nkd5025:
Vasco,I want to thank you as seeing your controller a few months back was one of the main reasons I decided to try and make my own. For ATO I have implemented freescales MPXV5004GC7U pressure sensor in order to get accurate water levels. It is extremely simple to use and is quite accurate. Here is a link to the product
http://www.digikey.com/product-detail/en/MPXV5004GC7U/MPXV5004GC7U-ND/951844Nick D.
That's the good find! (and not expensive:)