Filter return spray bar under reef?

Hi all
I have a 150 gal. I set it up 15 years ago. Recently the bottom seal sprung
a leak and I had to take it all down for repair. While it is down I decided
to upgrade all the little things I wished I had done in the first place. One
thing that was mentioned to me a few years ago by another reef tank owner,
and I am thinking about doing, is to make the return water from my wet/dry
filter spray out under the reef. I thought about doing this by placing an
under-gravel filter grate down under the coral sand and live rock. I would
put my spray bar that used to be over the top of the tank under the grate
and it would pressurize the space under the reef and the gravel. The
intended purpose would be to keep detritus and guk from building up under
the reef where it is very difficult to get to during regular cleaning. Every
time I have taken down my tank for rearrangement or repair it is incredible
how much build up there is even after frequent gravel vacuuming and the reef
has only been about 4 years old at the oldest any time I had occasion to
tear it down or rearrange it.

The concerns I have about this is possibly creating a situation that would
expose the live rock and its inhabitants to too much oxygen, or some other
consequence that I am unaware of. I have considered the loss of anaerobic
activity in the live rock but I think that is mostly in the cavities in the
rock its self and not so much under the gravel. I am also adding a coil
denitrator to the filter system and even if I lost some anaerobic activity
in the rock the reduction of decaying proteins and detritus under the reef
and gravel would seem to be a fair trade off. The other possibility is the
reduction of aeration of the water by loosing the "spray" on the top, but
all the turbulence in a trickle system cycling 500 gallons per hour, and
using a down-draft protein skimmer at about 250 gph. I think there is plenty
of contact between air and water. The over head spray bar is probably
redundant in that capacity anyway.

What do you think? It sounds good but you know how that goes, years have
taught me to be cautious.

Has any one tried this, or heard of any one trying this?

Got any other concerns than the oxygen?

I welcome any comments

Thanks
Greg