Grey tank

[Peterf]

Emptied 37 gallon (?) tank yesterday 0% full. Parked level in two directions. Today added water in 5 gal increments. At 5 gal 13% full. 10 gal 38% full. 15 gal 56% full. 20 gal 81% full. 25 gal 100% full... at 35 gal there was about 2 gal of new water in shower pan. There are two questions here, first is about how the tank measures and how to calibrate if not accurate. Second is about a 37 gallon tank holding no more than about 33 gallons.
Will these readings ever get accurate? Thanks for anyone’s thinking on this.

[Alumaholic]

The instructions for calibrating the SeeLevel system came with my 2019 FC 27 FB.
Did you check your stack of stuff?

[brick1]

I did the same thing recently with my grey tank. Added one gallon at a time, recorded the results (don’t judge). My tank was also at 100% full with 25 gallons. So about 10 gallons left to go. Sounds like that may be how they are calibrated.

[mikeinca]

Probably an unnecessary question with an obvious answer, but did you close the gray tank valve as soon as it hit zero or did you let it continue to drain for a while longer? Although the calibration issue is bad enough, the possibility that the tank doesn't hold the amount of water advertised is also concerning.

[brick1]

I went all the way to 30 gallons. No water in the shower pan. I figured that was close enough.

[Peterf]

Hi Alumaholic. The SeeLevel II manual covers led brightness, installation and placement of the senders. Suggesting temporary placement of the strips until satisfied with readings. Doesn’t explain any re-calibration that would correct for discrepancies. Still confused about 37 gal capacity. Emptied tank until it just dribbled and read 0%.