Uv filter size

[pjtaxi]

We have a 10000 gal pond and use the irrigation water from another pond to keep the koi pond full. The supply water pond has algae. So my question is is the supply water is from a hose to the fill switch how large of o Uv light do I need? Water to fill probably only runs through hose maybe 50 gallons a day. Thanks for any info

[UnkleTim]

I use a 120 watt sterilizer and also am at 10,000 gallons