Has anyone else in the Middle TN area had any issues with silica/silicates and ditaoms? Over the last 3-4 years I have struggled with on-going diatoms in my reef tanks and have to assume through process of elimination it's either the sand I've used or the water supply that are feeding it with silica/silicates. I have a 4 stage BRS RO/DI with only one DI cartridge that is replaced fairly regularly, but knowing silicates will not register on a standard TDS meter I'm wondering if anyone has dug into the metro water supply and if the water is unusually high in silicates? Just asking as I don't have a silicate test kit and thinking of adding an additional DI cartridge, possibly with a silica buster insert. I've also used "Oolite Aragonite Reef Sand" purchased from Petsmart (good deal when it was on sale) on both of my last two tanks. This stuff is extremely silty due to it's fine consistency but this last tank build, I rinsed the holy hell out of it multiple times and allowed it to dry for weeks before using it. I suspect that the sand may not be true "aragonite" and wouldn't be surprised to find it's high in silicates or mixed with some silica based sand. I notice the diatoms get crazy when I stir up the sand bed, but it's not due to nutrients because those have been under control, and this new sanded is not old enough to worry about being a nutrient sink. Short of changing out the sand bed (not something I want to do in a 125) I also want to make sure I'm not feeding additional silicates into the tank via all of my top off and water change RO/DI water. Thanks ya'll!