NO3 + K2O dosing - The Planted Tank Forum
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post #1 of 15 (permalink) Old 01-03-2016, 03:18 PM Thread Starter
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NO3 + K2O dosing

I have a 100 gallon aquarium with two 35w cfl lamps and six 10w led floods. I am waiting for much stronger lighting (about 350 watts of LEDs) to arrive. I have a CO2 tank which is currently turned off while I wait on the arrival of the above-mentioned lighting, an inline reactor, and increased nutrients (the Java ferns were initially a lush green and pearling with the CO2 but then stopped pearling and started turning yellow - I'm guessing from the lack of nitrates). I am currently dosing Seachem Flourish (the standard version) twice a week and initial dosages (50 ml) of Flourish Excel with a syringe to treat a bba problem. However my java ferns have started turning yellow and nitrates are at 0.

I live in Israel, where imported "90% water" aquarium fertilizers are even more expensive than in the USA, so I was reluctant to spend money on a small bottle of Flourish Nitrogen. It is somewhat difficult to obtain Potassium Nitrate here as well. I went into a gardening store today and asked for Potassium Nitrate and they sold me a 2kg bag that says (I'm translating from the Hebrew):

Quote:
Potassium fertilizer rich in Nitrogen to compensate for a Potassium deficiency.

Ingredients:
- 13% Nitrogen (N) in the form of Nitrate - (NO3)
- 46% Potassium (K2O)
The product is quite coarse so my plan would be to dilute it in aquarium water before adding it to the tank, but my question is how much of it to dose?

Thanks
AJS

Last edited by spetnik; 01-03-2016 at 09:48 PM. Reason: Typo: I wrote NO2 instead of NO3
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post #2 of 15 (permalink) Old 01-03-2016, 03:41 PM
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That's 59%. What's the other 41%?
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post #3 of 15 (permalink) Old 01-03-2016, 07:05 PM Thread Starter
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I just noticed the product is made by Haifa Group Chemicals and repackaged by the retailer. I'll call the retailer tomorrow to find out exactly which product it is.

Last edited by spetnik; 01-03-2016 at 08:21 PM. Reason: Explained in the post
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post #4 of 15 (permalink) Old 01-03-2016, 09:43 PM
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It doesn't contain K2O, simply that the amount of potassium expressed as K2O is 46%. It's a standard.

Since the molecular weights of varying ions are different, they standardized the reading to K2O. If the potassium was in the form of K2O, it would equate to 46% of the product weight. But it's not, it's just elemental K attached to NO3. Lets look at N first.

Here, they've listed the product as containing 13% by weight as N, and then described that N as being in the form of NO3.

The molecular weight of NO3 = 62.0049
The molecular weight of N = 14.0067

62.0049 / 14.0067 = 4.42

So the conversion factor between N and NO3 is 4.42. Applying that to the description on the label gives 57.5% NO3. The easiest way to look at it is to say, the product contains 57.5% NO3, of which 13% is N.

The molecular weight of K2O = 94.196
The molecular weight of K = 39.0983

We need to see that K2O is a measure of a substance with two K for each O. So we must double the weight of K before finding the factor. 39.0983 * 2 = 78.1786

94.196 / 78.1786 = 1.2

So the conversion factor between K and K2O is 1.2. Applying that to the description on the label gives 38.33% K.

Adding these together nets 95.83%. The rest of the weight is made up by impurities.
It looks like they repackage this one.
One of the special grades would be better.

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post #5 of 15 (permalink) Old 01-03-2016, 09:47 PM Thread Starter
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Thanks for the reply. That was my guess as well (that it is the "classic" grade). Do you think that there is a risk in using this one? I'm not so sure how easy it will be to get one of the special grades. They get jumpy enough when I just ask for "potassium nitrate" (they don't take explosives or their ingredients lightly here - you can't even buy model rocketry kits).
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post #6 of 15 (permalink) Old 01-03-2016, 10:02 PM
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By and large, yes it should be safe. Some portion of the remaining weight will be impurities that aren't even water soluble.
If you're worried, shoot for under dosing rather then over dosing.

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post #7 of 15 (permalink) Old 01-04-2016, 01:55 PM Thread Starter
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I just added 1 tsp of the product to the aquarium (Fertilator said 3tsp to get it where I wanted so I figured to start with 1 for today). I saw that the product sunk to the bottom of the mixing cup, so I figured "why not just dump it in and let it become part of the substrate?" However, my fishies (particularly the tiger barbs and rosy barbs) decided it was food (!!!). I quickly fed them the usual tropical flakes but the barbs hung around the fertilizer until it disappeared (I don't know how much they ate and how much dissolved). I just hope I don't have a bunch of barbs floating at the top of the aquarium...
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post #8 of 15 (permalink) Old 01-04-2016, 08:40 PM
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My tiger barbs always think they're starving too, reminds me of my children.

Remove some tank water, mix the dose of powder in that tank water first, then add that tank water back into the tank.

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post #9 of 15 (permalink) Old 01-04-2016, 08:41 PM Thread Starter
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Quote:
Originally Posted by Audionut View Post
My tiger barbs always think they're starving too, reminds me of my children.

Remove some tank water, mix the dose of powder in that tank water first, then add that tank water back into the tank.
Would you happen to have any idea of the conversion in volume between granules and powdered KNO3?
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post #10 of 15 (permalink) Old 01-04-2016, 08:42 PM
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Go by weight, not volume.

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post #11 of 15 (permalink) Old 01-04-2016, 08:44 PM Thread Starter
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Quote:
Originally Posted by Audionut View Post
Go by weight, not volume.
Great. So now I need a scale. Would you venture a guess until I procure one? And yes - what is it with the tiger barbs and their appetites? Just the other day I was installing a powerhead and one of these wannabe piranhas nipped me, causing me to jolt my arm and cut myself on a piece of jagged glass on the top of the tank. I usually pretend to try to catch them before doing any in-tank work so that they will be scared of my hand.
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post #12 of 15 (permalink) Old 01-04-2016, 08:56 PM
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Are you going from granules to powder? Or vice-versa?

Take your standard dose of which ever, and measure that with a tea spoon (or other device) that holds the capacity you require. Now use some common sense.
Powder will be significantly heavier for the same volume as granules.

So if your standard dose is one heaped tea spoon of powder, the same heaped tea spoon of granules will be perfectly fine until you get some scales. On the other hand, if your standard dose is one heaped tea spoon of granules, you would probably only want around half that, maybe even a little less with powder.

A little to much for a short period of time is likely to have no dire effects, but then neither is not quite enough. The good thing about nitrogen, is that your fish supply some of this nutrient, and that it should be very easy to see a deficiency once it develops. So I would dose lean until you have the scales, or see a deficiency.

Wannabe piranhas, lol. That about sums them up.

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post #13 of 15 (permalink) Old 01-04-2016, 08:59 PM Thread Starter
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I just went into the kitchen cabinet and pulled out our mortar and pestle and am grinding to a powder. The stuff isn't really toxic per se' and it should all wash off anyway. Then I'm gonna mix it with distilled water in a washed-out Flourish Excel bottle and dose from there.

Also, I just finished reading The Martian. So every time I figure out some hack like this I feel like Mark Watney on Mars...

Last edited by spetnik; 01-04-2016 at 09:00 PM. Reason: ...
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post #14 of 15 (permalink) Old 01-04-2016, 09:17 PM
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Good idea, that should get you close.

Mark Watney, well he was playing with Hydrogen gas in a fragile environment, so he gets bonus points for danger. Ha!!

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post #15 of 15 (permalink) Old 01-04-2016, 09:38 PM Thread Starter
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Yeah, but this is potassium nitrate. I could make a bomb with it if I WANTED to. AND I live in Israel and my office is a bomb-shelter / sealed room (for chemical attacks). You can call it my hab. I don't have an air lock, but I do have a heavy-duty metal door that's supposed to protect us from bombs and missiles (and a year and a half ago when rockets were raining down from Gaza, the door to the shelter that my brother-in-law was in was blown open from the force of a nearby rocket explosion - kind of like airlock 1).

But okay, yeah Watney gets the win.
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Last edited by spetnik; 01-04-2016 at 09:39 PM. Reason: ...
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