KayakJimW: Please any holes you put into the plan will help me to figure out possible solutions and area's that might not work. The bubblewand Might be a good idea but here is my concern with it. and maybe I may be off kilter. but Wouldn't adding the bubbles creat surface agitation and a loss of Co2. Now granite my tank and sump will be covered so I shouldn't have to worry about evaperation as i have been when it was open topped. but I like the idea of the bubble wand but I be a little hesitent on lossing any Co2. as I am not going to be doing injection. I do know however it can create a natural equilibrium, but in a closed system just how effective will it be?
Now as far as the chamber it will be in, I think it probably would be best to be in the closest chamber. However If it is going to be in the chamber closer to the sump it might not collect as much detritus. but my sumps have always seem to have detritus around the pump area regardless of how much floss i have in the tank or how often i clean. I think after a while no matter how much you clean your floss, it will still make its way to the pump area. (i even found a baby cory in my pump chamber of my 20g that apperently the egg had made it through my filter floss, through the lava rock bio media in to my pump chamber and I didn't realize I had a baby fish in there until I tore down the tank a few months later and found a small catfish in their.) Plus another thing is if it is in the rear chamber. if by chance any isopods or anything that might grow in this setup will make its way easier to the pump and to the display to feed the fish. I do consider running a ATS though probably a small screen size just to keep algae out of the display. (hence the isopods or other micro food) I just think the rear chamber also will keep the substrate from clogging as fast as well because now the small ammount of detritus will be broke down faster by the plants, and Bacteria. of course I may be wrong. I think before i set it up I really need to debate the pro's and cons of what chamber I should try it in.
Latent: In the reef community they do plenum substrates a lot and they use a fiberglass mesh screen to keep the sand particles suspended. I don't think play sand would work as it is to small a grain size. pool filter sand could potentially work if the grain size is large enough. I know that Black Diamond blasting sand 20/40 and or the one higher up will work. along the lines of safe T sorb gravel. and or any other plant based gravel.
Something else I have been thinking about. instead of making a traditional ATS , whit if I used one of the chambers to grow algae. use the screen like you would for a ATS but have it in the chamber submerged and let the light flood that one chamber so algae will grow in the chamber like Cheato does. In theory my goal is to have the algae grow in my sump and not in my display also the Algae would consume what ever nutrients are in the water column, while my root feeders will consume whats in the substrate. of course this is just theory and some help in this area and maybe some tweeking could be advised.
Your post sound like you have been reading about the use of sumps on SW reef systems, and trying to apply this directly to a FW planted system. Because the goals are reached differently what you do in one is often not want you want to do in the other.
On plenum sandbeds. Even in SW these are rather out now. Mostly because they don't really offer much improvement over a plain sandbed. Like a lot of other things in the aquarium hobby, this was tried and long term didn't work out. At least it wasn't hurting anything, so if you had a tank using it, you didn't need to be in a rush to remove it.
Running a plenum so water flows through it in effect turns it into an under gravel filter. These have more or less been banished from FW planted tanks because these systems work better with out them. You would also turn this area into a massive dirt trap. You usually don't want that either, although it's not going to hurt anything. Consider the dirt can stay very nicely in the display tank until you siphon it out, and it's a lot harder to siphon out a sump.
ATS (Algae Turf Scrubbers) can work great in a SW reef system. They can be very good at removing nitrates and phosphates. It's done in a reef system because there are few plants in these systems. In a FW planted system, you typically have plants all over the place, so adding an ATS usually has no advantage, and it's one more thing you need to clean. The one exception I can think of would be if you want to set up the display tank with only rocks and driftwood and no plants. There an ATS could do wonders keeping algae in the display tank down.
A chamber to grow algae is about the same as an ATS, except that it's much less efficient. In a SW reef system this is done so you have a place to grow macro algae. This is not needed in a planted tank because you have all the plants, but you could do it. One area where this might work well is if you want a shrimp tank that's part of the total system. You also might be better off growing more plants, rather than algae.
One thing to keep in mind is that if algae can grow in an ATS or an algae chanber, it can usually grow very nicely in the main display tank.
A bubble wand is one of those things that won't hurt but also will not help much with a sump. This is because the water going out the overflow from the display tank really gets "bounced around" and this will do great gas exchange all by itself. CO2 out O2 in. Usually this is about as effective as you can get all by itself.
As you can see you really don't need to much in a sump that is on a FW planted system. You usually would want some kind of mechanical filtration, and a place to add chenical filtration such as Purigen or carbon. You could also place biomedia there, but few FW planted tanks need this, but it will not hurt.
Lastly, you might want to consider CO2 injection. It will do wonders for your plants, and overcomes any loss from using a sump.