ignore them ....
As already said, the tank lights are unreliable, our fresh tank showed 2/3 full the day we picked up our brand new Micro Lite 25KS(tank was empty), ... even if they are working perfectly, when the black tank light shows 2/3, you/I don't know how close it is to completely FULL, with our 30gal tanks it could be another 10 gals or it could be just one more 8oz flush before the FULL light comes on, you don't know, ... I don't trust um and don't look at um, ... the fresh water tank is translucent so I can look under the trailer and see its level, ... I know the gray water tank is full when/if it shows in the shower(it's gray water, no problem), ... our toilet has a direct look into the black tank, looking down into that tank is the surest way to know its level, but when you open the toilet valve to see, the water flow prevents getting a good look, so installing a shutoff valve on that water line solves that and is beneficial in other ways, ... if you ever get a leaking toilet valve, that shutoff valve will allow you to stop the leak and give you control over that issue until you can get it fixed without having your campground stay interrupted, or if boondocking where water control is utmost important, you have complete control over how much water the toilet uses, .... that is just my take on those LIGHTS, .... pics are of the shutoff valve I installed, ....
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