Acu-gage
I have purchased but not yet installed a tank guage system called Acu-gage. This is a panel that monitors up to 4 tanks, using external electronic sensors that require no penetration of the tank. This arrangement can't leak, clog, rust, etc. Don't know if they work yet, but it sounds good. Cost is a lot less than mechanical guages. Here is the Web site:http://www.snake-river.org/I first saw this product mentioned on this forum. One problem is that to install the sensors, you need access to one full side of the tank -- makes it difficult with foamed-in tanks.