So below is the design I use, you see the water falls vertically through the media through a spraybar, into one or two layers of fine filtration media (I don't use Poret foam, only because it is a bit expensive, so I use densified polyester matting, Nufoam Polyfil, from Walmart). The spraybar dispereses the water lengthwise over the media, soaking the latter and then, it drips down through the biomedia (the biomedia I use if the one that has best worked for me throughout the years, which is preferebaly Hydroton Clay Pellets, if not, polystyrene pellets, balls or peanuts or nylon pot scrubs). All the this bio and mechanical media can weigh quite a bit, in the case of clay balls, so you need a firm support that allows quick and complete drainage, and therefor we have a cheap plastic eggcrate wrapped in a plastic mesh screen so the biomedia does not fall through the eggcrate holes. You can have this bottom support plate done in acrylic, or any other material which is practical...I'm just telling you my cheap solution. Then finally three clay bricks keep everything off the glass bottom, some 6 inches above. Water level is maintained via a ball valve, just before the spray bar and we have a safety check valve after the pump.
I actually have my UV running separately at present, as a separate unit.
The cartridge setup you show, supposing we are talking of commercial 10 inch housings (under the sink type) are not designed for this application and I don't think the water flow through would be sufficient... it depends on the size of your tank and pump*. Then you have the Lifegard modules, but I don't think that was you meant to illustrate.
In anyway, water level must be below the egg crate line. You should see the water dripping or raining from the entire bottom of the layered media pack .
All you need to do now and then is remove the top mechanical layers and ring them out or replace them.
** My large tank needs at least a 1200gph pump and what I have drives almost 2500gph... you can't try to push that much water through a 10" housing array without the pump suffering.
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