Z3 pro ballast hose routing

[mnpracing]

I'm getting ready for a ballast upgrade, and wanted to make sure i understand how the stock hoses are routed in the pro ballast setup (just in the rear compartments). Here's what I think happens:

1. The fill side for the tank and the bag comes in through the top of the bag and then gravity feeds into the tank
2. Then the drain for the tank and bag is connected to the backside of the tank, and the bag gravity drains into the tank
3. How are the vents routed? Do the vents or drain lines have check valves? Are the drain and vents T'd together to one thru-hull?

Thanks in advance for input/corrections.

[chpthril]

The fill line T's off to the in-floor tank and to the top/forward port of the sac. The water flow will fill the tank first, since the sac may be folded up in the stowed position. With the sac deployed, water flow will take the path of least resistance on fill the the tank first. When the tank is full, the resistance will steer the water through the other outlet of the T to the sac. At the same time, water will still flow up through the two bottom ports from the tank into the sac.

The top/rear port on the sac is the vent. The hard tank also has a port. The two are T'd together.

The drain pump is connected to the tank. As water is pulled from the tank and the level drops, water will drain from the sac into the tank.

No check-valves in the drain or vent lines that i'm aware of.

[mnpracing]

In the 2013's I poked around and confirmed that the bag vent is at the top front of the bag and the fill goes to the top rear. The 2012 however has this reversed. This should help it vent better since the air pocket would be at the top front of the bag.