Kh and Gh - The Planted Tank Forum
  • 2 Post By rzn7z7
  • 2 Post By madcrafted
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post #1 of 9 (permalink) Old 05-10-2018, 10:54 PM Thread Starter
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Kh and Gh

Hey y'all,

So I'm learning (the hard way) how to do a planted tank. I have an RO system because my tap water is terrible. Fish are doing great -- plants are not! And as I'm learning more, I realize Gh and Kh are important for my fish too.

I found a Gh stabilizer (Seachem Equilibrium) to handle the general hardness but I've read mixed reviews about Kh. Some say add baking soda and some say to avoid it. I don't want to add coral to my filter if I can avoid it because I can't control the amount. Is there anything that works for Kh? I found Calcium Carbonate but then I heard you need Bicarbonate...

I'm confused! Any help would be appreciated! <3
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post #2 of 9 (permalink) Old 05-11-2018, 12:36 AM
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Sodium bicarbonate (baking soda) is inexpensive and may be used to raise KH, but it will introduce sodium into your tank and for that reason some people (including myself) avoid it. Alternatively you can use potassium carbonate or (what I use) potassium bicarbonate

I've never used calcium carbonate
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post #3 of 9 (permalink) Old 05-11-2018, 12:39 AM
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Nothing wrong with using baking soda. The amount of sodium isn't going to kill your plants or harm livestock. You only need to raise KH a few degrees at most. You could always use potassium bicarbonate too. Either is fine, or use a mix of both. Crushed coral (aragonite), oyster shell grit, egg shells, etc, are all forms of calcium carbonate that will raise your KH. Certain stones like seirya also leech calcium carbonate. How much and how quickly will depend on how acidic your water is and how frequently you change out the water. It's fine to use various forms of calcium carbonate for long term buffering but if you need a quick boost... arm and hammer is your friend.
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post #4 of 9 (permalink) Old 05-11-2018, 01:26 AM
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Here is a good introduction into the subject
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post #5 of 9 (permalink) Old 05-12-2018, 09:19 PM Thread Starter
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Thanks, y'all!

I'll look into the potassium bicarbonate for the long term and use the baking soda for now. I found calcium carbonate on Amazon and ordered some of that. You guys are the best
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post #6 of 9 (permalink) Old 05-13-2018, 05:42 AM
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Calcium carbonate is very insoluble, you will find a hard time to dissolve it completely into your water. You can use sodium bicarbonate, sodium isnt an issue in such amounts needed to raise kH to a few degrees. For 2 °dKH for instance, you will add only 16.4 ppm of sodium. Sodium becomes a problem over 100 ppm.
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post #7 of 9 (permalink) Old 05-13-2018, 06:30 AM
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I would suggest a substrate to keep ur kh. I've always had problems adjusting kh every time you perform a water change because you'll have to measure it Just a bit annoying imo. Crush coral, oyster as stated above +1
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post #8 of 9 (permalink) Old 05-18-2018, 09:17 PM Thread Starter
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OVT, this link is AWESOME. Thank you!

Bump: OVT, this link is AWESOME. Thank you!
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post #9 of 9 (permalink) Old 05-18-2018, 09:32 PM
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I agree with @madcrafted , sodium bicarbonate works fine. Many times, people in this hobby tend to blame fertilizers and parameters for the lack of maintenance given to aquariums. If I think about it, pretty much every nutrient was blamed for problems with plants over the last 30 years.

Good that being said, check the requirements of the fish /shrimp. They will dictate what KH and GH you need. When CO2 is good plants do not care about 0 KH, but for peace of mind and beginners most keep a KH of 3. GH of 6 and above should be good enough for plants and the large majority of fish in the hobby.

Carbonate will be converted to bicarbonate at the normal pH range for aquariums.

On hiatus till later this year
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