Tank level gauge for black water in 60c?

[oceanjake]

My ‘83 60 enclosed bridge has a fresh water gauge but no waste gauge. I don’t see a sender in the top of the tank either near where the hoses are plumbed. Does anyone know if a sender was included in 1983 or if one must be added? And if one must be added, how difficult is this in a fiberglass tank? Ideally, the gauge I have for fresh water can be used, as it has a two position toggle integrated in it. Thanks for the help

 

[SKYCHENEY]

Originally there was a 1/4" copper tube that hooked to a pressure switch enclosed in what looked like a red hockey puck. The tube would rot off after years in the tank and would no longer trip the switch. The switch turned on a light in the head labelled "tank 3/4 full".

The best solution is to install a Hart tank tender. Its just an 1/8" plastic tube connected to a gauge that reads in inches. Very accurate and won't degrade in the tank. Also won't foul with paper, etc like many other gauge types.