Yesterday evening my pool started venting water from the wast pipe I turned off all the valves but it still continued to vent. I rotated the multivalve to off and it seamed to stop. My wast pipe runs from my pool to wast ground which is over run with weeds. I then rotated my multivalve to the normal position and everything seemed OKl. I kept a check on the water level and it did not go any lower. This morning I started a full investigation and found my ballast tank full to overflowing and it should have been half full. I went to the jungle where my wast pipe emerges and discovered the overflow from the ballast tank next to it. THAT'S where the water was leaking. I checked the one way valve from the ballast tank and their was debris in the spring. I assumed that it had jammed but then cleared itself. I am writing this just to let you all be aware that the water can back-feed into the ballast tank if the valve sticks open. I lost around ten tons of water, which was better than I expected.
All well that ends well, at least I found the problem.