White foamy residue on pools surface...

[Beanns]

Hello!!
I have a white bubbly residue on my pools surface and so i took the water to get tested. Hopefully I can provide enough info so that the experts can help me with this problem.

FAC: 0
pH: 7.4
TA: 30
TDS: 300

The pool store associate told my father to add 21 lbs of Alkalinty UP (Leslie's Pool Supplies) and then 4 lbs of Shock.
Pool store associate did not state levels of CYA (my father took the sample and doesn't know any better).

I apologize if I missed anything. Any input of how I can stabilize my pool would be very appreciated.

Thanks!!!