Head scratching ?

[j.w]

Hi All
Pond is approx 18x10 feet wide and Depth is 3 foot deep

Ok so now that is 4050 gallons, a lot bigger than you said before up top in your 1st post.

 

[Nige]

Did you check the pH in early morning and just before dark?

Do you have a KH test?

Hi
I live in a soft water area so should be ok

 

[WaterGardener]

Actually, I don't think that is true. Your KH is more likely to be too low with soft water, allowing your pH to fluctuate.

Also ponds are constantly changing and the water is not necessarily the same today as it was last week, last month or last year. Without testing you are only guessing.