new system build in louisiana

hello to all, building a shedding system for home/ possible small scale commercial.

2x6 tank with a very overcapacity pump and pool sand filter combo that was given to me by a friend.
planning to use a combination of oyster shell and plastic beads in the system as biofilter media.

the tank drains into a 55 gallon drum set up as both a reservoir and a component of the biofilter.
it will be set up as a bottom drain sump filled with oyster shell in the center held in 2 large baskets.

they Will be stacked on top each other with main pump discharge returning into the center of these shells

the water will flow out of the sides of these baskets and fill the outer part of the barrel which will be filled with pea size plastic beads.

from there the flow is directed into the sand filter which i plan to fill with the same plastic beads. ( they will sink ) to act as not only a bio filter but as a particle filter

if i calculate the tank volume correctly when in operation the water level will be about half way up the 55 gallon drum sides leaving most or the upper shell basket exposed to air but being sprayed with water from the center core as this is where the main discharge will be.

another areation point in the system.

the feed to the tank is a 1 inch line fed off of the 1.5 inch discharge line of the pool pump as it goes back to the 55 gal drum to recycle through it frequently both filtering and areating with the spray through the air exposed oyster shell basket.

the 1 inch tank feed line will end in a spray head at a 45 degree angle to promote tank circulation.
the stand pipes are set up with bottom flow covers to cause bottom water to be drained back out of the tank and back into the 55 gallon drum to be run through the process again

anyone see any flaws or problems that i may encounter? i will try to take a photo when i glue this all together and have a photo worthy setup

please let me know of any ideas good or bad you have about this design.

thanks