If you are really determined to save it, here's what I suggest:
Transplant it to a smaller container like was previously mentioned. I know that you think it's using the whole container for it's massive root system -- it isn't. Maybe it does have roots going down to the bottom, but whatever..
Just dig it up, and only use a few inches of it's rootball to transplant with. It may be shocked for a couple of days, but it will grow after that. I would suggest using a 16 oz party cup to start with. Also, I like to drill half a dozen holes in the bottom of the cup and a dozen or two more holes in the side of the cup, so that your plant's roots can breathe -- it really helps in party cups.
It's really the only way you can control your grow. The 5 gal container is way too big for that tiny plant -- you are just stunting it's growth. Also the 8.0 ph is way too high, but you will never be able to get ahold of the ph in that container at this point, I guarantee.
Transplant that plant into a more appropriate container today. Do it now. Don't ask anymore questions, just do what I said, if you wanna save it.