powder "pH Down" ... add it where?

[gregugadawg]

fill a bucket with water then add chemical then add directly to pool, you don't want any form of acid solution running directly through your equipment

[Watermom]

I wouldn't add anything until you post some water testing results for someone here to take a look at. The best way to mess up a new pool or any pool for that matter, is to blindly add a bunch of stuff that you may or may not need. Also, get a test kit that uses drops instead of teststrips.