When you say you flush for a minimum of 5 minutes, can I safely assume you are using your black tank flush, not just letting the contents flush by gravity?
When you flush, do you (for short periods), close the BT valve and let the flush run in the tank, then open the valve. I do this 4-5 times every time I dump. I use the BT flush every time I dump.
Also, Jagiven suggested you add several gallons of water to your tank once you have ceased your dumping process.........along with adding RV BT chemicals.
Good luck with it.
Darrell, Mary & K.C. Toller Mix
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