I am restoring a vintage TC which currently only has a black tank. It's been 30 years since I was last involved with RV's so memory is a little fuzzy. I'm guessing you can tell if the black tank is full just from looking down the open ball in the toilet and viewing the contents is that correct ? I am going to add a grey water tank and it seems like many folks state the electric sensors/gauges for showing tank levels don't work or are not accurate. So assuming no electronics are involved how do you know when the grey tank is full ? Is it just that water stops flowing down the drain ? I know these seem like stupid questions but I need to know. Thanks
