How Can I Lower KH Naturally? - The Planted Tank Forum
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post #1 of 6 (permalink) Old 02-25-2016, 12:59 PM Thread Starter
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How Can I Lower KH Naturally?

The title just about says it all... I have a newly cycled 7 gallon and I am really excited about adding 6 sparkling gouramis (2 males and 4 females) but I checked the KH and it is so low my API liquid test kit can barely read it. It is supposed to turn from blue to yellow after adding a certain number of liquid, and mine is turning a greenish color (in between blue and yellow ) and with the second drop it is already a yellow color... I am afraid this is too low for the gouramis, and that it will make my tanks pH really unstable. So, how do I raise the KH without having to buy any scary chemicals ? Or does the low KH really even matter? Will the gouramis be bothered by such soft water? Even if they aren't, won't the pH fluctuate?

Any advice, tips or experiences are welcome !
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post #2 of 6 (permalink) Old 02-25-2016, 03:48 PM
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Baking soda will do the trick. Not scary at all unless you combine it with vinegar!

However, I'd say it's probably nicer to have too little kH than too much.


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post #3 of 6 (permalink) Old 02-25-2016, 05:53 PM
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Originally Posted by Iwagumist View Post
The title just about says it all...
Title says the opposite of what is asked in the thread haha

Baking soda will raise KH and pH, but adjust slowly if using this method (especially if fish are in dosed tank).
Crushed corals or Crushed Oyster shells are another option.
There should be Calcium Carbonate powders as well.
And there are commercial products to raise KH.

Lower KH water does have less buffering capacity, but it only really is worrysome if you have many contributing factors that would make the water more acidic or alkaline. Not really a big worry if you do frequent water changes (with the proper minerals).

Are you injecting co2? Heavily planted and/or with lots of fast growers? Fish bioload should be low and so the acids from that shouldn't be much of a factor.

According to
Tropical Fish for Freshwater Aquariums: Sparkling Gourami
it says the KH should be between 4-8 dKH. So it wouldn't hurt to raise the KH (still keep in mind PH, GH). Not sure how accurate the site's care specs are though.

I'd say it's probably nicer to have a little more KH than too little.

What are your other water parameters? (pH, GH, temp)
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post #4 of 6 (permalink) Old 02-25-2016, 06:26 PM
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The website mentioned above is a business, it's an LFS online, nothing more. The pH listed there is too high. There's at least 1 website that lists pH for Trichopsis pumila as low as 5. Mine is currently well below that and the pumila in it are thriving. From a business perspective recommending a pH closer to neutral than it actual should be is advantageous.

There's no such thing as water too soft for any Gourami species. If we want to buffer the water to protect against fluctuations we simply add IAL (in the Tropics) or fresh peat moss (in temperate climates). Wrap a few handfuls (for a tank of <10g) of peat moss in a nylon sock, tie it closed, drop in water. That's all the buffering we need. As the weeks pass it will gradually sink. Once it hits bottom replace the saturated peat with fresh peat.

Baking soda, crushed coral/oyster, or calcium are all a bad move for Gourami. Breeding fish is an indication of optimal conditions. Show me a tank where Gourami have been bred using those aforementioned products and I'll retract my statement. Peace.
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post #5 of 6 (permalink) Old 02-25-2016, 09:29 PM Thread Starter
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Originally Posted by jaliberti View Post
There's no such thing as water too soft for any Gourami species
So I don't need to raise the KH even if it is almost unreadable on the test? Won't low KH cause pH swings?

My pH is 6.8 and my GH is around 4.
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post #6 of 6 (permalink) Old 02-26-2016, 12:23 AM
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pH is controlled by other things when the KH is so low.
If you add CO2, or have peat moss or driftwood in the tank, then these will tend to keep the pH low.
If you have limestone and related minerals (substrate, pebbles, rock) then these will raise GH, KH and this will raise the pH.
Other materials can raise or lower the pH, such as sodium hydroxide (raises pH, added by some water companies) and the materials in the various pH Up and pH Down types of products.

Best to stay away from the whole mess, if the water you have is OK for the fish, and it looks like yours is great.

Trichopsis vittata ? Croaking gourami (Trichopus striatus, Trichopsis harrisi) ? Seriously Fish

The 'Hardness' is GH, not KH.

The range of pH goes down to 5, and you are only going to get that low is the KH is pretty much zero.

If you still want to raise the KH then you could try a little pinch of potassium bicarbonate.

In the mean time, beware of the dreaded chemical Dihydrogen Monoxide.
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