What is potassium nitrate? - The Planted Tank Forum
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post #1 of 7 (permalink) Old 11-01-2009, 05:27 PM Thread Starter
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What is potassium nitrate?

What is potassium nitrate and how do I monitor levels? Is potassium nitrate the same stuff that seachem sells as nigtrogen? Can levels be monitored with a nitrate test kit?
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post #2 of 7 (permalink) Old 11-01-2009, 05:43 PM
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My flourish nitrogen bottle says it provides nitrogen in both the nitrate form and the plant preferred ammonium form. The solution is derived from potassium nitrate, urea (iminium salt).
It also says that because one half of the nitrogen in flourish nitrogen is from nitrate you can get a reasonable estimate of nitrogen levels by doubling a nitrate reading, or, you can use seachem's multitest: Total Nitrogen (coming soon) to accurately measure total nitrogen while distinguishing between nitrate, ammonia and organic nitrogen.

Personally I just add all the nutrients in the proper doses twice a week regardless what my test kit is showing me. I do a 50% WC weekly. My nitrates stay between 20-50 ppm. My test kit is not calibrated, I more so use test kits to give me a general idea of what my tank is doing. I use the tank appearance itself to judge if there is a problem.

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post #3 of 7 (permalink) Old 11-01-2009, 05:51 PM Thread Starter
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Thx for the help!

I'm growing aquarium plants emersed and I'm trying to figure out how to fertalize them correctly. My set up don't have a filter or anything to provide nitrates. And I'm getting blue green algae growing on the substate. I was told to increase and maintaine potasium nitrate at 20ppm. I'm not sure how to do it.
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post #4 of 7 (permalink) Old 11-01-2009, 05:58 PM
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Do you have any pics of your set up?
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post #5 of 7 (permalink) Old 11-01-2009, 08:38 PM Thread Starter
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Here is a video. I'm not using the sprinkler system anymore.

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post #6 of 7 (permalink) Old 11-01-2009, 08:56 PM
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You can buy dry potassium nitrate, KNO3, from:

If you read the sticky on dosing methods, and follow the EI dosing amounts you will do pretty well even for emersed plants, which I am assuming have their roots in the water. If not, just do the same, and dose each plant separately a few ml of a mix of water and KNO3.

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post #7 of 7 (permalink) Old 11-02-2009, 03:22 PM
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To measure NO3 from KNO3:

Lamotte is about the best trade off for decent results, ease of use, runs 50$.
Refills fairly reasonable however.

Still, with all NO3 and PO4 test kits, you MUST calibrate them to see if the ppm's are accurate. This is the same reason why they calibrate pH monitors/meters routine.

You have no way of knowing(in otherwords, you are guessing) whether the reading is correct unless you compare it to a standard known reference.

Here's a semi easy way to do it:


You can also use a scale to 2-3 decimal places and do this also.
VERY few aquarist bother to do this, but plenty of hobbyists tell others to test these parameters, generally forgetting, or simply not knowing how to calibrate or even that they need to, they just assume the readings are correct.

Getting aquarist to do this step is like pulling teeth as you can image, particularly with folks not familiar with KNO3 etc and all the other stuff.

Water changes are much easier to explain and get folks to do, so that and experience knowing when to do a water change is a much easier sell to planted aquarists. Then you dose known amounts(nothing runs out), and change the water(nothing builds up).

Much easier for 99% of folks.

Tom Barr

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