# Question about low nitrates in water column



## # 1 Plant Boy (Feb 9, 2016)

Hi, 

I have a medium to high light tank. It is moderately planted. I tested the nitrates and it reads 0ppm. I am using aquarium plants.com total substrate fertilizer that has potassium nitrate in it. Should I also be dosing nitrate in the water colum. I have alteranthia renekii that isn't producing much any new leaf growth. I also have bacopa australis that some of the stems are dying since I cut them way down to 3 nodes above the substrate. Could not dosing nitrates in the water colum be the cause?

Thanks


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## DutchMuch (Apr 12, 2017)

Could be, are you still cycling your tank though?


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## hoppycalif (Apr 7, 2005)

Before you do anything else, make sure you are using the nitrate test kit correctly. If you don't shake up the reagent bottles well enough you will get false very low nitrate readings. You have to shake the second bottle hard and for a long time. You can also do a simple test of the test kit. Add a pinch or less of KNO3 to a cup of water, then test it to see if the kit shows you have lots of nitrate. I have read lots of posts where people have had false low nitrate readings.


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## # 1 Plant Boy (Feb 9, 2016)

Not still cycling the tank. I also have been using my liquid nitrate test kit correctly. I also have alot of amazon frogbite that I think could be using up the nitrates.


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## swmnwdsfishes (Mar 30, 2017)

You've answered your own question. Your plants are utilizing all the nitrate in the tank. Your main culprit is the frogbit. Since it floats, it has access to the air which has about 400ppm CO2. The submersed plants only have access to about 3ppm in a non-CO2 injected tank (30ppm are recommended injected levels). When plants break the surface they get a boost of growth due to the more availible CO2. Heavily planted tanks and tanks with floating or emersed plants are usually low in nitrates. You could dose nitrates, but not just potassium nitrate. You need a balanced fertilization regimen with phosphates and trace elements as well. 

Sent from my SM-G935T using Tapatalk


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## # 1 Plant Boy (Feb 9, 2016)

Ok thanks. So even though I am using a substrate fertilizer that has all the micro and macros in them should I still be dosing the water column with nitrates and phosphates ect? Also the levels of co2 in my tank are at 23ppm. My Kh is at 3 ppm, Gh is at 5ppm, ph is 6.6. What would be a way that I could get 30ppm of co2?

Thanks


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## hoppycalif (Apr 7, 2005)

You can't possibly know your ppm of CO2 accurately enough to say it is 23 ppm. Unless you are using a $2000 CO2 probe you can, at best guess the ppm within about +/-5 ppm, so if you are using a valid method to determine how much CO2 you have, you can only say you probably have something around 25 ppm. What method are you using? Are you adding CO2 to the water? Is it pressurized CO2 or DIY CO2? The way to get more CO2 in the water is to add more CO2 to the water. If you are adding none, you have around 3 ppm of CO2, not 23 ppm. That 3 ppm comes from atmospheric CO2 dissolving in the water. If the tank has been set up for a fairly long time, and the substrate contains organic matter, you might get a few ppm more CO2 from breakdown of the organics in the substrate.


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