Tropical Fish Keeping - Aquarium fish care and resources

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makoy1995 03-24-2013 05:12 PM

nNitrogen query?
why is NH3 and urea not used as source for N in aquarium?

JDM 03-25-2013 12:19 PM

Ammonia is the primary source.


Byron 03-25-2013 12:56 PM

Jeff is correct. Aquatic plants obviously require nitrogen, but unlike terrestrial plants, aquatic plants prefer ammonium. This is usually plentiful in an aquarium with fish, and plants will readily take it up (as ammonia or ammonium, they can change ammonia to ammonium). Only when ammonia/ammonium is exhausted will they turn to other forms of nitrogen, and studies suggest the next is nitrite. Nitrate is their third choice. This is because it takes more work for the plant to change the nitrite and nitrate back into ammonium, which they must do.

There are a few aquarium plants that seem to prefer nitrate, or at any rate take it up more easily. But these are few.


MoneyMitch 03-26-2013 03:57 PM

Guaranteed Analysis
Total Nitrogen (N)
Soluble Potash (K2O)
Derived from: potassium nitrate, urea (iminium salt)

is a concentrated (15,000 mg/L) blend of nitrogen sources. It provides nitrogen in both the nitrate form and the plant-preferred ammonium form. However, no free ammonia is released because the ammonium in Flourish Nitrogen™ is complexed and unavailable until utilized by the plants. Flourish Nitrogen™ also provides nitrate for those plants that can readily utilize nitrate as well

straight from seachems website on their nitrogen product.

makoy1995 03-26-2013 05:59 PM

oh i see, so ammonia could be a good source of N for the plants? but ammonia could burn our fish, right?

Byron 03-26-2013 08:20 PM


Originally Posted by makoy1995 (Post 1551154)
oh i see, so ammonia could be a good source of N for the plants? but ammonia could burn our fish, right?

I don't know your level of knowledge obviously, so bear with me. Nitrogen occurs in 3 forms in the aquarium, as ammonia/ammonium, nitrite and nitrate. A fourth, nitrogen gas, dissipates into the atmosphere and rarely remains in the tank. Aquatic plants use the ammonium as their nitrogen.

Ammonia/ammonium comes from fish respiration and the breakdown of organics in the substrate. It is highly toxic, and can harm fish at very low levels, and will kill them if too high. We obviously do not want to be adding ammonia to a fish tank, there is more than enough naturally. But the plants grab this fast, faster than bacteria in fact. There will usually be sufficient ammonium in a fish tank.


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