Another SeeLevel question & a blooper

Another trip out last weekend and had a great time!  Trailer towed excellent and only one small minor mishap which was totally my fault and a "duh" moment.  I forgot to raise the crank up high enough & forgot to take the wheel off--made it about 50 yards & said "something's wrong!"  Had to back the rear tires of the truck onto a couple of legos to get the wheel off--Luckily didn't bend the jack post and only scraped up the wheel a little more- - - - I got in a hurry --duh 

So anyway--The fresh water tank never came down from 100% and the grey level never came above 0%.  We were using water did have grey water come flowing out at the dump station.  The SeeLevel for the black tank and battery seemed to work OK.  I guess it's better to have a more accurate gauge on the black tank than the fresh & grey water, but they seemed to at least register something last trip??  I was almost dead on level.    Last trip the fresh & grey water levels were significantly off but at least they worked.  Now I can't tell if my fresh water tank drained completely.  I did open the fresh tank valve and left it open on the 2 &1/2 hour drive back home.

Any thoughts?