# KH dropping



## DLeDeaux (Dec 27, 2002)

Any CO2 being put into the water? You should see a corresponding drop in pH, but if understand correctly, KH will also drop slightly with CO2 injection as the carbon dioxide bonds with the ions that determine water hardness.


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## Junebug720 (Oct 6, 2003)

No CO2 yet. I filled the tank last night at about 9:00pm and the KH was 3 / PH 7.6. When I tested this morning at 7:40am the KH was down to 2 / PH 7.6.


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## Junebug720 (Oct 6, 2003)

Some additional information. In a separate container I have tested the water, the water + Amquel, the water + Amquel + the Texblast sand and in everyone of the cases the KH stayed 3. I am guessing that it has to be either something in the filter (ie activated carbon), one of the plants I have in the tank or the tank itself. I'm very new to this but I can't see one of plants being the culprit. Can activated carbon change the KH of water drastically?


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## DLeDeaux (Dec 27, 2002)

Activated carbon should be inert. Just to be sure you could try the activated carbon in a separate container. You're one step ahead on the troubleshooting process by testing your tap water!

It's rare to hear of KH dropping, usually it is the other way around where it is going up for no apparent reason.


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## malkore (Nov 3, 2003)

Kh will lower with CO2 injection, but its such a minor drop that the typical Kh test kit won't measure the difference (something like a quarter of a degree).

I too am facing issues in my wife's planted tank, with a Kh of 6 currently, while my tank, and the tap water, measure 8 degrees. She's only got pure florite for substrate, only sponges in the filter, and only 2 blue rams for fish. Luckily some water changes are helping bring the Kh back to 'normal'.

From what I was told, Kh will, over a long period of time, slowly drop, as will the pH...but we're talking months without a waterchange for that to happen...and her tanks not even 3 weeks old yet.
Truely baffling


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## Junebug720 (Oct 6, 2003)

Last night I put the carbon insert into the water that I had already tested at a KH of 3 and this morning it tested KH of 1. It looks like the carbon is causing the KH to drop. I knew that activated carbon could remove nutrients from the water but I had never read anything about it dropping carbonate hardness. I am going to do another water change on the tank tonight and see if I can get the KH back up.


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## magicmagni (Nov 7, 2003)

The tannins in your driftwood will lower the KH. The water changes will help, but you may just want to try and add some baking soda a little at a time each day untill you reach the target KH. Seachem also makes an Alkaline buffer that I like to use. Only raises KH.


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## Fat Guy (Nov 19, 2003)

magicmagni said:


> The tannins in your driftwood will lower the KH.


I didn't know that. I thought that the tannins only dropped the pH. I believe you, but is there an article that you know of that I can read about the affects of tannins on KH. I guess I could do a general search but....I'm lazy.


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## Junebug720 (Oct 6, 2003)

I think they have been running some soft water days in my area recently. I started adding baking soda to buffer the water back up and I was having to do this every morning but after the last water change the KH appears to have stabilized a bit. The testing continues.


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