How to lower KH and keep it there

[baloutang]

Hi,

My KH is rather high on the Salifert test it's upwards of 22. I have a 150 gal and I did a 35gal water change, but still the KH is high. Do I need to do another water change to keep lowering it?


Thanks,
Dave

 

[Reefer Steve]

Club soda/Selzter water should do the trick. Also adding regular RO/DI for top off will help too. Water changes cant hurt. Check some of those articles out. I'm sure Randy will give you a much more comprehensive answer!

 

[bertoni]

Seltzer water won't change the alkalinity, but it will drop pH. Usually, alkalinity will drop on its own fairly rapidly, if additions are stopped. If any animals are showing signs of problems, water changes should help, and are the only palatable solution to the problem:

http://www.advancedaquarist.com/issues/nov2002/chem.htm

 

[Reefer Steve]

It will only lower Ph? Thats good to know. How does it impact just Ph and not Alk?

 

[David Grigor]

What additives have you used or had used to cause DKH of 22 ? The KH reading may be in error so I'd be cautious of anything to drastic. I'd for sure verify at least against freshly mixed SW to be sure your test is working.

 

[bertoni]

Seltzer water inserts CO2 into the water column, which hydrates to form carbonic acid, thus lowering the pH. The carbonic acid adds one unit of alkalinity along with the H+ released forming the aicd. There are some articles that go over the equations.

 

[baloutang]

Thanks for all the info everyone! I have plenty of reading to do. The KH was driven up I think because of my calcium reactor, although it had been running fine for the past 2 months without issue. That is the only thing I can think of that did it.
Regarding the test kit, it tested fine with a batch of cured salt water and it had a more acceptable reading of 13. I use RO/DI water to top off every few days as well.

 

[bertoni]

pH buffers will run up the alkalinity as well, if they've been used.

 

[Randy Holmes-Farley]

If the tank alkalinity is too high, and you are not adding buffers, just reduce the CO2 addition rate to the reactor