At least i can continue to use my clay pot for now.i was a little worried because i just repotted few cattleyas in clay pots.
It is very rare to get mineral build up with clay but watch with Cattleyas, some species and their hybrids are very prone to fertilizer burn, I have one like this. I prefer to use clay for really top heavy plants like dendrobiums, cattleyas, and oncidium hybrids.