I built a 4500 gallon pond last year made it through the winter didn’t lose any fish. I have 8 koi and 2 goldfish . I have a ton of plants in the pond a waterfall a 3 stage savio filtration system with a 35 watt uv light. I constantly clean the filter and still have murky water. I’ve tried different things to take the nitrates out have plenty of air ration just can’t get it clear