That's a mistake in the manual we have to fix as far as water level, since the splash guard is adjustable that suggestion needs to be more specific.
As far as Okeanos specific kiss carts, you can tell them apart from the center pin on the bottom. If that center pin has a hole then it can be used on the Okeanos.
White orings where changed to red orings, so your good.
As far as water being pulled down is because of two reasons working together.
1 our messed up water level in the instructions and since the water level was to high a slightly blowing into it will reverse the water flow and siphon effect kicks in and pulls water down.
Hope this explains all your concerns.
As far as Okeanos specific kiss carts, you can tell them apart from the center pin on the bottom. If that center pin has a hole then it can be used on the Okeanos.
White orings where changed to red orings, so your good.
As far as water being pulled down is because of two reasons working together.
1 our messed up water level in the instructions and since the water level was to high a slightly blowing into it will reverse the water flow and siphon effect kicks in and pulls water down.
Hope this explains all your concerns.