wedged in the tank to act as a bubble trap. The skimmer was on one side and the return pump was on the other side of the "bubble trap". If you have room, set the refugium up in a different container. Raise it up so that it can gravity drain back into the sump and use a PH
to supply water to it.
You could get some acrylic sheets at HD
to add walls as well. For a bubble trap, they don't necessarily have to be siliconed but you need to keep sand away from your pumps.
More than one way to accomplish what you want.