Originally Posted by Seattle_Aquarist
Plants absorb their nitrogen first from nitrates, secondly from ammonicial nitrogen sources, and finally from urea. I know that urea is inexpensive but why use a source of nitrogen that plants cannot uptake efficiently?
you are completely wrong my friend, plant uses NH4 before any other source, in my dosing i could have included NH4 but after testing it out, i only included algae in my tank and plus its risky business. Urea is similar to NH4 but instead it breaks down into NH4 inside the plant and they use it right away. if plant don't use it it turns into nitrate in matter of minutes, good bacteria does this. nitrate can be taken up by plants but at much slower rate, i have included nitrate in my solution just in case if plant do absorb all the urea, you will still have nitrate source to back it up for the plants.