Fire your pool store.

With a CYA level of 70, your FC needs to be a MINIMUM of 5ppm. If you have an SWCG (saltwater chlorine generator), it needs to be a MINIMUM of 3.5ppm.

So FC of 3 with CYA of 70 is definitely NOT perfect and at risk of algae growth. Other numbers look OK for a vinyl pool.

But...if you find your pH isn't stable, you'll want to lower your TA. If, however, pH is stable, you are fine--don't fix what isn't broken.