I beat the drain monster! He has retreated, ceding victory TO ME!!!
At the start of Round 5, I took the u-pipe off yet again to empty all the standing water, reattached it and poured a ton of vinegar and baking soda into the pipes. Oh the fizzy goodness of everyone’s favorite chemical reaction! I let is sit for over an hour, then plunged some more.
So I took off the u-pipe for the millionth time and drained the solution. Then I stuck my diaper sprayer into the pipe and blasted it. The pipe filled with water, then spraying out the sides of the mouth, then drained out when I stopped the spray. I did this a few times, and the last one I held the sprayer on there a LONG time, blasting the water as hard as I could.
When I pulled the sprayer away that time, no water came out. It was finally draining!
I HAD DEFEATED THE DRAIN MONSTER!!!!
I danced a victory dance. And almost slipped and fell on my ass.
I reattached the u-pipe yet again, and poured boiling water down the sink (it was my final line of offense and I wasn’t going to waste the huge pot of boiling water), then turned on the faucet and watched it drain and drain.
I have no idea what could have caused such a major blockage, but I’m really glad it’s gone. I would have been so pissed to waste a day on that and then still have had to pay a plumber to fix it.