What’s the best way to lower alkalinity in freshwater tank

[HollyJo]

Good morning! I have a 55 gallon tank with 7 fish plus one small pleco. I have 1 butterfly koi, 3 regular koi and 2 Sarasa comets and a shubunkin goldfish. Koi are getting on larger side and are about 4-6” and comets are maybe 3” size. Please no shaming for koi in aquarium- I dug a 4000 gallon pond last fall they will be transitioning to in a few months when the snow is gone 😁. I have been doing water changes every week but recently have been having to do them every couple of days. I have city water with a water softener unit. No chlorine. My large white butterfly koi gets pink color on her tail. I checked the water with test strips and the water is very alkaline. How do I fix that? I did add easy balance to it after the water change yesterday afternoon and that did not change anything. I’ve attached a couple pictures of what I used and one of the pink in her tail. 
 

thanks for your help! 

 

Edited February 18, 2022 by HollyJo
Sarasa commet auto correct to Sara’s and took better pic of white koi

[Colu]

The reddening of the tail can because by ammonia have for check for it I have kept my comet for over 12 years I have never had any issues related to pH your more likely to have problems trying to alter your pH with chemical water treatments also  do you use a water dechlorinator like prime when doing water changes at certain times of the year they flush the pipes with high levels of chloramines unless your testing before every water change you could miss it that can cause reddening

[HollyJo]

Thank you Corey for the reply. I have not tried prime. I don’t regularly use anything in the water for treatments but tried the easy balance because I had it on hand. It didn’t change anything when I rechecked with test strip this morning. I talked to the city employee that handles the water maintenance and he said they do not use any chlorine. They did years ago but have had all new water lines put in about 5 years ago. I find it strange that I only have problems with ph in this particular aquarium. I have 7 total tanks and this is the only one that gives me problems and it has the least amount of fish in it. I feed one time daily in the evenings. For filtration I have 2 Aqua-tech filters that hang on the back of the tank and are each for 40-60 gallons. With koi I was going for more filtration. I change the 8 cartridges biweekly. When I tested for ammonia with the test strips the water tested perfect so I’m at a loss of what to do to lower the alkalinity/ph. 
 

thank you,

holly b

[Colu]

Have you tested the tap water for pH and kH if you leave it in a bucket with an air stone for 24hr you will get a more accurate reading for your pH if your tap water has a high kH and pH doing more water changes will raise your pH

Edited February 19, 2022 by Colu

[HollyJo]

I have not. I had the water company that I rent my softener from come and test and they said it was 7.0. I’ll try the air stone and bucket. Thank you for the recommendation!

 

[Patrick_G]

How high is the PH?  If it’s not crazy high it might not be an issue, but it is interesting that it’s getting higher in the tank as opposed to the other way around. Since it’s a short term situation you may be able to control it by doing daily water changes. 

[Mmiller2001]

Lowering KH will lower alkalinity and it's as simple as adding 0dKH water to the water you are using.