Hello, Thanks for all of your replies, I shall give them a try. We actually live in England but it seems that EParcyl isn't very popular here, hence my question on this forum. Our "tank" is set in chalk and according to the company that last emptied it in 2012, they think it probably leaks out causing it to not need emptying very often. Does this mean that a product like EParcyl is even necessary for this sort of system?