Hi hooksbob....sometime back I tried a slab of rockwool cubes from the hydro store. The directions said to pre-treat for the high PH by adding some lemon juice to water and soaking them in it 1st, before using. They gave the target range of 5.5 ph.
Of course, I did the 'guy thing' and tried using them without reading the directions. Nothing sprouted and I still have about a half of a slab that I didn't use.

I now use oasis horti-cubes, with great success. I just drop the seed in and add water....no pre-treating. Doesn't get easier then that.
http://www.hydro-gardens.com/germinate.htm#oasiscubes