Raising KH - The Planted Tank Forum
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post #1 of 6 (permalink) Old 01-12-2007, 03:47 AM Thread Starter
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Raising KH

I've been thinking about this for a little while now and recently JenthePlantGeek hit home with something she said in another thread about my PH being quite low. At that time it was around 6.9. My PH generally swings from 7.5 in the morning (I turn off my CO2 at night) to about 6.9-7.1 in the evening. My KH is always at 6. This gives me a CO2 reading of anywhere from 7 ppm in the morning to 20+ ppm in the evening.

What I've been thinking of doing is adding baking soda to my 108 gallon tank to raise the KH to 7 or preferrably 8. This should allow me to lower my BPS from 4 to 2 while keeping my PH above 7 at all times and maintaining a satisfactory CO2 level. Granted, I would have to run my CO2 at night then but whether I'm running 4 BPS for 12 hours or 2 BPS for 24 hours it equals the same amount of CO2 being used.

Here is my question: if I raise my KH by adding baking soda does my CO2 level raise with it as the charts would suggest? I just can't imagine the two (baking soda and CO2) maintain such a close relationship.

My applogies if this is a poor question.
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post #2 of 6 (permalink) Old 01-12-2007, 04:24 AM
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When you raise the kH the pH also rises. Look at the chart. Find the area where there is 2-3 ppm of CO2. That's the normal amount one would find in water. Notice how as the kH goes up so does the pH.

The ONLY thing that adds CO2 to your water is CO2.
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post #3 of 6 (permalink) Old 01-12-2007, 04:29 AM
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A 6.9 pH is not low at all. It is virtually neutral. Low is something below 5 or maybe 5.5. A 6 dKH alkalinity reading is a perfectly good reading. Once you start adding baking soda, shooting for some specific KH, you are trapped into monitoring and adjusting one more parameter to accomplish essentially nothing. I used to do that, but tried just ignoring KH and haven't regretted it at all.

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post #4 of 6 (permalink) Old 01-12-2007, 04:35 AM Thread Starter
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Can't believe I missed that on the chart. I guess it was a silly question after all. As the saying goes, alls well that ends well, and that will be the end of my thoughts on raising the KH of my tank.

Thanks again.
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post #5 of 6 (permalink) Old 01-14-2007, 01:11 AM
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Yeah, and your plants will generally do better with as low of KH as possible. Some add peat to bring down the pH/KH etc.

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post #6 of 6 (permalink) Old 01-15-2007, 04:39 AM
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when you add co2, i know the ph goes down because co2 is an acid... but does the KH go up?

my KH is always 2 degrees. So when i want to check my CO2, I just check my PH... it's quick and easy.
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