I had been ordering a much smaller bottle directly from the manufacture and spending way too much for the quantity we use. We have a 8 x4 foot pane of textured glass that has water pumped from a reservoir below and cascades down both sides. It's beautiful...but if we don't use Protec, the pump burns out from build up and leaves us with a big "window" in our lobby. I highly recommend this for any size indoor water feature.