Setting up a Sand Filter for 240g Freshwater (question about Nitrate Reduction)

So I have a 240g that I'm setting up with a wet/dry 70g sump. I have more pump than I know what to do with right now (Laguna Max-flow 4280) and so I was thinking about building a fluidized sand filter out of some clear 3" or 4" PVC that takes some output and feeds it back into the sump.

My question is: I would really like to explore the possibility of creating an anaerobic area towards the top of sand column to reduce nitrates, with the assumption that the taller the filter, the more likely I can establish an area in the filter that is devoid of O2, that may support this.

So anyone have any ideas concerning ideal or min height and what flow rate (numerical or visual) I should be shooting for? I was also thinking about how to outgas the return water since it would have the potential to contain nitrogen gas(someone was saying H2SO4 was concern), among other possible nasty stuff. (Still reading up on the chemistry, as I'm an electrical engineer that sometimes moonlights as a Chemie at work). As far as the H2SO4 protection goes, maybe run the water through a medium that would buffer it (calcium containing media?). H2SO4 scares me the most, as even 1ml will dramatically drop PH unless your solution is very well buffered.

See for some explanation of the process:
http://dwb4.unl.edu/Chem/CHEM869P/C...c.edu/microtextbook/metabolism/RespAnaer.html

Anyhow, I have seen a few people posting about them and while I don't want to just go pure Sand w/o a sump, I really like the idea of having the possibility of having a method to control nitrates... outside of putting some plants in my sump.

Idea for the Sand Filter:
http://www.monsterfishkeepers.com/forums/showthread.php?208356-My-DIY-bio-tube-filter...thing

Basically, building this w/ clear PVC and maybe some type of tower for out-gassing and for buffering?

http://www.americanaquariumproducts.com/FluidizedSandFilter.html

A commercial model.

bump....

No one has any experience in Nitrate reduction or FSBs?

I was also thinking about pothos for my sump for nitrate reduction (bought a shop light just for this purpose) and I also agree about the need for water changes, outside of using them for nitrate reduction....

I was thinking 4" and a similiar height of 4' for the fluidized filter.

Do you think maybe I could pull it off with more sand in the filter (your pics make it seem like you don't have that much aragonite in there?) and a higher pressure / lower flowrate with some course sand that might allow for the surface of the sand to not really be disturbed by the flow rate?

I guess I will just have to pull out the CC and get some clear PVC and start tinkering.... thanks for the info and experience with your setup