Whenever I try to change the hose mode, it just switches to the other Hotbar slot and not the new hose form. When I press N, it just changes the tank.

First you have to attach hose to backpack (By clicking Right-click) then click "Z" (Default) + Mouse wheel

change hose mode you need hold hose, and press shift button, than rolling your middle button of mouse.

I am having the same problem. doing the correct input Shift+mouse wheel while holding hose but it doesnt change mode, it just moves to the next hotbar slot.
and as said a while ago a hose in your offhand /shield hand will delete the hose....

OK, i know what happen now,
because the mod change the swap button, so now you need press "Z" +mouse wheel.

Still dont works to me.