Maybe find one like 5-1-1 and mix em?
CalN is used to raise the N value and ofc calcium.
I did find this
http://www.easy-grow.co.uk/products/nutrients/raw-silica/
That seems to be the desired stuff with nothing but silica in it, unless it is a con and does not work unless combined with something else like K. I recall reading something about a type of P that is useless unless in a certain form/combination. Or was it K..
I read a bit more , ''stated'' differences is that raw silica does not increase ph (pro or con depending) but, as real downside, in raw state it is not as available to the plant like silica+K is. On the other hand it also seems safer from bonding, so they imply. Still, seems a waste to put in 50ppm of it and only have say 30ppm accessible (maybe even less?). But then again p and k etc do that similarly with the conversion rates. Not sure if the remaining raw silica in the soil would build up to a dodgy level.. it does not sound like it would come out in run off easily.