Water quality in 1 month old pond

[Steves55]

Pond is new (I have another on other side of yard)
Pond size is 3500 gallons w/ 4" bottom drain, Savio lg skimmer & UV & fill, EA Pond sieve, Savio Living pond waterfalls, Ext pump is Artesian.
Ammonia, nitrate, nitrite are at 0
PH is 8.0- same as tap water
KH is 150 ppm & GH is 300 ppm- same as tap water
Phosphates are what concerns me. It is at top of scale on test kit at .5.
I tested my tap water & that's the source. It's the same level!
Pond has 5 Koi- largest is 15", 2-12", and 2-4".
Tips? How do I deal w/ the high phospates. No fish or pond issues BTW.
In my 150 gallon salt reef tanks- I use DI water. 3500 gallons is not an option for DI! How can I lower the posphates & GH? Water changes won't help- that's the source.

[lildude]

Quote: Originally Posted by Steves55 Pond is new (I have another on other side of yard) Pond size is 3500 gallons w/ 4" bottom drain, Savio lg skimmer & UV & fill, EA Pond sieve, Savio Living pond waterfalls, Ext pump is Artesian. Ammonia, nitrate, nitrite are at 0 PH is 8.0- same as tap water KH is 150 ppm & GH is 300 ppm- same as tap water Phosphates are what concerns me. It is at top of scale on test kit at .5. I tested my tap water & that's the source. It's the same level! Pond has 5 Koi- largest is 15", 2-12", and 2-4". Tips? How do I deal w/ the high phospates. No fish or pond issues BTW. In my 150 gallon salt reef tanks- I use DI water. 3500 gallons is not an option for DI! How can I lower the posphates & GH? Water changes won't help- that's the source.

use
Phosban, or another product like that, but used for koi ponds.