Utilizing existing 750 gal fish pond

[multifasited]

Hi from Cartersville Ga,I have a unique pond set up ,consisting of twin ponds conected by a waterfall 18" to drop lower pond 2' deep ,upper 4'x12' x12"deep . bottom pond ,has 1/2hp sump pump in capped milk crate w/course comm. scrub pads surrounding pump ,travel thru 1 1/2"pvc sch 40 pipe thru check valve -Gate valve to a tee feeding 300 gal bio tank,and 55 gal sand and gravel filter second valve meters flow to each ,5 liter air pump to bio and ponds via air stones,water exits each filter dumps into gravel trickle tower in SS weire at water fall into SS final filter aeration and dispersal collection box at water fall at upperend of upper of the .long pond ,second water fall also has same ssffa box w/o TT. The upper and lower ponds have connected 1/6hp pump fed bottom sweeps ,upper pond has 1 1/2" linear bottom pipe half slotted connected to a third sealed sump pulling thru that 1 1/2 pipe for is feed pumping to the bio tank for waste removal. pix below ,after that longwinded disertation ,the QUESTION I am thinking of adding ! or maybe 2 bci 4x4 x14" GTs with constant flow from the upper drain sump to feed the gbs ,w/auto=bell vac drains back to my bio tank,or I could go back to the upper pond directly this pond supported 80 -6-8" gold fish ,all suggestions welcome before I build and decorate to match existing . This is my front yard 10' off my frt. porch ,I set 800' off of the road.I am interested and anxious for all replies !! Got the fever and want to do it right the first time ! Thanks ,Carl