we have just installed a new water garden - about 2000 gallons. It is rock lined per Aquascape videos, has skimmer and Bio-Falls. We rinsed rocks and removed silty water. All is functioning properly. Two nights ago we had a VERY heavy rain and the water became murky. After a day, it is somewhat clearer, but the flat rocks have a good 1/4" - 1/2" of silt on them. What should I do about this? I don't want the water to be so opaque .... Thank you!