You replaced approximately 4488 gallons, but ..... some of the water replaced on the second and third dumps would have been some of the new water. Whether or not water replacement will lower your pH depends on the pH of your fill water.

Get a cheap OTO (yellow drops) / phenol test kit, or if available at YOUR Walmart (check availability), get the HTH 6-way DROPS test kit, which is compatible with the Taylor K2006. Either one of these will help you in the meantime until you get the good kit. (If it is available, get the HTH 6-Way as it can measure CYA. The OTO/Phenol Red kit cannot but is better than nothing.

EDIT: Looks like Jan was posting while I was typing. The way I figured out how much water you replaced was converting all your measurements into inches 40ft = 480 inches, 18ft = 216 inches. So, you replaced a volume of 480x216x10 = 1,036,800 cubic inches. A gallon is 231 cubic inches so I divided that number by 231 and got 4,488 gallons. But, like I said, each time you did an additional partial drain, you weren't just dumping old water but also some of the new water.