Why do we need carbonate hardness in NA? - The Planted Tank Forum
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  • 4 Post By natemcnutty
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post #1 of 5 (permalink) Old 05-12-2018, 07:23 PM Thread Starter
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Why do we need carbonate hardness in NA?

Hello, my little fans of plant aquariums from distant Russia.
I have long been engaged in aquariums and almost only plant. Me suffer long one question. Why in the natural (plant) aquarium needs carbonate hardness and what is it in principle? I understand that this is an alkaline buffer system that keeps the pH from leaking. This is understandable, but when you use soil it is not necessary, because this role performs acid buffer. Don't you? And in any case, carbonate hardness decreases with time. But here are a few questions I still can't grasp. Why in water with a carbonate hardness around 5 Amano shrimp feel much better than in the carbonate hardness to 2 and especially 0? And the same goes for epiphytic plants (anubias, eleocharis, bolbitis) - however this is only my observation. Yes, plants can adapt over time, but shrimps do not have so much time to adapt, they die quickly. Then it turns out it's not just some kind of buffer? A very important property of water that affects the livelihoods of invertebrates. I would like to clarify this issue. It's also interesting how you think there is a need to introduce additional kN+ Osmos or need only gH+? Thanks, friends.
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post #2 of 5 (permalink) Old 05-13-2018, 05:20 AM
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Hi there. The role of carbonates and bicarbonates in aquariums is not just in pH buffering, but most important, to allow bacteria in the filter to degrade ammonium. For each 1g of ammonium oxidized, bacteria needs 7g of bicarbonate. Without at least a minimum amount of carbonate hardness in the tank, bacteria will stop degrading ammonium and it will accumulate putting the living stock at risk. Also, some plants can use carbonates/bicarbonates as carbon source over CO2 (or in the absence of too much CO2).
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post #3 of 5 (permalink) Old 05-13-2018, 09:36 PM
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Shrimp need to molt regularly to survive. To do it they need calcium and a small amount of magnesium. If it is not available they cannot molt. Also if there is too much again they cannot molt. They really cannot adapt to water that is too soft or too hard.

Also the amount of GH and KH affects the amount of water that is in their bodies. When introducing them into a new tank they need time to adjust their own body chemistry to handle the different pH, GH, and mineral levels present in the new tank. Sometimes they can adjust very fast and other times it can take hours. Since there is no way to know how long it will take always assume it will take hours.

GH is a measure of the amount of calcium and magnesium in the water. If it is zero shrimp cannot molt and will die. Plants will also not grow well and that can lead to Algae issues. The calcium and magnesium can be in the form of sulfate or chloride salts or carbonates. Plants and animals prefer the sulfate and chloride salts since they dissolve easily in water. Calcium and magnesium carbonate don't dissolve easily in water and are harder for plants and animals to use.

KH measures measures carbonates which most frequently are sodium bicarbonate, potassium Bicarbonate, Calcium carbonate, and magnesium carbonate. When you have excess sulfate or chlorides in the water The PH drops. The carbonates will react with the excess sulfate and chloride forming new chloride or sulfate salts that will not affect PH. Helping to keep the PH stable.

Where does the excess sulfate and chlorides come from? They come from the GH. Plants need a lot of calcium and magnesium to grow. They also need sulfur and chlorine but only in much smaller amounts. Since the calcium and and magnesium are in the form of sulfate and Chloride salts plant growth will reduce the calcium and magnesium levels faster than sulfur and chlorine. This causes the PH to drop. If you don't have any KH in the aquarium the PH may drop low enough to harm the plants and animals in the tank.

For a healthy tank you need a stable GH, KH, and PH.
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post #4 of 5 (permalink) Old 05-14-2018, 12:15 AM
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None of my tanks are over 2 dKH (a couple are 0 dKH), but as I understand it, some very specific species require higher carbonates as it helps with osmoregulation. I believe some cichlids fall into this category.

Generally speaking, shrimp are more sensitive to GH than KH. @Surf incorrectly lumped the two together, but they are very different. Ask any caridina keeper what their KH is, and they are almost always kept with no carbonates (0 dKH).
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post #5 of 5 (permalink) Old 05-14-2018, 12:49 AM
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Originally Posted by Zuboov's View Post
Yes, plants can adapt over time, but shrimps do not have so much time to adapt, they die quickly. Then it turns out it's not just some kind of buffer? A very important property of water that affects the livelihoods of invertebrates.
GH is the most critical parameter and the one that most experienced shrimp keepers focus on for reasons listed above by surf. Most shrimp species can be kept in water that is low in carbonates/bicarbonates. Yes, even amanos and neos. Many of the shrimps I keep don't require any KH at all. There's no real worry about biological establishment in such tanks because the water is acidic enough to keep ammonia bound in NH4 form.

I agree that's it's a good idea to keep KH levels up in a low tech tank that is heavily planted, if plants are the focus of the tank. In this case, there needs to be a sufficient amount of carbonates/bicarbonates (6-8 dGH) and increased surface agitation to raise the potential of dissolved CO2. This is irrelevant in high tech tanks where you are injecting CO2. In this case a KH of 3-4 degrees is more than enough to keep the "swings" in check.
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