I'm using the Fluval foam block designed for the 110 model. Nothing sandwiched beneath it or between it; it's the bottom layer of my media stack. On top of it is the floss, Purigen and BioMax sacks.It doesn't matter how you want them to work as long as they can serve the purpose for which they were put there. They are designed to prevent the media from lifting out of the filter. The basket and those hooks help to prevent that. The proper size foam block should fit under the "hooks." If you have something between two layers of foam or if you use a custom foam block that is taller, then those hooks should hold down the foam by sticking into the ends of the block. Like I said, any way they can serve to hold down the foam is fine.
I don't understand why it's to be accepted that "any way they can serve to hold down the foam is fine" -- there MUST be a proper way to use these things because I can tell that things change as I position the media certain ways -- for instance, when I use those hooks to hold the block down, pushing the four edges of the foam underneath the teeth, it causes the center of the block to "bow" and deform, making the center bulge up and therefore no longer a "perfectly flat" surface for the next layer of media (in my case, the floss) to sit on.
What is the correct way to use those media basket "teeth" or "hooks"?
Not sure why I have to keep stating this, but the media has NOT been neglected in this case -- it's regularly rinsed and is NOT clogged. Something else is causing the basket to rise and it has to do with the way these hooks are catching or the way the foam block on the bottom is being loaded...However, failure to rinse out the media regularly will results in disasters that come in stages. First the basket and media will lift up some. Water will be flowing around and likely some is spilling out from the intake area into the tank. This means water is going unfiltered. Next, the clogging will get severe enough that the water will be able to overflow the top edge of the filter. If one has failed to install the filter so that it tilts towards the tank, you will be pumping water onto the floor.
This will continue until the water line in the tank goes down to the intake end of the uplift tube. At this point the filter is still churning the same water and heating it. Given some time it will heat the water to where it is killing the bacteria in the media. I think this is as bad as things get. But I have never seen one run until the water completely evaporated out of the filter and the impeller kept spinning.
The moral of the story is:
When you notice the flow of water coming out of the filter has slowed, rinse out the media!