Although I never have had a big problem with the stock cheap tank sensors in 30 years, I never really liked the accuracy of them. And then one day I saw on this forum something that changed my RVing life forever.
Someone had installed the SeeLevel tank monitoring system. I looked into it and installed it shortly there after. I couldn't be happier.
I installed one monitor inside and one in the water fill bay. The gauges are very accurate and the sensors mount on the outside of the tank where they are not affected by crud on the sensor tips. I even added the propane level monitor.
Worth every penny and makes monitoring levels much more accurate. When filling my tank I can watch the level come up so I know when to get ready to shut off the hose. 90% of my camping is boondocking so I am constantly topping off my tank. I also feel better while dry camping knowing how full my holding tanks actually are.