I'm imagining that the fountain-filter pump was engingeered to work selectively: when the duo-load feature was chosen the machine would fill first with only the amount and temperature of water required for the mini-basket. It would pump it up into the basket via the agitator fountain and then subsequent water intended for the main tub, wouldn't be diverted into the "fountain". They even might have used a Filter-flo style pump attachment to do this as the Hotpoint fountain-filter "pump" was the agitator itself. Because the Hotpoint was still a solid tub machine, when the wash water was thrown, there would only be incidental mixing of the two waste waters at the beginning of the spin. This feature wasn't around long--only one year, I believe before GE cut bait and eliminated real Hotpoint washers, turning them into FrankenGE's. This was a line that CU helped kill.
I need to get my hands on the 1969 Consumer's Reports issue that tested washing machines. One of the negatives that it described in great detail was how the Hotpoint agitator assembly would have to be completely disassembled to get rid of sand! There were even pictures of it and it looked like a massive undertaking. CU thought that the Hotpoint mini-wash system worked better and used less water overall than the GE's but it rated the Hotpoint machine at the bottom of the list. Most of the last remaining solid-tub machines, including Frigidaire, kept it company. I think it was one of the last CU reports that included now extinct brands like Blackstone, Easy, Wizard, Hamilton and Philco (sigh!).
