How to plumb aquaponics systems that are far apart?
Augmented siphon:  one pump and a perforated pipe.
For this scheme you need a serious pump and a perforated pipe on the plant side.

Your pump pulls water from the fish tank into the plant tank.  The water is pushed into a PVC pipe along the side of the plant tank near the top.  The PVC pipe is perforated such that some of the pressurized water leaves the pipe.  Some water from the plant tank enters the pipe.  I considered also using a drip hose for this but I think the inside of the drip hose would eventually get clogged with particulate waste from the fish side.
Water entering the pump side of the pipe will be under a lot of pressure and much will escape thru the holes of the pipe.
Farther down the pipe the perforations end.  There is a second smaller pipe joining the formerly perforated pipe at a steep angle.  The idea is that flow in the large pipe produces a Bernoulli effect and low pressure where the pipes join, causing water to flow in from the plant tank.
At the end of the large pipe is a hose leading back to the fish tank.  Pressure in the perforated pipe is lower now but still higher than the outside water, and so enough to push water up and over the top.  Once it has made that little climb the water will go downhill back to the fish tank.
This has one pump which is nice.  Some water from the fish tank will make it thru the perforated pipe and be returned to the fish tank which is not a tragedy.  If the pump stops, nothing will flood.  If the water level rises in the plant tank there will be more pressure assisting the siphon effect on the return circuit.
Obviously with too many perforations all the pressure will be lost in transit of the pipe and there will not be enough left to get over the top.  Too few and you will just be circulating water from and back to the fish tank.
I have this idea that more is better: as pump strength increases you will push more water out the perforations and also have enough residual rapid flow to maximize the Bernoulli effect and intake thru the angled intake pipe.
Ultimately the outflow thru the perforations needs to match inflow via Bernoulli effect.  This is the point where the architect hands the plans over to the engineer.