Sump - adjustable wall

We have an Aqueon three-chamber sump that we're struggling to understand (we're going to finish filling the display tank tomorrow so that it will overflow and start to fill the sump, so we want to be sure we "get" it before we jump in). The sump has an adjustable wall between the first chamber and the center (refugium) chamber. The instructional videos we have seen smugly say to "lift the wall to the top," but it says nothing about how it is supposed to STAY there. There are little ledges on the inside corners of the MIDDLE chamber, but the adjustable wall lives inside the FIRST chamber, so it can't rest on those ledges. Is it simply the water pressure that holds that wall up? Will we have to hold it up with our hands while the sump fills up? Anyone have any experience with/advice about this unit?

Nope -- no thumb screws or anything else.

Does this sound to anyone else like a disaster waiting to happen? Manufacturers make plenty of mistakes. I've seen, and fixed, a lot of those design flaws.

A wall of Chaetomorpha works awesome as a bubble trap and a few small live rocks hold it in place. That's why I disregard baffles and use containers, pedestals and hangers(zip ties) to hold things in or up. The plastic box screens used for swamp cooler pumps are awesome for blocking algae from the pump intake and flipped upside down, work well as a pedestal.

dougandtito wrote: First: This afternoon, while getting our latest dose of water for our tank (which filled it enough to start filling our sump), we were told by our fish store guy that for our refugium we want to lay down a bed of something called Mineral Mud. I have learned and been reminded to take everything our LFS (just learned that acronym! :)) tells us with a grain of salt, so I listened with skepticism, but I do understand some logic in the idea that we'll need iron and other minerals for our refugium plant to thrive. So although we decided NOT to get the Mineral Mud, I wanted to ask in this forum whether there is any truth to the claim that we need something like that. Second: Our sump has three chambers, with the refugium in the center chamber and a half-wall divided the refugium from the third chamber (where our return pump is housed). How full do we want that sump to be? When the pump is running, should the water in the refugium chamber just reach the top of that half-wall, or would we for some reason want the water to go higher than that? I'm 95% sure that we don't want the refugium water spilling over into the third chamber, and that we want our sump water level to be just below that half-wall when the pump is running, but I'm new enough that I don't trust my hunches and want y'all's advice. Thanks!

(OK, actually, slow computer, gotta run some errands, so that new-thank thread will show up later tonight probably.)