Tropical Fish Forum
Tropical Fish Keeping => Fish News => Topic started by: Sue on August 15, 2019, 08:17:50 AM
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It is a well known fact that water straight from the tap often has a different pH from tap water that has been allowed to stand for 24 hours. We usually ask for the pH of both when there is a problem.
In areas with acidic tap water, water companies often add something to the mains water to make it less acidic so the metal pipework does not corrode as quickly.
In areas with hard water, which usually goes with basic water, companies often add something to prevent limescale deposits in the pipework.
In both these cases, the pH will change when a sample of water is allowed to stand.
It would be interesting to see just how much this pH change can be.
I suggest that we all run a glass of tap water and test the pH immediately. Then leave it to stand for 24 hours and test again. Report the two values in this thread, together with an indication of the hardness of the water (hard, soft or middling will do) and the type of tester used.
This will give us an idea of the scale of pH change, and whether it is greater in hard or soft water.
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I have to confess that I can't do this, or at least not at the moment :-[
I have an API pH tester but not an API High Range pH tester and my freshly run tap water shows the highest colour with the test I have. Does this mean it is exactly 7.6 or somewhere above that?
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Does this mean it is exactly 7.6 or somewhere above that?
Yes. :)
Mine goes from 7.4 to 7.2
GH 7-8, KH 2-3
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My freshly run tap used to be 7.4 but it's increased over the last few years. According to my water company, my GH has increased slightly. In 2010 (in a pdf for the whole area, which I saved) they gave it as 4 dH; currently they give it as 5.6 dH
I never bothered with High Range pH because freshly run tap water was always below the highest level. It looks like I'll have to buy one now.
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I have done this test in the past, when I've been confused by my tank water values and how they differed from my tap water, because I thought I was doing something wrong to impact the tank.
Tap water pH is 7.0
After 48 hours pH is 8.4
17dH
Tests were done with the API kit.
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PH levels:
Tap water directly - 7.5 (JBL liquid-based test kit); 6.4 (JBL Easytest 6-in-1 strips) [quite a difference, I know; the water here is very soft, and I'm aware the PH is buffered, so I can only assume the former is the buffered level and somehow the strips are able to detect the 'natural' level]
Same results on each test after 24 hours
[7.4 min; 8.02 mean; 8.3 max; according to water company]
KH & GH:
Tap water directly - 1 KH (API test kit); 2 GH (Tetra test kit); >4, <7 'dH/GH; 6 KH (JBL Easytest 6-in-1 strips) [again quite a difference between test kits but the liquid-based ones are more in tune with what would be expected from the water company]
Tap water after 24 hours - 1 KH (API test kit); 1 GH (Tetra test kit); same results on test strips
[German degrees hardness = 1.86; CaCO3 = 33.16; according to water company]
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I was just about to do this test... I still will, later on so I can do the repeat after work. But it just occurred to me that the ph drop might be related to the co2 content of the water. Is there anyone out there with appropriate test kit to identify co2 levels separately to pH? I also wonder if there will be a difference if I store the water for the repeat test in the test tube so the co2 can't gas off as much...
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pH drop is one factor for changing pH. Do you have a container of some sort, even a spare beer glass ;D
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pH drop is one factor for changing pH. Do you have a container of some sort, even a spare beer glass ;D
I do have a container... but you've lost me!?!?
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Sorry, what I mean is to run some water into a glass (or whatever), then take a bit out and test it right away. Then 24 hours later, take a bit more and test it again.
Or run some water into a container with a lid, test some right away then shake the rest for half an hour. Then test again. The trouble with this method is that after shaking it for so long, your arms will ache and not be in a fit state to do the testing ;D
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Getting half an hour of shaking done with an 8 week old at home is not going to be even remotely possible, whether I have the arm strength or not!!
My tactic is to... test initially then, leave 1 sample in a sealed container and 1 sample in an unsealed container for 24 hours before testing again. Not sure if ill see any difference... but ill try it nevertheless,!