There was a product called the nurse. It was an automatic top off system. I think it worked on a syphon system. The principle was a container made of acrylic that held top off water according to the size of the container. The top had a cap about 2 inches in diameter with 2 pieces of tubing coming out of it. One was for the container and one went to the sump. I would like to make one or have one made for me. Does anyone remember this product?