Is there any way to PREVENT the white stains. Or algae buildup on the top glass?
Not to hi-jack, might be relevant to the OP. But I noticed my staining has increased since adding a bubble-disk, and algae growth right above it has increased approximately 847.3% (number may not be entirely accurate...)
I second the recommendation for CLR. It works great and has other household uses. People run it through coffee makers to clear out deposits, for example.