For cleaning the tank and sensors, try a product called RV Digestit. You can use it to clean sensors and tank, or just as a tank chemical. I assure you it'll work if you follow the instructions. To clean tank / sensors, 1 bottle to full tank of water, let sit for 48 hours plus, dump and flush. You'll get crap out of a tank you didn't know was ever there. We have used the Geo method, and it works, but also have our home brews. I can't leave well enough alone. It's a crap tank, experiment a little. I'm always trying different things. Water softener plus (pick an additive - purple power, pine sol, dawn etc). Have yet to have an issue with sensors or having a dirty tank. I know the Digestit stuff works as I've seen the results from other's rigs.
John and Rebecca Dickson
Emma-8 / Little John-5 / Iva-1+
2013 Ford F-350 Lariat FX4, CC LB PSD, DRW
2015 Jayco Jay Flight 28BHBE (#8)