Sodium Ascorbate. PH neutral form of Ascorbic Acid. Ascorbic Acid will lower your PH.

Cheapest I've seen for the real stuff is 105 bucks for a 5.5lb bucket. Has all the gub blessings to boot.

One gram of the powder will destroy 1ppm of chlorine and, or, chloramines in 100 gallons of water, approximately. Best to pre mix and test tho.