Does this seem accurate?

Brett

Brett

AC Members
Dec 23, 2004
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Jerseyville, IL
According to my test kit (tetra), I'm consistently coming up with these results in my planted 75.

ph - 7.0

kh - 2

gh - 4

My first question was going to be if it would be possible to raise the KH without affecting the PH. According to some older posts this is not possible.

Perhaps my test kit is somewhat inaccurate or vague. With a ph of 7.0 shouldn't my kh be expected to be higher than 2?

Thanks,
Brett
 
PH and its relationship to KH and/or GH levels are rather sketchy. Both KH and GH are "supposed" to increase the Ph, but do not necessarily do that apparently in all situations. In water that comes out of your tap you may have an acidic presence such as peat that will counteract the alkaline nature of GH and KH (that raises PH). If the KH and GH are also already present before anyone does anything to it, you may have levels of alkaline causing agents such as KH/GH that, while present, have to contend and compete in the PH battle with acidic agents. But if you had water with a certain PH and THEN added alkaline agents for KH or GH and the PH did not turn more alkaline...I would be stumped.

So, well it's a little complicated. And people need detailed factors supplied, and even then there are parts that I have not understood from reading certain posts/articles but have not experienced personally. So...

Well, I can't really say with any authority...

But no, with GH and KH levels that low, a PH of neutral (7.0) is not eyebrow raising at all. I would guess that your test kit is not obviously faulty. Any presence of KH would tend to raise the PH above the level of 7.0.
 
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Brett said:
My first question was going to be if it would be possible to raise the KH without affecting the PH. According to some older posts this is not possible.
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Baking soda raises my KH without raising the pH. I used it temporarily to raise mine to safe levels before I started injecting CO2.

Perhaps my test kit is somewhat inaccurate or vague. With a ph of 7.0 shouldn't my kh be expected to be higher than 2?
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Would be nice, eh? My pH is from 7.6-7.8 and my KH is 2, GH 7. Your test kit is fine.

Roan
 
RTR said:
GH has no effect on pH.

Baking soda, sodium bicarbonate, NaHCO2, will raise the KH and the pH.
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That's what I read, why didn't it raise my pH when I added it? I tested before and after. KH was 3, pH 7.6 and after KH 5, pH 7.6

I'm confused.

Roan
 
the pH KH correlation is tight enough to accurately estimate CO2 levels with. Co2 will lower Ph without effecting KH, almost nothing else will. Items like peat release natural acids which remove the KH from solution and Lower pH accordingly. so witht the use of peat we actually see the Kh reduction and the subsequent pH reduction. With co2 Kh stays constant while pH drops according to Co2 levels.

THe fluctuations from tap to tank are generally the result of elevated CO2 levels in the pipes. once we expose the water to open air the CO2 begins to equalize with natural situations and the pH increases. In some case there are fluctuations caused by unstable chemical buffers of one type or another as well. Either way your should let Tap water gass off in a shallow dish for several hours before testing, and KH should not change despite fluctuations in pH.

A KH of 2 dKH could put you at roughly 7. pH, it should be more like 7.2, but there is always some margin of error in hobbyists test kits.
 
I am glad that my test kit is working. I always thought my ph was too high for a KH of 2 dKH. Thanks for the insiteful replies. This website is an awsome resource.

The tank is a planted "community" discus tank, without CO2 injection. I guess I was just looking for a "quick fix" to increase my co2, I see I have more to learn about the relationship between co2, ph, and kh.

On this tank I do a weekly water change of 4 parts R.O. water to 1 part tap. Our water in this region is very hard. I'm going to have to try and set up an African tank some day. :)

Anyway, thanks again!
 
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Nothing will raise CO2 levels in your tank except injecting it. Raising or lowering kH or pH does not affect CO2 levels at all.
Carbon can be added by dosing Seachem's Excel however.

Len
 
I never realized that GH would not raise the PH. Interesting.
 
The confusion over GH and pH is due to the case that naturally occuring calcium and magnesium salts tend to be carbonates and bicarbonates when dissolved out of aquifers in FW, so folks associate high GH with high pH, but it is an unjustified assumption. If the plentiful Ca/Mg were from chlorides or sulfates, and there were few or no carbonates/bicarbonates present, the water would be hard (GH high) but have no buffering (low KH) and could easily crash. But I have never heard of natural waters with that profile. In tanks, anything is possible, or almost.
 
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