Nitrite And Nitrate

[angel-al]

ok ive got two questions for u but i need simple answers if possible.
1. If ammonia is virtually non toxic in a low ph environment as is is converted to ammonium- what about when its converted into nitrite. Would the ph have no relevance and if so would products such as ammo lock suddenly be rendered useless
2. Does a deep bed of gravel help keep nitrate levels lower due to low oxygen levels and if so is it better to skim the gravel rather than "digging deep" when doing a gravel clean?

ok more than 2 questions but answers would be appreciated

 

[Truck]

with a low PH nitrite is very toxic, but is less toxic in an alkali solution

 

[angel-al]

with a low PH nitrite is very toxic, but is less toxic in an alkali solution

should I ask why

 

[Truck]

its just how it is

 

[angel-al]

do u know about the nitrate and deep gravel

 

[Truck]

deep gravel beds can contain anaerobic bacteria which can convert nitrates to nitrogen if un disturbed

 

[Bignose]

with a low PH nitrite is very toxic, but is less toxic in an alkali solution

should I ask why

if you haven't read through it, may I suggest reading thorough my old post [URL="http/www.fishforums.net/index.php?showtopic=154313&"]http/www.fishforums.net/index.php?showtopic=154313&[/URL] wherein the ammonia-ammonium equilibrium with pH is discussed in detail.

In very short, pH is the measure of the H+ concentration in the water. low pH = higher concentration of H+ ions.

And, the ammonia-ammonium balance is:

NH3 (ammonia) + H+ <--> NH4+ (ammonium)

And, quite simply, when there are more H+'s around, because the pH is lower, more of the H+'s will bond themselves to the NH3's and form NH4+'s. And, it just so happens that ammonium (NH4+) is less toxic than ammonia.

What happens in the nitrite balance is similar.

Nitrite is an ion, NO2-

It too is in balance with H+ ions, specifically between nitrite and nitrous acid.

NO2- (nitrite) + H+ <--> HNO2 (nitrous acid)

So, again, when pH is low, there are more H+'s around to bond with the nitrite ions and form nitrous acid. The nitrous acid form is the more toxic of the two. But, the difference here is that nitrous acid is a fairly weak acid (it doesn't give up its H+ as easily as some of the stringer acids like hydrochloric HCl or sulphuric H2SO4), so even across the board there will be a significant around of nitrous acid no matter what. It is weak enough that over the entire range of middle pH's (4 to 10) at least 90% of the nitrous acid/nitrite will be in the form of nitrous acid.

So, when the pH is low, there is more nitrous acid than at higher pH's, but there is always a significant amount of nitrous acid around. Meaning that the toxicity isn't nearly as dependent on pH as the ammonia toxicity is.