The first time I cleaned out the Formlabs wash unit, I followed the needlessly complicated instructions of siphoning out the isopropanol tank, but I have since discovered that the tank can be easily removed and dumped out. I documented the simple process in a BitChute video.
The only reason I used the siphon pump at all in this one is simply because trying to pour from a fresh 5-gallon IPA drum without spilling it is damn near bloody impossible. Next time I replace the IPA, however, I'll be able to simply pour it in.
I recommend the Form Wash for anyone who runs a stereolithography machine, whether it's a Formlabs printer or not. You can get it here: https://formlabs.com/store/post-processing/form-wash/
Formlabs recommends a minimum concentration of 90% isopropanol for the wash unit. Rubbing alcohol, for comparison, is only 70% IPA. As you can probably see from the video, I get mine from Uline. However, as of this recording, Uline is shipping IPA only to existing customers for the duration of the current pandemic. Nevertheless, here is the product link: https://www.uline.com/Product/AdvSearchResult?KeywordTyped=iso&keywords=Isopropyl%20Alcohol%2099%25