Question
Hi,
I have a closed, two pond system on the slope of a hill. The upper pond is about 25'x12'x3.5' and is connected to the lower pond (25'x15'x4') with a brook. I have a skimmer in the lower pond and a filter in the upper that empties into a waterfall. The circulation is driven by a 900 gpm pump.

This past weekend we had a considerable amount of rain and a considerable amount of silty and dirty water from an adjacent construction site was washed into both of the ponds. I have since dug some ditches to prevent future contamination from this site but now I have extremely chalky water. I turned my pump off when the problem first occurred so not much of this water was circulated through my filters. Am I faced with emptying both ponds and refilling with clean water?

Answer
If it's just dirt that got in, it should be ok.  If the dirt has a lot of nutrients, expect an algae bloom though.  To clear up the dirt, you can simply let it settle over time or add a polymer coagulant like AccuClear by Aquarium Pharmaceuticals (a bit expensive for such a nice big pond like yours though) which will clump the dirt and allow the filters to remove it easier.  You can add temporary extra filter pads/floss/sponges into the beginning of the filter and clean them daily to remove the dirt.  I would start your pump going again.  As long as no toxins were added, the pond can take dirt just as it would in nature.  Dirt gets in my ponds all the time from rain and from the plant pots.  Good luck!

Robyn
fishpondinfo.com