OK, I want to make sure I have this right so sorry this is probably a repeat question. I have done a lot of reading so tell me if I have this correct. I want to add the IBS to my 07 LSV without drilling holes and adding new pumps and the whole 9 yds. I just want to fill and drain it through the ski locker ballast bag. So I will add a line to the front (closest to the bow) of the ski locker bag and run that line to the starboard side of the IBS. So once the ski locker bag is full it will then push water into and fill the IBS. So this is where I am not quite sure...I then add a vent line to the IBS that will "T" into the existing drain/vent line that comes from the ski locker bag and goes out the side of the boat? and I also need to add a check valve to that same drain/vent line right before it goes out the boat? What is the difference between a spring loaded check valve and just a check valve? Which one do I need? I have also read about putting in a 3 way valve but since I always plan on filling the IBS along with the ski locker bag then I don't need this right? Sorry for the hand drawn picture but this is how I have it in my mind..