Black holding tank won't drain past 2/3
After 4 days of camping we have a full holding tank. I open the black valve and hear a rush of fluids for about 1 min, then nothing. Check the tank level inside and it shows 2/3 full. After searchi...
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It should be noted that most black tank flush (external) hose attachments require the black tank valve to be OPEN during the flushing period. Just an FYI :)
