Pretty much what bubbles said x2. I dump it, fill it for 5-6 minutes, dump it and so on about 4 times. I use the same water and sewer hook ups in the shop just about every time, so I'm comfortable with my timing. First couple of times, I started with the empty tank, started the water and the stop watch, went inside and watched through the toilet until I was satisfied with the water level. This is where I established the 5-6 minutes. Key is, don't get side tracked. Had that happen once and dang near made a mess. Another thing that we do 99% of the time, is either wait until we get home to dump it in the shop, or wait until after a days travel and dump at our destination if available, this way it's all churned / mixed well. We also use the "Geo Method" opposed to the typical chemical you put in the tanks. Do a search and you'll find all kinds of info on this. Pretty much a home rememdy that works in my opinion, better. 10 years+ on the road cleaning the tanks as mentioned, and I haven't ever had a sensor go bad or a line clog. After the tanks are cleaned, if the RV is going to sit for a few weeks, I'll put some water and pine power (dollar store version of pinesol) in the black and gray tanks. Makes the toilet smell like a clean kitchen.
John and Rebecca Dickson
Emma-7 / Little John-5 / Iva-1
Full Timing Again, Rev B
2013 Ford F-350 Lariat CC LB PSD
2015 SOB TT - With OC's Awning Poles (#8)
At least in Heaven, RVs will be perfect, and I won't have to keep fixing them.