Another "thumbs up" for Tank Tender. We purchased our Grand Banks in Vancouver and then took her home to Squamish. The first stop after leaving the brokerage at Granville Island was to stop at the fuel barge for a splash of diesel; the Tank Tender showed that four of our six tanks were about 25% full so I just poured a half paycheque into the two almost empty tanks. After fuelling I didn't read any change in the two tanks...strange. Only later did we discover that the Tank Tender was in fact not functioning at all. ALL tanks were just about dry when we left the brokerage and it was just dumb luck that saved us from running dry in a very busy waterway! Long story made short is that our boat had been in charter service prior to our purchase; somebody must have monkeyed with the gauge at some point and over-pumped it. That being said, Tank Tender's customer service was exceptional and we had a replacement head unit at our door in two days. The unit has performed flawlesly since (and we never let kids or idiots near the thing).
FWIW, our boat has new tanks, for whatever reason they chose not to install sight glasses at the time, a poor decision that I hope to change if and when I can.