I have a Triton TR60 sand filter that needs its sand changed. I have removed the drain plug, removed the clear plastic dome on the top, and disconnected the two lines on the side. Looking down inside the filter from the top I see a circular shaped device that is in the way of removing the sand through the top. Is this piece removable or do I just have to work around it? It would be much easier to get the sand out if I could take this item out but it feels like it is firmly attached and I don' t want to break anything. Any help out there?