^The brief overview of water chemistry is I'm sure welcome for many readers, but so far you have not shown how this external up-stand pipe works, and what happens to the water and sediment once it overflows out of it. A photo or diagram should be available.
I have no idea about Dalton's water chemistry, his personal business practices, nor how he made his feed. All I can say is that when I spoke with him, he did not strike me as incompetent. I'm sure he had test kits, and if the water was heavily fouled, he would know how to do a water change.
Please take the time to make a diagram, or take a couple of pictures with your phone, which illustrate the function of this external up-stand pipe, and what happens to the water once it overflows out of it.