co2/gk/kh chart?
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Old 01-13-2013, 08:16 PM   #1
pigeonfood
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co2/gk/kh chart?


is there a chart that can somewhat read how much co2 is in me tank.
Using DIY setup.
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Old 01-13-2013, 09:46 PM   #2
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Here's a calculator:

http://www.fishfriend.com/aquarium_co2_calculator.html

As always, the output is highly dependent on the accuracy of the input. Try bumping the KH up or down one degree, and you'll see what I mean. A KH test kit only gives you results to the closest degree, and it's easy to read pH wrong by 0.2, so some error is expected.

Plus if there's non-carbonate alkaline buffers in your water, that will completely throw it off too. Though this isn't usually the case.

This is why a drop checker is preferred.
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Old 01-14-2013, 11:55 AM   #3
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Quote:
Originally Posted by DarkCobra View Post
This is why a drop checker is preferred.
Is a drop checker basically accurate no matter the KH of the tank or is it also dependent on that?
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Old 01-14-2013, 12:25 PM   #4
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Quote:
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Is a drop checker basically accurate no matter the KH of the tank or is it also dependent on that?
Since the Drop Checker solution has a known KH (typically 4dKH using RO/DI, distilled, or otherwise purified water) the results are accurate regardless of the tank water.
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Old 01-14-2013, 12:31 PM   #5
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Thanks. Nice reef tank BTW.
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Old 01-14-2013, 12:38 PM   #6
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Thanks.
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Old 01-14-2013, 01:57 PM   #7
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Quote:
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Is a drop checker basically accurate no matter the KH of the tank or is it also dependent on that?
A drop checker will react to the amount of CO2 that gases off from the water. kH will change that amount, as it affects how much CO2 you have in the water. That's why pH does not drop under a certain value depending on how high is the kH.

So, the drop checker is accurate but slow. It will show your CO2 level about 30 minutes to an hour ago. Not the current value.
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Old 01-14-2013, 02:10 PM   #8
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Quote:
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A drop checker will react to the amount of CO2 that gases off from the water. kH will change that amount, as it affects how much CO2 you have in the water. That's why pH does not drop under a certain value depending on how high is the kH.

So, the drop checker is accurate but slow. It will show your CO2 level about 30 minutes to an hour ago. Not the current value.
So are you saying that a high KH requires more CO2 in the water but the drop checker still accurately reflects that. Green is green and yellow is yellow.
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Old 01-14-2013, 09:18 PM   #9
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Quote:
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So are you saying that a high KH requires more CO2 in the water but the drop checker still accurately reflects that. Green is green and yellow is yellow.
KH has no effect on the amount of CO2 required. It only affects how much a certain amount of CO2 changes the pH. More KH, less change; less KH, more change.

A drop checker is really just a pH tester. Only CO2 can enter. Water cannot, and because the water inside always has a fixed and known KH, it always produces a predictable color change for a certain amount of CO2.
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Old 01-14-2013, 09:36 PM   #10
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KH has no effect on the amount of CO2 required. It only affects how much a certain amount of CO2 changes the pH. More KH, less change; less KH, more change.
I dont think it even does that. A 1 point drop in ph is always a 10 times increase in CO2 regardless of KH.
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Old 01-14-2013, 09:39 PM   #11
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Quote:
Originally Posted by DarkCobra View Post
KH has no effect on the amount of CO2 required. It only affects how much a certain amount of CO2 changes the pH. More KH, less change; less KH, more change.

A drop checker is really just a pH tester. Only CO2 can enter. Water cannot, and because the water inside always has a fixed and known KH, it always produces a predictable color change for a certain amount of CO2.
That explains it well. Thanks.
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Old 01-15-2013, 03:49 AM   #12
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I used an AP pH test strip and if i have 120ppm kH and 180ppm gH is that considered hard water and good for plants when using co2??
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Old 01-15-2013, 05:29 AM   #13
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To convert ppm to more familiar degrees, divide by 17.86. Which, rounded to one decimal point, gives you:

gH=10.1 (hard)
kH=6.7 (plenty high enough to keep the pH from dropping too low with CO2)
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Old 01-15-2013, 09:52 AM   #14
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Quote:
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I used an AP pH test strip and if i have 120ppm kH and 180ppm gH is that considered hard water and good for plants when using co2??
Depending on the plants. If you have soft water plants that is too much. You might want to target a kH of 3-4 dkH and gH of 6 or lower dgH.

Quote:
Originally Posted by dmagerl
I dont think it even does that. A 1 point drop in ph is always a 10 times increase in CO2 regardless of KH.
kH will determine how much CO2 stays in the water as carbonic acid. There are separate reactions when it comes to CO2.

Plants use CO2, part of it will react with water and make carbonic acid, a huge part of this acid will "decompose" further into bicarbonate giving off an Hydrogen ion thus making the pH go down. Adding bicarbonate into water will slow the carbonic acid from breaking down and cause a pH drop. More carbonic acid will form and the CO2 concentration in the water will drop. Lower kH will allow the reaction to carry on, bicarbonates further "decompose" into carbonate and another Hydrogen ion is released. Finally, carbonate itself breaks down into water and CO2.

It's hard to describe exactly how much CO2 you have in the water at any given moment. That is because the reactions that take place are pH, temperature and kH dependent. This is the reason why you want a low kH in a planted tank.
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Old 01-16-2013, 12:03 AM   #15
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This maybe a stupid question but does adding fertilizers to the water column raise gH and kH??
Reason i'm asking is because, I was going over my EI dosing using the nutrient calculator from http://calc.petalphile.com/non-mobile
and i think i may have to up the ante on my dosing I don't think i'm adding enough.
Im using the macro and micro pack from Green Leaf aquariums
the pack comes with
Micros -
Plantex CSM + B - 1 / 2 Pound
Macros -
Potassium Nitrate (KNO3) - 1 Pound
Mono Potassium Phosphate (KH2PO4) - 1 / 2 Pound
Potassium Sulfate (K2SO4) - 1 Pound
but when i got this pack i read to add about 1/8 teaspoon of each macro in 60ml distilled water and mix and dose about 1-2ml of that mixture to my tank about 1-2 times a week.
am i doing anything wrong?
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