Related question. Our new ponds, including the one I dug last year have a glacial, Caribbean, blueish water color that is somewhat transparent, with maybe a 2-3 feet of visibility, maybe even greater. They have red and grey clay bottoms and pretty much do not leak at all. Is the blue water color just low fertility, or also likely due to suspended grey clay? In my previous two ponds this color disappeared over time, maybe due to increased fertility and influx of plants and aquatic life? Actually, looks really pretty while it lasts.