New pool owner, need some guidance please

[PoolDoc]

Take a look at the "Best Guess" page, linked in my signature. You need higher chlorine than what they said. I wouldn't worry about the baking soda, unless your pH is unstable.

Given your recent algae, I'd think more in terms of 6 gallons of plain 6% household bleach (or 3 gallons of FRESH pool chlorine).

You need to test your stabilizer. I'm assuming your dealer is using strips, which aren't very accurate. But if you really have 100 ppm, you are going to either have to drain or run high levels that require a FAS-DPD kit to measure.

[Watermom]

A pool store that tells you that total chlorine and combined chlorine are insignificant? Uhh, that's a bit concerning.