Hello, this forum is awesome, learned a lot already, but I have a bit of a problem, we just bought a house with a pool YAY !!!

My problem is scale, I have been using a Taylor 5 way test kit and the AquaCheck test strips, when we first moved into the house the pool was green, due to lack of care during the closing of the loan, I got taken care of that by lowering the PH and adding liquid chlorine, since the water cleared up, I noticed several stains in the bottom as well as scaling of the ladders, the pool was just resurfaced by the seller and a whole bunch of plaster dust had settled on the wall and bottom, I actually cant tell if it was scale or plaster dust, fast forward a couple months I did a zero alkalinity treatment, the pool is a kidney shaped one an about 20K gallons, I added 10 gallons of muriatic acid for 2 days while brushing non stop (4 times a day) by day 2 the staining was gone and the water was a bit cloudy, quickly raised the PH by adding 3 lb of Borax, and raised the chlorine level to 5 ppm, ran the pump for 48 hours and took my water to get tested this are the numbers as of last Saturday.

PH: 7.6
FC: 3 ppm
TC: 3ppm
CC: 0ppm
TA: 100
Total Hardness: 500
Calcium Hardness : 500
Total Dissolved Solids: 4000

I will be draining some of the water and refilling with tap water, did not take the tap water to get tested but used the test strips and the total hardness its around 250, Will this tap water lower the CH without draining the whole pool? also should I add any chemicals to prevent the scaling after I lower the CH like ScaleTec or Beautec?

Thank You