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#### FenderOffset238

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So I have started up a new planted tank using RO water, and I know you must add back trace elements/buffers to the water.... but I have no clue what im measuring when it come to water hardness.

Im looking to set the parameters of the tank around: gH 3-5 with kH 2
But the test I have measures the GH in "mg/l CACO3" and KH in mg/l
How do I convert this to get a regular GH or KH reading?

My water is yet far (from the test):
GH - 60 mg/l
KH - 20 mg/l

Can anyone shine light on this chemistry confusion... I just cant seem to comprehend what means what, and I've done my share of reading too....

#### deleted_user_17

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Hiya

I am new to RO water too and having to get my head around this stuff too.

mg/l is equal to ppm

So your
GH - 60 mg/l can also be read as 60 ppm
KH - 20 mg/l can also be read as 20 ppm

To get the degrees of hardness dH, you divide by 17.9.

So this means that

GH - 60 mg/l can also be read as 60 ppm which when divided by 17.9 = 3.35 dH
KH - 20 mg/l can also be read as 20 ppm which when divided by 17.9 = 1.12 dH

This is how I understand things, hopefully this can be confirmed by someone much more experienced than me...

#### FenderOffset238

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Hiya

I am new to RO water too and having to get my head around this stuff too.

mg/l is equal to ppm

So your
GH - 60 mg/l can also be read as 60 ppm
KH - 20 mg/l can also be read as 20 ppm

To get the degrees of hardness dH, you divide by 17.9.

So this means that

GH - 60 mg/l can also be read as 60 ppm which when divided by 17.9 = 3.35 dH
KH - 20 mg/l can also be read as 20 ppm which when divided by 17.9 = 1.12 dH

This is how I understand things, hopefully this can be confirmed by someone much more experienced than me...
Wow! I hope your right, cuz then i'm just about on track!

With a KH as low as this, is there any good way to handle the pH if you want to inject CO2? When I put in my diffuser around 1.5 bpm, my pH sinks.... but if worst comes to worst I can do with out the CO2...

#### deleted_user_17

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I am keeping a shrimp tank and my tap water has nitrite in it so that's why I am going RO - so I haven't got a clue about CO2 injection! Wait for confirmation on my input, it could be very wrong!

#### FenderOffset238

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Jedi_Pizza - In the research I've done since, the info you supplied me seems to be correct. Just incase you were doubting yourself.

#### dmagerl

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With a KH as low as this, is there any good way to handle the pH if you want to inject CO2? When I put in my diffuser around 1.5 bpm, my pH sinks.... but if worst comes to worst I can do with out the CO2...
I dont understand what you're getting at. Regardless of the KH, pH will always drop the same amount for the same amount of CO2.

A 1 point pH drop always indicates a 10 times increase in CO2 regardless of the KH value if all other variables remain constant.

Unless you're just saying a low KH equates to a low pH and CO2 will lower it more.

#### deleted_user_17

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Jedi_Pizza - In the research I've done since, the info you supplied me seems to be correct. Just incase you were doubting yourself.
Nice one

#### Diana

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Get the KH up just a bit, and the pH will probably be more stable, though it will still show a drop. Get it closer to the 2 degrees (35 ppm) that you were aiming for.

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