# Reduce KH by boiling water?



## johnzhou2476 (Nov 28, 2006)

Some folks on this board are asking ways to reduce KH since we know that Low KH in general is good for plant growth. Without going the RO route, couldn't one reduce KH by boiling water or using the hot water supply line? One could use a resevoir to let the hot water cool before making any water changes.


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## billb1 (May 29, 2009)

Hi Johnzhou2476,

I believe that boiling water is only a temporary way to drop kH. Boiling drives off dissolved CO2 gas but over time, this will come back either from adding CO2 for your plants if you use it, or from the atmosphere. 

Bill


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## Philosophos (Mar 1, 2009)

Not only will it recombine, if you boiled the water without a lid then your KH will rise due to evaporation; same quantity of calcium, less volume.


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## Diana K (Dec 20, 2007)

Try it and see. 

Test:
GH (Calcium and magnesium)
KH (carbonates) 
pH
TDS (Total Dissolved Solids) 
temperature

Boil the water, then CAREFULLY pour it off, leaving the settled material at the bottom. Siphoning might be better, just keep the siphon off the bottom. 

When it reaches the same temperature as before repeat the tests. 
Let the water stand overnight, or longer, then repeat the tests again.


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## MoonFish (Feb 12, 2006)

johnzhou2476 said:


> Some folks on this board are asking ways to reduce KH since we know that Low KH in general is good for plant growth. Without going the RO route, couldn't one reduce KH by boiling water or using the hot water supply line? One could use a resevoir to let the hot water cool before making any water changes.


Maybe some of us just refuse to believe most plants can thrive in hard water?


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## johnzhou2476 (Nov 28, 2006)

Moonfish - nah, GH isn't the problem, we all know that plants grow well under various different GH condition. It's the KH that creates problem for some plants. I'll tell you, once I lowered my KH from 6-2 degree, all of my plants responded amazingly, almost overnight...


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## ashappard (Jun 3, 2006)

MoonFish said:


> Maybe some of us just refuse to believe most plants can thrive in hard water?


fair enough.
some plants do not like carbonate, some are indifferent.

dosing and uptake and gas mixing and general plant health - 
is it easier or more difficult to get good results in low KH?
my experience says its easier.
results may vary.


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