Can I get some help with pump choice?

So I've got a "fish tank" that's about 800 litres of extremely salty water. I need to circulate this through a filter. I have a 50sqft cartridge filter. I previously got an Iwaki MD pump which was about ~1000LPH flow rate, think it had only 1.5m head or something, and it couldn't even push the water past the flap at the bottom of the filter.

I ended up buying a 3000LPH transfer pump with like 30m head or something ridiculous like that, this worked. However it rusted coz of all the salt.

ACTUAL QUESTION/TL;DR: Will a PanWorld 100PX be strong enough to push the water through a 50sqft cartridge filter? I don't need massive flow rate (turnover 3x an hour or whatever people say). It's ~3000LPH as well, but only 6.5m head.

Also would an iwaki MD-70R work? Or any other suggestions? Thanks!