I need to adjust water in new concrete koi pond

[Evie]

We have a 200-250 gallon outdoor concrete Koi pond that was re-surfaced exactly one month ago. Our 14 fat Koi have been living in an 80 gallon Rubbermaid tank. They want to go back to their nice pond, but I want to make sure I set the water chemistry correctly and I want to make sure that the new concrete has completely leached.

After the new concrete had set, we filled the pond with plain tap water and occasionally stirred and scrubbed for a month in the cold winter weather. The water surface froze. When it thawed we poured in a gallon of muriatic acid, scrubbed some more, then drained the pond and filled it with tap water again. We let that water sit for a week, scrubbing a bit.

Now we want to replace this water with fresh tap water and start adjusting the chemistry to dechlorinate and achieve the proper pH level.

My questions are (1) has the concrete cured sufficiently so I don't have to worry about further leaching (which would upset my attempts to get the pH set correctly); and (2) what should I be adding to the tap water now to get the pH in the proper range?

 

[DrDave]

Test it, then leave it alone for a week and test again. That way you will know if it is going to change more.

 

[DoDad]

What is your ph now?

 

[Evie]

The surface of the pond is frozen now. When it thaws I will report the pH. Thanks.

 

[Evie]

Update on our concrete koi pond. First, I apologize for the double post. Overnight temperature is mostly below freezing (below 20 F last two nights) but we were able to test last week, pH is above 8.0 (as far as our test strips go). Our fish consultant at SuperPets informed us that unless the concrete is sealed, it will leach calcium forever and will need weekly monitoring and pH adjustment. This is a surprise, but perhaps should not have been, since the former pond bowl surface was something like plaster (epoxy paint?) covered by a layer of black paint. I do not want to have to monitor the pond pH, so now I need advice on the best sealing technique. Of course, comments on the advice I have been getting (from the concrete construction guy to the fish guy) are welcome. Thanks again for your help.

 

[sissy]

Isn't that a lot of fish for a small pond .I have plans to add to mine this spring as I have 12 and just found 4 more small fish that appeared from no where .well somewhere anyway didn't know they were there .just found them yesterday since we got a warm spell and pond is unfrozen .they are all black and about an inch or so long

 

[Evie]

The fish have been pretty happy for the past eight years. How can you really tell if they are happy though?

 

[DrDave]

Look for a smile on the faces.

 

[sissy]

they are healthy they are happy teach fish how to smile maybe .hmmmm

 

[Evie]

So, Doctor, do I need to seal my concrete pond?

 

[Evie]

I have attempted to attach a picture of one of our Koi, in happier days, prior to the pond leak. Is this a happy fish or what?

 

[sissy]

oh no the dreaded pond leak

I looked dr dave I can't find one smile LOL

 

[DrDave]

I have used asphalt emulsion (40 years ago, that was the way) and I have not sealed at all. Both worked for me. The key is to make sure most of the lime has leached out first.

This is why I will never do a concrete pond again. Once liners became reliable, I never looked back.

 

[sissy]

I agree with that my liner was so heavy when I got it in the pond I was under it and It really must have been a funny sight if I had neighbors .I had to adjust it for at least an hour or more from under it and then had to crawl out ,that is when I finally found out which direction to go to get out since I am only 5 / 2 and the pond is just a little over 3 feet on the deep end and I wanted to go out the other end where it is only 2 feet deep so I could get out .geeze height matters LOL