The pool is safe for swimming pH wise -- it is NOT necessarily safe, chlorine wise.

If you had an acid demand test, why didn't you report your alkalinity or your base demand? We have to treat reports of pH = 6.8 as what they really are with most testing method -- 6.8 or LOWER. That is, your 6.8 might mean your pool was a liner-damaging 5.0! But, if you'd posed a base demand, I could have responded more specifically.

You can use either muriatic acid or sodium bisulfate (pH Down) to lower the pH; replacing 10 buckets full of water will have no effect.

Please report a COMPLETE set of test results: including chlorine level, pH, alkalinity, calcium and stabilizer. (If you haven't added any chlorine or stabilizer, you don't need to test for stabilizer: there is none in well or tap water.)

BUT . . . you'd better add some chlorine quick, or you will have a green pool! Again, the SS Recipe will give you a place to start.