4dkh Solution Warning on eBay - The Planted Tank Forum
 
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post #1 of 9 (permalink) Old 11-10-2010, 04:00 AM Thread Starter
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4dkh Solution Warning on eBay

Just thought I'd give you all a heads up if you're planning on buying 4dkh solution from "user name removed" on eBay. I used his/her solution in my drop checker for the past few days with 3 drops of API's PH test solution. The mixture only turned a slight blue-ish green color in my aquarium and I noticed that some of my fish were going up for air (I'm using a DIY setup with about 50 bpm diffused using a siphon head and bio balls) I bought API's KH test kit today to test the 4dkh solution. It took 5 drops to change from blue to yellow, making the solution 5dKH. I contacted the seller about this error, I'll update with what s/he replies with.

With all the testing equipment out I went ahead and made 2 cups of my own 4dKH solution, took about 20 minutes.

Last edited by sewingalot; 11-12-2010 at 06:05 AM. Reason: Do not post usernames or give reviews on them.
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post #2 of 9 (permalink) Old 11-10-2010, 05:31 PM
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Your test with the API KH test kit can be viewed as a calibration of that test kit, or as verification of the 4 dKH solution. I suspect it should be viewed as calibrating the KH test kit.

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post #3 of 9 (permalink) Old 11-10-2010, 06:04 PM
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I agree with hoppy. Your fish will show signs of co2 much before the drop checker changes, as well.

I suspect that your test kit is off, not the standard. Test kits need to be calibrated... and what you did likely calibrated it.

Also, if you just started using co2, your fish might take some time to adjust. go slow and they will get use to it easier. Also, making sure there is adequate surface agitation to keep more oxygen in the water will help. You might lose a little co2, but you gain much more oxygen and it is worth it.
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post #4 of 9 (permalink) Old 11-10-2010, 06:27 PM
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Why trust the alleged 4dkh solution sold here/ebay over the API test though? Anybody can post a picture of a bottle that has "dkh 4.00000000374" written on it and tell you it was tested extensively at a lab by a friend.

I will buy a bottle from ebay and ask my wife to test it. They got all sorts of measuring tools at the pharma lab she works at.

65g planted tank - 200W heat - PC 192W/6700K - Eheim 2217 - Pressurized CO2 - EI Dosing
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post #5 of 9 (permalink) Old 11-10-2010, 08:32 PM
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Are the three drops of ph solution reliable?

65g planted tank - 200W heat - PC 192W/6700K - Eheim 2217 - Pressurized CO2 - EI Dosing
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post #6 of 9 (permalink) Old 11-10-2010, 08:42 PM
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pH solution is bromothymol blue. You could use two, three, four or five drops in our purpose and it would be fine. A good solid blue is all we worry about. With testing Kh or even pH, you are more concerned with both consistency of drop size and interpretation of color. Much like interpreting a drop checker.
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post #7 of 9 (permalink) Old 11-10-2010, 11:56 PM
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I don't know if pH test kits are accurate or not. I haven't tried to figure out a DIY method for calibrating a pH test kit. One thing I read suggested that they can be inaccurate - the test reagent is made with a very basic chemical being added, for reasons I don't recall, if I ever knew. That suggests that the purpose might be to adjust the reagent to give the right colors for different pH's, which would be a possible source for errors. I think I will start thinking about how to calibrate the test kit.

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post #8 of 9 (permalink) Old 11-11-2010, 01:07 AM Thread Starter
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This is all very surprising to me now. If the API test kit isn't valid then what is a valid test of KH? GitMoe thanks for getting back to me, message coming your way.
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post #9 of 9 (permalink) Old 11-11-2010, 02:31 AM
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Quote:
Originally Posted by ObjectAgnosia View Post
This is all very surprising to me now. If the API test kit isn't valid then what is a valid test of KH? GitMoe thanks for getting back to me, message coming your way.
No matter what you buy to use to measure or test something, it has to be calibrated before use if you want to depend on the readings you get. Even micrometers are calibrated before use by serious mechanics. Even a precision pressure test gage, guaranteed to be accurate to +/- .01% has to be calibrated before actually relying on it for a good measurement.

But, our hobbyist test kits are not precision test devices by any definition. They are cheap. Cheap trumps reliability, accuracy, longevity, when you are referring to hobbyist stuff. Any test kit may be right on the money across the full range it is good for, as unlikely as that is, but if you don't calibrate it you can't know that.

Fortunately I don't know of any planted tank water parameter that we need to know with good accuracy. So, using uncalibrated test kits does no harm unless you decide that they are perfectly accurate and then do something serious as a result.

Hoppy
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