No problem with the questions.

Chlorine => 25% of your CYA => ~35 ppm or HIGHER!

The other option is to use phosphate remover. Mustard algae is VERY chlorine resistant. I'd recommend first trying 35 ppm + daily brushing, and see if you can eradicate it that way. It's much easier to remove mustard algae from vinyl pools than other types. Do NOT use any of the mustard algae products -- they ALL have horrendous side effects. Don't bother with polyquat; it's not very effective against mustard algae.

If you want, you can try borates. Raising your borate level to 60 ppm improves the aesthetics of the pool water somewhat, and helps with green algae. It may help with mustard algae somewhat, AND it will help with winter maintenance. If you want to pursue that, you'll need 22 boxes of 20 Mule Team borax and about 6 gallons of PLAIN 31% muriatic acid, like the Crown Muriatic at Lowes

The remaining option is using a phosphate remover, but doing so successfully requires a definite plan and consistent efforts on your part. Simply adding phosphate remover without a plan and without accurate phosphate testing is likely to be nothing but a waste of money.