Join Date: Jul 2010
Location: Outside Philadelphia, PA
Could it be that the gravel had a lot of dirt in it, and it's all from that? New gravel often has a ton of fine material in it that clouds water like that, even if you wash it.
You could check easily enough. Take a glass of water, add about a teaspoon of bleach to the water in the glass, and let it sit. The bleach will kill algae and bacteria, but will not do much with particulate matter.
If you have or have access to a Diatom Filter, you might be able to filter that stuff out.