need to lower pH - big time in a hurry.

[BCReefer]

I need to lower my pH. I added Kalk last night and when I got home my Xenia seemed to have crashed big time. It has grown tremendously over the past 6 months from a single shoot to about 6 – 7 big pieces.

I started checking my water parameters and 1st thing I check was my Ph and it read over 9.0. I have been adding Kalk for the past 3 months and this has never happened before. I did add a little more than normal but only a ½ teaspoon more.

I did a 20% water change and I will test again in an hour. Stupid me I did not test for alk, nitrates etc.

The rest of the clams still look good and the fish look OK. I have turned off the light and I will maybe do another water change around 10:00. at that time I will test the rest.

Can anyone make a suggestion about how I can lower my pH?

Thanks
Patrick