The biggest issue is how hard calcium concentrate is on this style of pump. Exact same issue with pumps in kalkwasser. I'll never understand the thought behind them (and alot of other companies) using such high dollar pumps for such corrosion liquids.
Using an external style (iwaki, dart, even little giant or generics, etc...) is a lot more intelligent of a decision.
I had a refugium/sump dwelling serpent star decide to plug the water inlet on my VarioS 6S skimmer pump melting a hole in the rear interior of the pump where the little circulation holes are (he lived but figured out the dry run protection from Reef Octopus is absolute bs).
One thing I will say is though to answer your question, you can easily replace the original with a jebao dct or similar style pump. I'm 90% the sure any of the 4000 series will be a direct replacement inlet and outlet size and a ton cheaper. A jebao dct-4000 (I believe) is what I replaced my VarioS 6S with because if I remember correctly the dct-6000 uses a longer impeller causing to error out when I tried to use the needle wheel impeller because the size difference caused awkward rotation of the 6S impeller. The dct-4000 was a direct fit and has been on the skimmer over 18months without issue.
