That Pine Sol smell is Mountain Dew and the dark sludge is probably Pepsi. We get used syrup barrels from the local bottling plant and it's amazing how strong they smell, even when empty.
Check out BrewCipher. I've used it for a few months now and really like it. It does have an OG function for automatically adjusting grain amounts based on percentage.
https://www.beeradvocate.com/community/threads/brewcipher.141602/
I got one 60 second use out of mine then the next time I went to use it, it was empty. Afterwards I read on here that they are known to leak. I now unscrew the regulator after every use and the bottles last a lot longer.
Since you're using a stir plate I would remove the air lock and use a foam stopper or sanitized foil. You're not letting enough oxygen in for the yeast to reproduce.
Also it may not be too late to add 16oz of water, but I'm not sure on that.