tap water and chemistry questions - The Planted Tank Forum
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post #1 of 4 (permalink) Old 01-15-2013, 11:43 PM Thread Starter
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tap water and chemistry questions

I am wondering if my tap water ok to use as it is?

I took the data from the city :

The average hardness (CaCO3) is 116ppm.
If I'm correct, CaCO3 is what makes KH. And GH is made of KH + other minerals, right?
116ppm would be about 6.6DKH. And GH would be higher, but I don't see it listed in the water analysis.

Is this an acceptable value for water hardness?
Also, since I'll be using CO2 and it decreases pH, it should also decrease KH, right? So the effective KH would be lower than this?

And I've read magnesium is one important mineral to look at. I'll dose dry fertilisers including Plantex CSM+B which has some magnesium in it. Will that be enough?

I could also use my RO/DI unit, but if my tap water is acceptable as it is, it's probably useless to have it remove minerals only to add them later.

So what do you think?
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post #2 of 4 (permalink) Old 01-16-2013, 12:59 AM
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Well I'm not sure about all that, but my first thought about tap water as is, is the chlorine.

The link you provided isn't in English, so I'm not able to read chlorine levels, but yeah, usually people use tap water and a water treatment that neutralizes the chlorine to make it safe.

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post #3 of 4 (permalink) Old 01-16-2013, 01:14 AM
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Adding CO2 drops the pH, but doesn't affect the KH. Your water should work fine, as long as you use a product such as Seachem Prime to make the chlorine or chloramine safe. You can add Epsom Salts, which is MgSO4 (hydrated), for magnesium. If you dose it at about the same rate as you dose KNO3 you should have plenty of magnesium, and overdosing isn't a problem.

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post #4 of 4 (permalink) Old 01-16-2013, 01:27 AM Thread Starter
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I'll run the tap water through the sediment and carbon prefilters of the RO/DI to remove chlorine. No chloramine here.

I will only run it through the RO membrane if my KH/GH are to high. And I think I won't need the DI stage at all.

Sorry for the water analysis only being in french, I don't think it's available in english.
I think all the useful information is in the third block of the first page. The last 3 columns list min, avg and max measures.
Chlorine (Cl2) is not listed, only Chloride (Cl). Elements with ** are measured when when it exits filtration (so probably before chlorine is added). Those with * are measured in the pipes.
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