Oh, Pony! I sure hope you listened to Watermom and canceled those guys because you have been "pool stored"! (We all have--that's why we are here)

I would NEVER add 20 lbs of baking soda to ANY pool! It caused your total alkalinity to shoot up to 190--which is luckily OK because you have a vinyl pool (it would have added to your problems if you had concrete or plaster). However, it is NOT the best way to raise pH (which, at 7.3 is FINE, especially since you are fighting algae).

Sand lasts forever unless you gunk it up--and about the only way to do that with a chlorine-sanitized pool is add all the junk pool stores gleefully sell you that doesn't work when you have algae!

'Mom has you on the right track. She's giving you simple, unambiguous instructions of things to do RIGHT NOW. They WILL work, and work well.

Later on, we can address WHY 'Mom says never let your chlorine go below 5ppm.

But for now it's the old "alligators in the swamp" situation!