constant 9 pH

[santosa]

I inherited a mucky, algae-filled, lined, 9000 gallon hole in the ground with hundreds of goldfish 5 years ago.
Because of proper filtration, aeration, uv lights & more sweat and sorrow than I care to remember it is a thing of beauty now. Koi have thrived BUT last week I had two floaters and I don't know why. Looked and acted perfectly healthy, no marks or other unusual signs. Nitrites, ammonia normal. That was four days ago and all looks okay but I'm worried. Any thoughts?
You should know that my pH has always tested at 9 with the first drop in the tube. Never been any different in am or pm, sunny or cloudy. Have tried different test bottles. The water that I fill with tests at 7 but the pond water (which was totally drained last year) is consistently 9. Water lillys and irises do well, but water hyacinth roots turn black rather quickly.
I suspect this is sitting on limestone, but wouldn't it have leached out after 10 years or so.
Such a mystery. I guess there isn't much I can do but I would love to know other's thoughts on this. Thanks so much.

 

[DoDad]

Do you test your water?
If so what are your kh test results?

 

[santosa]

Actually I just purchased a kit but it is for pool and spa not ponds. I've been wondering if I can use that??? Thanks for your reply.

 

[DoDad]

I don;t see why you couldn't use it if all the test are there.

 

[santosa]

I remember reading about salt and buffering capacity but haven't wanted to go there. I guess it's time. - BTW, I can create lather with soap and water from the pond. I appreciate your help - no one around here knows a thing about ponds.

 

[DoDad]

test your Carbonate Hardness (gh)
and let me know what it is.

 

[santosa]

I see you're from the Pacific Northwest. I'm in Friday Harbor and some things are a tad difficult to get. I ended up with a Culligan Home Water Test Kit and do not know if it tests Carbonate or General Hardness. I can tell you that what came up on the test strip does not match anything they have on their Hardness chart. It leans towards green rather than blue which would indicate no hardness at all. pH also is not represented on the color chart. BUT Alkalinity is 240 ppm...Tried calling customer service but closed now. Where do I go from here.??