Yes I am pretty sure that the silica bound up in the crystalline structure of glass and sand is a different animal than the kind in suspension or cement. Here are the results of the silicate tests I took at the time of my aragocrete project:
RO water .25 PPM
tap water .5 PPM
tank water with aragocrete 2 PPM & above
note that 2 PPM is the upper limit of the test, so god knows how much silica was in that water.
I didn't test the water after yanking the aragocrete and haven't tested lately but as soon as the cement came out the diatom bloom died off. I will make some more tests soon and see for sure what was going on. I haven't given up on aragocrete yet anyway and think it is good idea.
|