Anyone used these? I have a 9.5 acre pond with 4' of average depth. 7 years old and still suspended clays with visibility from 6" - 12". Comparing pricing versus purchasing liquid alum and spraying myself. I like the simplicity of the logs placed above each of my 4 diffuser stations. They quoted me $84 per log (not including shipping) and said I would need 38 of them - 1 per acre foot of water. Almost $4K...steep!