# potassium kits



## geezer (Jun 7, 2006)

Are they worth buying? All this time I've not had a po4 kit until the other day. I thought I had a phosphate defiencey, and was dosing even more. Turns out it's off the richter scale now  

are potassium kits accurate? Big Al's didn't sell 

I am 50% happy with my plants, some grow like mad lush green, some look like they're dying. 

i currently own a nitrate and po4 test kit. my water is hard so i didn't bother with a calcium kit (if that's right) .


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## Salt (Apr 5, 2005)

You will get a lot of replies saying they are useless. I for one don't believe that and use one myself. When calibrating the kit with RO water it gave readings as expected.

There are two kit types you can find available for purchase. They both work by adding sodium hydroxide and tetraphenylborate to a tube with your water sample. If potassium is present, the sample will turn turbid (cloudy).

The first kit type only tests potassium levels between 1 - 2 ppm. It is available from a few different sources (for example, Aquariumlandscapes.net), but the design is the same. The kit comes with two permanently sealed test tubes, one with 1 ppm of potassium and one with 2 ppm of potassium. Both have the hydroxide & tetraphenylborate added already, so you can see what the test result will look like if the potassium level is somewhere below 2 ppm. Above that, and the cloudiness of the result will look the same.

The second kit type, the Lamotte Potassium kit, uses the same reagents, but uses a simple test tube system and distilled water to expand the readability to 50 ppm. You take your sample to one line, add distilled or RO/DI water to the second line, then your reagents. You then insert a second test tube into the first. The second tube has a black dot on the bottom. You hold it over an overhead light. When you can no longer see the black dot on the bottom, you take the reading from a gauge on the side.

I have not been able to find an online store where you can do an "add to cart" for the Lamotte kit, but if you send an e-mail to Clarkson Lab and tell them that you want to purchase the Lamotte 3138 Potassium kit, they will take care of you. It is expensive at $47.95.

Lamotte Potassium test instruction book


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## Tonka (Mar 20, 2004)

You can also buy this kit directly from LaMotte and get it within 10 days. No way yet to order online, but you can place your order with a very nice human at 1-800-344-3100.

Distributor Thomas Scientific has a website with online ordering, but they refuse to sell to private individuals.


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## trenac (Jul 16, 2004)

If you are dosing the proper ferts you should not have to worry about a potassium deficiency. I personally would not buy one, I wasted my money on one myself.


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## HeyPK (Jan 23, 2004)

I have a LaMotte Potassium kit, and have had it for about 5 years, and it is still going strong. They say that it is good for about 100 tests, but I think it is good for at least 300 tests. It just takes 2 drops of the sodium hydroxide solution and a tiny little spoon of the tetraphenyl borate powder. I never bother measuring the amount of potassium. If I get a precipitate, there is sufficient potassium. If the solution stays absolutely clear, then it is time to add more. With nutrients like potassium, calcium and magnesium I tend to add a good bunch and expect them to stay there until the plants use them up. So, I only test rarely for potassium. Plants are good at taking up potassium from low concentrations. If the plants bring the potassium down to the level where there is no precipitate, my guppies can start to develop skin lesions and fungus growths. If potassium is not added, they will start to die.

The LaMotte web site makes it very difficult to find what you are looking for, but I stumbled on the link for all its individual test kits, including the one for potassium:Potable and Wastewater Testing Kits: Potable & Wastewater Testing Products - © LaMotte Company


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## Tonka (Mar 20, 2004)

I agree that testing for potassium is not necessary. Furthermore, I believe that if you faithfully adhere to EI you don't need to test for anything.

But this is a hobby, not a job. Inquiring minds just want to know.....


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## Zapins (Jul 28, 2004)

It would be useful to know potassium levels, especially if you are adding a lot of K2SO4 KNO3 and other potassium containing nutrients to avoid getting levels high enough to inhibit plant growth. 

I had 500 + ppm of potassium and for the longest time I had no idea what was causing the calcium-like deficiency in my plants, until I had the water professionally tested.

Pity they cost 50$ though...


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## Newt (Apr 1, 2004)

I'm buying a kit. I think it is very useful to know what your potassium level is. Not testing for it is like saying "I'm not going to test for nitrates because I have fish in my tank and therefore I have nitrate".

I have a 75 gal tank with 100% flourite and have been dosing Flourish Potassium as directed since starting it over six years ago. All of a sudden I had holes appearing in my swords, my apono was looking terrible, the leafs began falling off of my bacopa and algae began to grow on the swords and began looking yellowish. I suspected K deficiency so I doubled my potassium dosing and things began to improve a bit. I am now dosing K every day and the plants have come back and looking MUCH better BUT I still don't know if I have enough or too much.

Not everyone does EI dosing. To test is to know!

Thanks for the info on the test kits. Seachem is developing one but they dont know when it will be released.


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## Glouglou (Feb 21, 2006)

If you got the money for it, go ahead. More I test and less I need to test because, by recording everything and be aware of the chemistry of my water I can start to comprehend causes and effect. If I have a little bit of cash coming my way, I will probably buy a potassium kit. For now I am trying to calculate all the potassium input ( but being chemically challenged) it take me time to figure out...

But the problem without a test kit, you have no way to know the consumption rate...

People seem to pinpoint around 30 ppm without problems (potassium seem to have a larger range acceptable???)


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## Newt (Apr 1, 2004)

I ordered one today direct from LaMotte this afternoon.

I too record everything I do but this one sneaked up on me and I have no idea why. Perhaps the potassium in the flourite has been used up. I'm in the habit of testing and don't mind doing it. Busy hands, happy heart.


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## hoppycalif (Apr 7, 2005)

As far as I know Flourite doesn't supply potassium to the plants. It may supply some iron, but not potassium. And, if you use any test kit expecting results you can rely on you have to first calibrate the test kit, and recalibrate it periodically. I have seen many people post here and on other forums that they don't dose nitrate, for example, because their test kit always shows that they have plenty without dosing, but their plants won't grow - that is a test kit problem. And, the same is a common statement here about phosphate.

If your job requires knowing something a test procedure tells you, you are always required to calibrate the test procedure, usually before every test. At least that was my experience in two different types of jobs. It doesn't matter that the calibration almost always shows the test procedure to be accurate - you only know this by calibrating.

For what we are doing, growing aquatic plants as a hobby, knowing how much of anything is in the water to any degree of accuracy isn't a requirement. It may be interesting and worthwhile for that reason, but it isn't necessary in order to be successful at raising aquatic plants. If you are doing a study, collecting data to be presented to a scientific publication, that is a different story entirely. Then, you will probably spend the money required to get very good test kits, but still calibrate them.


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## Newt (Apr 1, 2004)

Seachem lists potassium at 2195 ppm in flourite. I assume it would supply it to the plants but I'm not certain.

I periodically calibrate my test kits or compare to a known solution.

Thanks for the tips, Hoppycalif.


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## hoppycalif (Apr 7, 2005)

Newt said:


> Seachem lists potassium at 2195 ppm in flourite. I assume it would supply it to the plants but I'm not certain.
> 
> I periodically calibrate my test kits or compare to a known solution.
> 
> Thanks for the tips, Hoppycalif.


Flourite is a baked clay product, so it is essentially inert. The iron is available primarily because so little iron is needed, compared to the NPK needs, that it can supply some, and it adsorbs cations, making them more available to roots. The list of "ingredients" in a baked clay product is just what the clay is made of, not what is available to the plants.


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## Glouglou (Feb 21, 2006)

Hoppy is right. Some have misconception that anithing is available from Flourite, Turface, Soilmaster etc but in fact a very small amount of plant available nutrients will leach from these baked clay. They are more appreciate for their CEC capacity (Cation Exchange Capacity). This is the capacity to absorb nutrients from the water to release it to the roots.

Laterite is little bit different it will leach more iron because it's a naturally deshydrated clay not as "vitrified" as the others.

You can see some CEC of popular substrat here:
http://home.infinet.net/teban/jamie.htm


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## Newt (Apr 1, 2004)

If that's the case then I'm even more stumped as to why I began showing potassium deficiency after more than four years. Nothing changed in my maintenance routine.

Now that I am dosing three to four times the amount of K my plants have recovered and are looking healthly again.

Any clues?


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## hoppycalif (Apr 7, 2005)

Tom Barr continually tells us that just because we do something and something happens, it doesn't mean that what we did caused the something to happen. Science isn't that easy. You would have to have two identical tanks, control everything about those tanks rigorously, to be sure they remained identical. Then introduce a single change to one tank, and observe what happens, to have a pretty good idea that what you introduced actually caused the changes you saw. Then to verify that you were correct, you would repeat the test, and introduce the change to the other tank. After doing this several times and always seeing the same result you could say for sure that what you did caused the change.

So, it is possible that your increased dosage of K wasn't what fixed the problem you had. It is also possible that it was what fixed it.


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## Newt (Apr 1, 2004)

I got my potassium test kit the other day and ran a test last night. I guess I've caught up on my dosing as I had ~40ppm. But the plants are looking great again and algae has all but disappeared.

I did experience some white 'foam' at the top of the tube even though I shook the tube continually. It made it a bit difficult to read the square tube.
Now am I supposed to read the measurement based on the depth of the sq. tube in the round tube or by how much water has entered into the sq. tube??? I would think that the level would equalize but it appeared as if the water level in the sq. tube was lower but then again my view was obsured by the 'foam'.


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