Eric is right, and not just different size (ID) tubing but different rollers as well. There is a reason for that: to prevent waste of spot remover. Our Doyle units had the same larger-bore tubing in both pumps, and I was going through three times as much spot remover as shampoo, even though it was used much less. Replacing the tubing and rollers with the ones Fragramatics uses in the spot remover cut the usage down to 20% of what it was, and it even foams better.