Ok guys. Since my buffer appears to have failed, I'm going to empty the top-off resevoir and mix up a heavier batch of Agsil. I'll let it set overnight and check the pH in the morning. If it's not above 9, I'll add and mix some more before heading to work. My water level in the lower res is higher than where the float valve starts dumping anyway, so we should be ok. I'll prop it up just in case. No accidental drippage. Little bit of wasted nutes won't break the bank.
The lid is the other issue. I'm on it. Just need something hard and flat that I can cut a hole in and mount my rack to. Will probably have to wait on shipping unless I can find something at the hardware store tomorrow or Saturday.