Green Pond Water

Question
I have a 1500 gallon pond, with about 100 fish. One Koi and the rest quite large goldfish, maybe half a pound each.

I have a uvlight and a filter plus pump, but this spring, the water has green bubbles over most of its surface. Put your hand into the water and it comes out pale green.  

I feed the fish with floating pellets each day.

I have tried "Green Away" a product which coagulates the algea, to no avail.

Do I have too many fish? Should I stop feeding the fish?. The uv light has just been changed.

Any advice would be appreciated.  Thank you

Roger hancock

Answer
That floating, bubbly algae may be various kinds of hair algae or even blue green algae.  It's common in ponds with a lot of nutrients and a lot of light.  If your 99 some goldfish are over a foot long, then the pond would be way overcrowded.  But, I assume they are a variety of sizes like in my pond which is 1800 gallons with 2 koi, 4 orfe, and about 30 goldfish.  Mine is crowded enough.  The UV light will only kill suspended algae and not algae growing in clumps on the surface.  I suggest using a bucket to get out what you can.  Then, be sure you have good aeration and filtration.  You want to have at least 2000 gph on your filter system.  If you have less, you can add a second filter (I have a 2600 gph pump and a 700 gph one).  You can feed the fish less.  Do you have plants?  I suggest lots of plants, good filtration, good bacteria, and maybe some barley straw.  For a full list of things to try, see htp://www.fishpondinfo.com/plants/algae2.htm

Good luck!