Fitting a fuel polisher

[pcatterall]

Tried on line for a clear answer but its back to my favourite group again!!
We have two 50 gallon tanks on our Neptunian . One is the master and the other has a pipe joining the tanks so that fuel levels can be examined.
We installed a fuel transfer system which include a CAV filter. It has worked OK but rather slow.
The pump. has to sack up a maximum. Of 50.cm when a tank .is low and then pump up another 50 cm to deliver fuel.to the receiving tank. Currently the fuel in the slave tank is low and I.cannot.get fuel up even into a container at pump height. Pumping the other way from a full.tank is working fine I cannot recall the size of pump.we installed but physically it's around 16cm x 5cm .Do you think the existing pump is not man enough for the task or is there any advice on offer.
Thanks for reading!!
Any advice on the size of pump

 

[Refueler]

Peristaltic Pump is what you need.

 

[NormanS]

Don't know if this is any help, but like you we have twin 50 gallon fuel tanks. Ours are each on the same level, so can be cross leveled simply by gravity.
Sometimes towards the end of the season, both tanks don't have much fuel in them, so I like to put it all into one. I simply use my dinghy pump. Temporarily block the breather pipe, wrap a rag round the end of the pump hose, and gently pressurise the tank to be emptied. As soon as gurgling noises are heard, shut the outlet on the now empty tank, and tell my wife to stop pumping.
No pump required.