Beach vrs. Tank sand test

I ran a test with the fresh beach sand (dug out of the surf) and my tank
sand. I setup two small containers and added shrimp meat to both and
put them aside for 24 hrs.

The beach shrimp had a thick clear gel mucus on the shrimp and it reeked
bad! My tank sand barely had any growth (if any) and not much odor.

So, is this a reasonable test? If so, do I have "dead" sand?

Reason being that nitrates are not getting processed very quickly out of
my tank, and I'm trying to figure out why. My aquaculture neighbor is
encouraging me to put some beach sand in the tank to get the nitrate
eating bacteria growing. I've been letting the sand "stand" in a bucket
for a few days to see how the "test damsil" does (still with us).

--Kurt