I am going to be replacing a gasket on my Pentair Multiport. It seems like the last time I opened up the multi-port, I had some DE leave the filter and end up in the pool. Is this possible or am I thinking incorrectly? Maybe it happened when I left the air relief valve open on the filter? I'm thinking that if I shut off both the skimmer and main drain suction lines, there is only so much water that could leak from the multiport??