# drop checkers



## foster (Sep 2, 2012)

What drop checkers are everyone using? I have been looking at the Red Sea indicator. Seems pretty decent for the cost. Any recommendations would be appreciated.*c/p*


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## Chididdy123 (Jul 21, 2012)

Amazon.com: Freshwater Plant CO2 Indicator with Solution Aquarium: Pet Supplies

Amazon.com: U.P. Aqua Co2 Indicator: Pet Supplies


Both cheap and do the job just fine. I have the first link, and it has been doing me good, its cheap 4 dkh solution surprisingly works well haha


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## Gizmo (Dec 6, 2010)

I use the Red Sea indicator, and use tank water solely because I know my tank is at 4dKH. It's never given me any problems.


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## foster (Sep 2, 2012)

Will I get a skewed co2 reading if the tank water is not a 4dKH?


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## Gizmo (Dec 6, 2010)

Yes. KH is carbonate hardness and the presence of carbonate ions makes pH change less easily. The color solution you add into the water in the drop checker is a pH reagent. Therefore, higher KH means that reagent won't change color very easily. Too little KH and the reagent will change too easily. The standard ~30ppm of CO2 is most accurately represented in a drop checker using an exact 4 degrees of KH.

Most hard core planted tank enthusiasts create a 4dKH solution using distilled water and baking soda (sodium bicarbonate), because things like phosphates which are normally present in fish tank water can affect the drop checker readings as well. I have very soft water with a 3 to 4dKH so I don't worry too much about it.


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## foster (Sep 2, 2012)

How would I go about making 4dKH solution.? I need to test my aquarium water to see what the kh actually is. Thanks for the info!!


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## foster (Sep 2, 2012)

I tested the water for KH= 9dKH. PH is between 7.6, and 7.8. I was under the impression that CO2 would lower the PH by buffering the KH. Is that an incorrect assumption? The test results are pretty much consistent across all 4 tanks of mine. One is co2 injected using pressurized system, the others are DIY(yeast) co2.


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## coralbandit (Jul 29, 2012)

Mix distilled water with sdium bicarbonate(very little) until you get 4dkh.Gizmo nailed it ,but here's what the masters say;
Best way to get KH4 solution


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## foster (Sep 2, 2012)

Thanks for the info, and the link also. Its been MANY years since I had chemistry.*old dude Might take a while to retrieve that lost knowledge*laugh out loud. Guess I will be playing mad scientist tomorrow.!!


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## tbub1221 (Nov 1, 2012)

Sounds fun , let us know how it works out 4 you.


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## foster (Sep 2, 2012)

I will let you know how it goes. Sounds like add a little and test, take a little out and test. Good thing I have a lot of patience NOT!!


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## foster (Sep 2, 2012)

So any guesses on how much bicarb to add to 2 liters of water to get around 4dKH? Planning on mixing in a 2 liter soda bottle.


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## coralbandit (Jul 29, 2012)

It sounded like very little.I would try less than 1/8 teaspoon in 1 litre and test, then you can add water if it is strong(higher than 4) .If it is higher than 8 than I would dump some so adding another litre would cut it by 50%.Just guessing and doing math.


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## foster (Sep 2, 2012)

Good news on the 4dKH solution. Spartan brand purified drinking water is exactly 4dKH. I only had to try one time mixing, and realized the water was near perfect. I tested the water straight without adding SB, and its perfect. Sure saves a lot of experimenting.*w3 Pretty sweet, one gallon of drop checker solution for $1.05


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## Gizmo (Dec 6, 2010)

pH, KH, and CO2 have a very close relationship. KH doesn't change easily, and the higher the KH the harder it is for elevated CO2 levels to drop the pH. pH and CO2 don't affect the KH levels in your tank, think of KH as the pivot point on a seesaw and CO2 and pH on opposing ends - CO2 goes up, pH goes down, and vice versa.

Glad to hear you got your 4dKH solution


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## foster (Sep 2, 2012)

So I got my drop checker today, put in 1ml. of 4dKH water and a few drops of PH test reagent, and it stays yellow-orange color. the same color of the test reagent. People have said to use the blue reagent, but mine is orange. Now what? If I use the test solution that came with the drop checker, and use aquarium water then its blue. Just a little confused here.*c/p*


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## Gizmo (Dec 6, 2010)

pH reagent (methylene blue, I think is the name) should be a greenish-blue straight out of the bottle. Are you sure you're not using the high-range pH reagent?

Try using the reagent that came with the drop checker, and the 4dKH water instead of tank water. That should be your best indicator.


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## foster (Sep 2, 2012)

SUCCESS FINALLY 
I picked up some distilled water tonight, mixed sodium bicarb into it until I had exactly 4dKH. Took a little sample, and put PH reagent test solution in, and it turned blue with the first drop. I have never been so happy to see dark blue in my life*w3. One more lesson in planted tank keeping learned. Thanks to everyone who guided me in this adventure!!


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