What are your calcium levels at?
Have a look at Tropic Marin Alka Balance.
"To safely reduce alkalinity while simultaneously increasing the calcium level"
http://www.tropic-marin.com/web/english/homepage.html
We have this product in stock if you need it.
The only other alternative would be to do a large water change with a salt that is low in alk (Tropic Marin Pro Reef).