Another disaster

[XnSdVd]

Apparently nitrate uptake only occurs after ammonium is reduced to less than 0.5mg/l in the case of Elodea nuttallii. Chances are it's similar in other plants.

What levels are toxic for our fauna?

[Quixotic]

Diana did mention that fish health is more critical than whether plants grow better with ammonium. She also states the fact that plants take up ammonium preferentially does not guarantee all of them will grow better, though she hypothesises that they probably do.

The whole idea is that considering plants readily take up ammonium and probably grow better, biological filtration (nitrification) can be deemphasised in aquariums with healthy aquatic plants.

...Ammonia is a great way to induce several species of algae...

Interesting, any specifics on what are the species of algae? What is the mechanism behind it, as it induces only several algae and not all?

What levels are toxic for our fauna?

Not sure if there is an absolute level, but according to a study from University of Florida, unionised ammonia (UIA) of 0.05 mg/l may harm fish. As UIA approaches 2.0 mg/l fish will begin to die. I guess very much depends on the sensitivity of the fish as well.

[XnSdVd]

True, but it's also been proven that in the absence of essential elements like potassium, photosynthesis and therefore nitrate uptake, practically grinds to a halt. Also, what's the difference between ionised and unionised ammonia?

[Quixotic]

Ammonia occurs in two forms in water, NH4+ and NH3. They are called Total Ammonia Nitrogen (TAN). Test kits normally tests for TAN.

NH4+ is ionised Ammonia because it has a positive electrical charge.
NH3 is called unionised Ammonia since it has no charge.

NH3 is the form toxic to fish and it is a small fraction of TAN.

Water temperature and pH will effect which form is predominant. If water temperature and/or pH is high, NH3 will be high.

Given the specific water temperature and pH, NH3 can be calculated from the TAN.

[XnSdVd]

Interesting... so a low temp and acidic water will keep NH3 down?

[Quixotic]

Chemistry anyone?

Free Ammonia-Nitrogen Calculator & Information
http://cobweb.ecn.purdue.edu/~piwc/w...monia/nh3.html

How-To Information Regarding the Derivation of Free Ammonia-Nitrogen
http://cobweb.ecn.purdue.edu/~piwc/w...erivation.html

[PeterGwee]

NH3 is more toxic when the pH is higher while temperature doesn't/shouldn't have much effect on NH3.

Bacteria converts the NH3 into less toxic NO3 via nitrification (use alot of O2 in the process and destroys some alkalinity thus lowering the pH) while plants use it as a nutrient via photosynthesis (release O2 as a by product).

Where is this thread heading? I think the thread starter just need to add anti-chloramine during the water changes and he should be fine.

Regards
Peter Gwee