I have a 3400-gal pond that's about 15 months old since enlarging it. I have 7 Koi ranging in size from 6-22", several plants, a skimmer, Ultima IV 4000-gal Bio-filter, waterfall and oxygenator, depth from 2.5-ft to 4.5ft. I backwash my filter twice/week. The water has been very clear up until a few days ago and now the water has become so murky that I can barely see my fish unless they come up to the surface to feed, I have some string algae, but it's not bad, due to an umbrella that shades about 1/2 of the pond. I've tested the water and it's within normal range for everything, yet I'm stumped as to why the water has gotten so murky all of a sudden. I just added some barley extract, maybe that might help. What am I missing, any suggestions?
--Eric
--Eric