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Description
Seachem Flourish NitrogenNitrogen is one of the main three macro nutrients (nitrogen, phosphorus, potassium: NPK) required by plants and can often become the limiting factor to growth in a flourishing system. Flourish Nitrogen is a concentrated (15,000 mg L) blend of nitrogen sources. It provides nitrogen in both the nitrate form and the plantpreferred ammonium form. However, no free ammonia is released because the ammonium in Flourish Nitrogen is complexed and unavailable
Nitrogen is one of the main three macro nutrients (nitrogen, phosphorus, potassium: NPK) required by plants and can often become the limiting factor to growth in a flourishing system. Flourish Nitrogen™ 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. Ammonium becomes available after conversion of urea (carbamide). Flourish Nitrogen™ also provides nitrate for those plants that can readily utilize nitrate as well. For maximum benefit, use with Flourish Phosphorus™ and Flourish Potassium™. Flourish Nitrogen™ is safe for invertebrates such as shrimp.Sizes: 100 mL, 250 mL, 500 mL, 2 L, 4 L
Directions
Beginner
Use 2.5 mL (half a cap) for each 160 L (40 US gallons) twice a week or as needed in response to signs of nitrogen deficiency (e.g. stunted growth, chlorosis). For smaller doses, please note that each cap thread is approximately 1 mL.
Expert
The beginner dose raises nitrogen by the same degree that 1 mg/L nitrate would. This dose is sufficient to provide approximately 4 g of growth (dry) or about 20 g (hydrated) over a 1 month period (assuming all other necessary nutrients are provided). For increased growth use proportionately more.
To target a specific nitrogen increase, dose according to the following formula: 0.25vn=m, where v= volume of tank in gallons, n=desired nitrogen increase (if using a “nitrate equivalent” value for “n” then use a factor of 0.05 instead of 0.25 in the formula) and m=volume of product to use in mL. For example to raise 20 gallons by 0.20 mg/L nitrogen you would use: 0.25*20*0.20=1 mL.
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.
FAQ
It says on your label that Flourish Nitrogen™ provides nitrogen in both the nitrate form and the ammonium form. Isn't ammonia bad?
A: Ammonium and ammonia are not the same thing. No free ammonia is released because the ammonium in Flourish Nitrogen™ is complexed and unavailable until utilized by the plants.
Why does Flourish Nitrogen™ have two forms of nitrogen in it?
A: In studies we have done isolating the effects of the ammonium form and nitrate form of nitrogen on plant growth, we have found that most plants prefer to utilize nitrogen in the ammonia (ammonium NH4+) form. Note, however, that certain plants derive a greater benefit from the nitrate form (NO3). That's why Flourish Nitrogen™ contains both the nitrate form as well as in an ammoniacal equivalent form.
I thought nitrates were bad and could lead to unwanted algae growth. Why would I want to add it my aquarium?
A: This is true, but only when nitrogen levels become excessive, that is, when there is more nitrogen available than the plants can use. When this happens, it becomes available to algae. Nitrogen is still vital to plant growth, though. Flourish Nitrogen™ should be used in cases where there is a nitrogen deficiency.
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Exchange/Return Notes
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★★★★★ 3
Runs small
Size: X-Large, Color: Navy
Runs small and is short. Nice dark navy color. I ordered a size up and it is still small.
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Reviewed in the United States on February 26, 2026
★★★★★ 5
Great tee
Size: X-Large, Color: Medium Grey Heather
It’s a nice cotton material…not thin, just perfect. After washing, it also kept its shape.
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Reviewed in the United States on February 18, 2026
★★★★★ 5
Wonderful t-shirts
Size: X-Large, Color: Medium Grey Heather
These t-shirts are well made and have a nice thick feel to them. The sizing is spot on.
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Reviewed in the United States on April 17, 2026
★★★★★ 5
Unpaid and honest review
Size: Small, Color: Navy
Nice fit ,lightweight ,good quality and very very affordable ,comfy.Recommended
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Reviewed in the United States on June 10, 2026
★★★★★ 4
Runs small
Size: XX-Large, Color: Navy
Definitely go a size up. These run a whole size smaller than designated. Material is also heavier than a regular t-shirt. Quality seems okay
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Reviewed in the United States on May 17, 2026