The DOC skimmer can work as a closed loop skimmer like the current model in tank or a full sump like you will have or as a open flow through model in a low water level sump- much like a Euroreef. I would wait even though you won't be able to make full use of the flow through feature because, you will save $30, the performance will be slightly more and you can upgrade through all the range as you need. You won't gain much performance because with a full 11" or more water line it has to run in closed loop to avoid a big discharge of microbubbles but with the dam you have for the sump section it is concievable you could run it open if the flow through wouldn't be enough to carry bubbles back into the tank.