Good grief! " Superthrive 1/2 tsp per gal"

Re-read the label instructions on the S.T. bottle.
That much will hose adult plants!

IMO Superthrive is snake oil anyway.
But that does not make it harmless.
Quite the contrary.

And you will do well to ignore this outdated advice ; "tap water left uncovered for 2 days".

Most newbies do that.
It's "what they read somewhere".
Very few water supplies still use Chlorine gas for disinfection.
If your water is treated with Chloramine leaving it sit is counter-productive.
All that will dissipate is any dissolved air.
Unless you replace that air with an air-stone or an in-line aerator, your plants will suffocate for lack of Oxygen to the roots

"they keep curling up!"

I'm not clear here.
Are they really curling up, or are they "clawing" down?
There's a big difference.
Pictures would help a lot.

When you say; "Source water pH---5.8"
That can't be from the tap.
So, I'm guessing that you adjust it with PH down.
What kind?

That would also indicate that you have the means to test PH.
If that's the case.
It's more productive to test the res. water every day.
You did not pre-treat the RW or the 'tron?!
I'm willing to bet that your res. PH is quite high and rising.

All that said, if you carefully read the labels and read through the archives here, you might not have to start over.

Test your res. daily.
Purchase a thermometer with an RH readout.
(3 or 4 bucks on da E.)
And at least borrow a camera.
Then get back to us, yah?

Be real happy to help, but ya gotta do the homework.

Aloha,
Weezard