hoppycalif

I found a cheap source of calcium carbonate on Amazon, so I want to see if adding calcium and carbonates to the water will improve plant growth, when STS substrate has stripped most of the original calcium and carbonate from the water. I added one teaspoon of CaCO3 to the water on the left side tank, raising the KH from 1 dKH or less to 3 dKH. The effect on GH was much less, but I'm still testing GH to be sure of that.

My expectation is that the increased carbonate will increase the stem plant growth. No CO2 is being added, so there is likely less than 3 ppm of CO2, so the added carbonate may help stem plants.

Each tank has essentially identical plantings.

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mistergreen

How much pH was raised?

hoppycalif

Tank without CaCO3 pH is 6.0 or a bit less. With the CaCO3 pH is 7.2.

GH, with CaCO3 is 5 dGH. Without CaCO3 is 3 dGH.

mistergreen

Wow, a whole 1.2

GadgetGirl

Is calcium carbonate a substitute for baking soda? I'm assuming to eliminate the sodium in baking soda (sodium bicarb).

hoppycalif

Sodium bicarbonate adds sodium to the water, which isn't bad, but if you also want to add calcium I figured that adding calcium carbonate might be interesting. I know it may not work well, since I think carbonates in water are always bicarbonates, so a chemical reaction has to occur when you add calcium carbonate, and I'm not sure what the reaction is. I assume it gets hydrogen from the water, and the leftover oxygen joins the calcium to form calcium oxide. (You may recognize that I am not a chemist.)

mistergreen

I think this is what you mean

CaCO3 + H2CO3 ↔ Ca(HCO3)2 ↔ Ca2 + 2 CO2 + 2 OH

hoppycalif

When I added the calcium carbonate into the water the water became very milky, especially when I stirred it up a bit. Over night it cleared up, but a few white clumps were on the substrate. I stirred them a bit and the water became a little milky, but quickly cleared up.

I just googled this subject and it says that calcium carbonate will not dissolve in water! To say I am confused would be an understatement.

mistergreen

CaCO3 will dissolve only in certain conditions like the formula above or with other acids. Your water was 6.0 so it had some acid in it.

hoppycalif

Thank you!! Now it makes some sense.