EI dosing question on KNO3 - The Planted Tank Forum
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post #1 of 9 (permalink) Old 12-16-2013, 01:28 AM Thread Starter
Algae Grower
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EI dosing question on KNO3

EI dosing recommends adding KNO3 3-4 times a week, targeting an NO3 range between 5 and 30 ppm. My 20 gallon planted tank runs up to 40 ppm before water changes and 20 ppm after (as near as I can tell trying to match the API color chips). So should I forgo adding KNO3? Will the plants miss the potassium or will they get sufficient K from the KH2PO4 dosing? I'm using DIY CO2 and running in the range of 7 - 15 ppm per the pH-KH curves. 40 watts of light. Thanks for any insight you can share.
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post #2 of 9 (permalink) Old 12-16-2013, 02:17 AM
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I would forget kno3 and dose k2so4 instead, that will give you the K without the n. You may find as your plants grow faster that you need to start dosing n though.
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post #3 of 9 (permalink) Old 12-16-2013, 03:45 AM
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It isn't a good idea to rely on a nitrate test kit to tell you if you need to dose nitrates. Hobby grade test kits are not that reliable. The whole idea behind the estimative index dosing method is based on knowing that having more than enough of any of the nutrients the plants need does no harm unless you have several times the recommended concentrations in the water. That frees us to overdose on fertilizers, but prevent extreme build-ups of the excess fertilizers by doing big, regular water changes to remove most of the excess. Unless you really enjoy testing and calculating dosages, you will probably enjoy the hobby more if you just use the EI method, and forget about trying to test for each nutrient.

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post #4 of 9 (permalink) Old 12-17-2013, 01:56 PM Thread Starter
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Thanks for the advice! Yep, the attractive promise of EI is that makes testing unnecessary. I've just recently started my tank and am using CO2 for the first time, so I have been testing water parameters and observing the fish and plants as I go to understand what works. After I get a handle on how EI dosing works, I'll hope to do much less testing. One early observation is that as I have dropped the average tank pH from about 7.4 to 6.8, my tetras (neons and rosy tets particularly) have become much more "fiesty"! I guess that means they are happier?
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post #5 of 9 (permalink) Old 12-17-2013, 06:19 PM
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EI is more proactive and keeps folks ahead on taking care of water changes, etc and dosing is the by product of that.

Better to stay ahead than chase....the parameters.

As long as the tap water is decent, you have good growth, fish are happy, that's a best test kit.
Then you can do things like scape, garden etc.

Which is what your original goal was to begin with.

Tom Barr
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post #6 of 9 (permalink) Old 12-18-2013, 12:42 AM Thread Starter
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Mr. Barr, what a surprise to have you respond to my post. It was your excellent article on EI that got me interested in trying the technique. EI ferts and small fractional teaspoons are "in the mail". I'm looking forward to healthier plants and to eventually trying more demanding varieties. I'm also looking forward to my BarrReport user account eventually being activated ). Thanks!
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post #7 of 9 (permalink) Old 12-18-2013, 05:04 PM
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Well, ferts tend to be the easiest item, light can be also.
That leaves horticulture, aquarium care and then ....CO2 mostly.
CO2 gets everyone at some point.

EI just makes the ferts independent for plants, algae etc, so you can focus on other stuff. You can do more frequent water changes, more % etc on newer tanks, generally the 1-2 months after set up, say 2-3x aweek water changes, then taper off to once a week, or depending on the tank etc, 2-4 week intervals. I can go months, but I just like to keep a good habit and get in the tank and clean things up.

Non CO2 tanks generally get no water changes for months.

Some argue that EI requires "frequent" "laborious"(or any other disparaging adjective they can conjure up) water changes, which is frankly a bold faced lie. I use 50% weekly as an example, never a requirement. The user can modify to suit a number of trade offs and goals. If you have to lie to sell your dosing method, I think you need a better method. Dosing is moderately important, but many hobbyists place a much larger importance on it than say CO2 or light, which are by far, the much larger factors and drivers of plant growth.

A good article that explains this well (and ferts a little, they used non limiting ferts, similar to EI):


Tom Barr
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post #8 of 9 (permalink) Old 12-18-2013, 08:31 PM
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Tom, you mention that CO2 and lights often being more difficult than ferts (which makes sense). I understand the extremes and fickleness of lighting, but my question to you is where is CO2 difficult? I don't have anywhere near the experience most people here do but I have the understanding that so as long as those drop checkers are a nice lime green (and sufficiently away from your CO2 source for a more accurate reading) and your fish aren't gasping for life, CO2 will not be a limiting factor.

Where I guess I'm being shortsighted is in the delivery of CO2 to all parts of the tank (?). I have a tiny 5G (only hi-tech tank I have) so CO2 delivery hasn't been an issue for me.
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post #9 of 9 (permalink) Old 12-19-2013, 07:32 PM Thread Starter
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I found an interesting post here regarding my original question on dosing with KNO3 if the tank was running 40ppm nitrate. In a 10-19-2013 post regarding using EI ferts from GLA, Mark546 indicated that his tank ran 40ppm NO3 so he just dosed potassium and phosphate on his very first dose. Before his second dose he measured his nitrate as 5ppm! In the following discussions it was felt that his plants had been difficient in potassium and/or phosphate, and given those elements, the plants were then able to use the nitrate. I think I will try to repeat that in my tank when my ferts arrive.
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