Found this on this website..this is the only product I have found that says it will raise Ph but not raise alkalinity as well so thought I would share since I havent seen it mentioned in here anywhere...this would beat lowering both if TA was high then having to try an aerate in order to raise the ph alone.
from the website: [Our Easy pH is the ONLY product available which will increase pH without any significant increase in Total Alkalinity (TA). If you have the perplexing scenario of low spa pH with normal or high TA, this amazing formulation can solve the problem, and protect your valuable equipment from the damage and corrosion that low pH will cause. So innovative, it's been granted a U.S patent.
Product notes: Easy pH has 2.5 times the pH raising power of soda ash (sodium carbonate) so the six ounce package is equal in pH-raising potential to a full pound of pH up, without that product's effect on alkalinity. A little goes a long way in your hot tub! Instructions Included. Shelf life: indefinite - store in a cool, dry location.]
6 oz. Package
http://www.spadepot.com/shop/Easy-pH--- ... 3C634.aspx