# How To Deal w/Low Kh Water



## Hoppy (Dec 24, 2005)

If you use twice as much tank water in the test tube for KH, each drop will represent .5 dKH, which lets you measure it more accurately (assuming your test kit is accurate in the first place, but without calibrating it you can't be sure). As long as you have more than 1 dKH you shouldn't have any problems due to low KH. It does mean the when you add CO2 the pH will drop as low as 5.5 or 6.0, but that isn't a problem either.

If you decide to adjust the KH, just add baking soda, a little at a time, measuring the KH a half hour or so after adding the baking soda. It takes a surprising amount to raise the KH by 1 dKH. It would be best, in my opinion, to not raise it beyond 2 dKH, so water changes won't result in big KH changes.


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## Franzi (Dec 7, 2009)

My tap water is also about 1KH/7.2PH) out of the tap. I like to keep it between 4 and 5KH by adding a heaping quarter teaspoon per 5 gallons of water. I change 30 gallons at a time, so what I do is dump 6 heaps of baking soda in to a 1 liter bottle, fill it up with water, shake/dissolve, and as I fill the tank back up using a python hose, I slowly pour the baking soda water in to the tank so that the bottle is empty as the tank is just about full. I learned the hard way that dumping a heavily concentrated baking soda solution directly in to the tank is not good.

I like doing this before the pressurized CO2 turns on when the lights are off. That way the PH is back up to about 7.2 since all the CO2 gassed out overnight. Once the CO2 turns on, the PH slowly comes down to 6.6...right where I like it, which should be in the neighborhood of 30ppm CO2.

That's just my experience, hope it helps.


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## barbarossa4122 (Jan 16, 2010)

http://dataguru.org/misc/aquarium/C...da+(Teaspoons)=0.00&SKH=3&EKH=6&pHChange=0.00

Calculate baking soda needed to raise KH by a specified amount.


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## Hoppy (Dec 24, 2005)

I think we need to understand that just because we like it when our KH is 6 dKH, or our pH is 6.8, or our GH is 5 dGH, doesn't mean that the plants or fish prefer any of those, or any other numbers. The plants and fish are by far easier to satisfy with pH, KH and GH than we are. Does that tell you anything?


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## t0p_sh0tta (Jan 24, 2008)

Well, for the OP why do you want to raise the Kh?

I too have a kH somewhere between 0-1 and have never had an issue.


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## Tyger (Dec 9, 2010)

*Hmmm...*

RESULTS (first): One of the best things about forums is the ability to benefit from collective wisdom. I added a total of 1 tspn of baking soda which resulted in 3-drops to color change suggesting moved from approx 1 KH to approx 3 KH (with the same uncalibrated kit) which is sufficient for myself.

As to the why...

With regard to raising KH, I am new to planted tanks and was concerned about possible pH instability (based on what I was reading). Given I was getting instant color change, I was concerned my KH was closer to 0 than 1 and, again based on reading, was concerned given radical pH instability noted in 0 to near 0 KH situations. In addition, I had read that baking soda can be overdone and could cause problems. It was my hope to increase KH value to 2-4 which happened after 2 level 1/2 tspn doses of baking soda. Of course, as I am new, I did not want to just add baking soda because I read somewhere on the internet it was a good idea, see my tank go wonky, and write for help here after the fact (lol). I'm the kinda' person who will plead ignorance ahead of time, learn from folks who know, and be happy with the results (i.e., to be thoughtful and patient).

Hoppy, offered general wisdom: "I think we need to understand that just because we like it when our KH is 6 dKH, or our pH is 6.8, or our GH is 5 dGH, doesn't mean that the plants or fish prefer any of those, or any other numbers. The plants and fish are by far easier to satisfy with pH, KH and GH than we are. Does that tell you anything?" which is helpful to me as I am not totally certain what aspects of water chemistry are more flexiable/guidelines (fish and plants tolerate a wider range) and what aspects are fairly hard and fast. 

And, finally, I was wondering what I might expect in terms of water chemistry changes as I consider adding CO2 System.

It is good, however, to know that you have KH between 0-1 and never had an issue which seems inline with quoted comment by Hoppy. Again, I think for the addition of 1 tspn getting 2-4 KH (vs 0-1 KH) with a 0.2 pH bump is for me, less my fish and plants, a comfort zone thing given what I was reading about 0-1 KH and pH instability (though having learned a little more... understand there is more flexibility here than I might have thought).

~Tyger~


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## t0p_sh0tta (Jan 24, 2008)

I started out with South American fish that come from more acidic waters. I set up my fist heavily planted tank with Aquasoil and a full CO2 outfit in hopes of really driving my pH down. I tested, tested and tested. Test strips, pH meters, calibrations, etc. I found that the more I left well enough alone, the better everything has been doing. 

I've been able to successfully grow every plant that I've come across, and my fish breed like rabbits. Last I checked (well over a year ago), my pH was in the low 6s after 3-4hrs of CO2 injection. You'd be amazed at how well fish adapt to different conditions as long as they're introduced slowly and parameters are kept somewhat stable.


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