Hi MoodyMaMa,
welcome to TFP
First off, forget EVERYTHING the pool store told you.
Why? Because with a vinyl pool, you dont even need calcium in it. There is zero chemical reaction between Vinyl and Calcium.
Unfortunately, like so many others, you have been 'pool stored'.
Ok, with that off my chest. (grrr on that pool store).
If your water is clear. Thats good.
If your CC is .5 or less (one drop to go clear) Thats good.
Next, do the overnight chlorine loss test.
When the sun goes down, test.
Before the sun comes up in the morning, test.
If your OCLT is 1 or less, then no need to slam.
If you loose more than 1 FC - slam.
But First, get some chlorine in your pool. Its way to low. The FC to keep your pool clean is based on your CYA level. With CYA of 67 (lets call it 70) your target FC is 8. Thats what you need to keep your FC at. Here is a link to the FC/CYA chart.
http://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock
ONLY use liquid chlorine (bleach from Walmart or wherever) or Salt Water Generator as your primary chlorine source.
Do you know how to use Pool Math? You need this to determine how much stuff to add.
At top, enter your volume of the pool *at bottom of pool math, you can calculate volume* 20x20x(3+9/2) = 10600 gallons
[I added your shallow end and deep end and then divide by 2 for average depth]
Ok, so enter volume
In the boxes on the left side, enter test result
In the boxes to the right of it, enter your recommended level, and click the caluclate button. Pool math will tell you how much of something to put in. Its pretty much that simple.
Pool Math
http://www.troublefreepool.com/calc.html
Recommended Levels
http://www.troublefreepool.com/content/134-recommended-levels
I hope this helps.
I have shocked as directed by pool store over and over and gone through a $100 bucket of calcium chloride(? ) and still the FC level is 0.2-0.4. I have given up on the stores help and want to figure this out! Bought the test kit recommended here. I added one gallon of bleach and the next evening the FC level was the same.
FC - 0.4
CC - 0.4
PH - 7.4
Alk - 100
CA - 230
CYA - 67
My plan was to slam it, but the cc is under 0.5 so does it really need it? Water is clear I have seen a bit of green on the ladder steps no where else. I am having a graduation party at my house next Sunday and want to have the pool safe to swim in!
Also if I need to add lots of bleach do I add it all to the skimmer?