JasonLion said:If your pebble surface is less than four weeks old you could add some Jacks Magic The Blue Stuff, or some similar sequestrant that is optimized for fresh plaster/calcium. If it is more than four weeks old, then that is much less important/useful.
The key thing is to keep your PH below 8.0. Make sure you have muriatic acid on hand and test the PH at least daily till things settle down.