04-25-2017, 08:31 PM
Join Date: Apr 2005
Location: Brentwood, CA, USA
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| | Re: Question about low nitrates in water column
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.