Cycling anomalies

[Jasongtr]

We've just started with a little fluval evo 13.5g

The tank has a marco rock (never been used before) aquascape, and I used caribsea ocean direct sand.

I did start to ghost feed flakes and pellets but soon realised I'm not patient enough for that despite already having a 75g tank running.

I'm monitoring ammonia and ph with my seneye and it's been going up very slowly and got to 0.086ppm *so still very low.

I added a few small rocks that have been in our 19 month old tank for about 6 weeks about 5 days ago, one of these is very small, around 2" cube size bit has been in for all 19 months.

Today I added Dr Tims one and only and an hour later added 25 drops of ammonia, so about 2x drops per gallon.

According to the seneye the ammonia after 90 mins has only gone up to 0.108ppm so I tested nitrite, I figured if I got a reading then the live sand and additional rocks from the other tank must of started processing the ghost feeding and dosed ammonia as I figured the ghost feeding from 5/6 days ago wouldn't be showing nitrite yet would it?

Nitrite test in pics, no point testing for nitrate yet I guess as I'd be reading that from the ghost feeding I guess.

Does any of the above sound right?

 

[KrisReef]

Anomaly? Seems like if you put 2 liters of petrol in an automobile and then an hour later your tank meter only shows 1 liter then i would presume that the car engine must have been running for at least some time in the past hour.

If you then go to the tailpipe with the car running and measure carbon monoxide I would wonder why you wouldn't expect carbon dioxide (the end product of full combustion) to also be present with the car running.*

The car is running, the live rock and sand are doing something, not unexpected, I don't get the anomaly question?

I don't know what a normal functioning fish tank would measure an hour after a dose of ammonia, but I wouldn't expect it to be zero with fish present?

*Many people have tanks running that they have to dose NO3 to keep it detectable. I don't think most newly established tanks would be processing nitrate into nitrogen gas but if it did the NO3 would appear to be zero in a cycled tank. Adding ammonia, the nitrogen processing bacteria should remove ammonia, producing some nitrite and then nitrate but again nitrate might not show, but I would expect it to in this instance>

 

[Jasongtr]

It's not cycled though, certainly not yet, just added another 25 drops, it's gone to 0.142 ppm.

I'll leave it until tomorrow and check nitrites

 

[Randy Holmes-Farley]

It's not worth measuring nitrite, except to see if it is interfering with nitrate testing. Nitrite is no concern in a reef tank.

The only issue of concern when cycling in this fashion is to make sure ammonia can be depleted rapidly.

 

[Jasongtr]

It's not worth measuring nitrite, except to see if it is interfering with nitrate testing. Nitrite is no concern in a reef tank.

The only issue of concern when cycling in this fashion is to make sure ammonia can be depleted rapidly.

I wouldn't normally but when I added 25 drops and the ammonia went from 0.07 to 0.108 I thought it wise to check if it was being converted quickly due to the live sand and additional rocks from our other tank, another 25 drops has made it go to only 0.142, I expected it to be much higher like 2.0ppm

 

[Dan_P]

I wouldn't normally but when I added 25 drops and the ammonia went from 0.07 to 0.108 I thought it wise to check if it was being converted quickly due to the live sand and additional rocks from our other tank, another 25 drops has made it go to only 0.142, I expected it to be much higher like 2.0ppm

The Seneye measures unionized ammonia. Very roughly, total ammonium is about 10x higher than what the Seneye reads,

Secondly, unless the Seneye has been calibrated, the measurement is off above 0.01-ish. When the Seneye reading returns to below 0.005 ppm free ammonia, the concentration of total ammonia is close to zero.

 

[Jasongtr]

The Seneye measures unionized ammonia. Very roughly, total ammonium is about 10x higher than what the Seneye reads,

Secondly, unless the Seneye has been calibrated, the measurement is off above 0.01-ish. When the Seneye reading returns to below 0.005 ppm free ammonia, the concentration of total ammonia is close to zero.

Our seneye was reading 0.016 in our other tank it never went lower than that and that is what I've seen others do too

 

[Jasongtr]

The Seneye measures unionized ammonia. Very roughly, total ammonium is about 10x higher than what the Seneye reads,

Secondly, unless the Seneye has been calibrated, the measurement is off above 0.01-ish. When the Seneye reading returns to below 0.005 ppm free ammonia, the concentration of total ammonia is close to zero.

Where did you get this 10x total ammonium as the seneye reads nh3 free ammonia and nh4 total ammonium my nh4 levels are 17ppb

 

[Randy Holmes-Farley]

Where did you get this 10x total ammonium as the seneye reads nh3 free ammonia and nh4 total ammonium my nh4 levels are 17ppb

The ratio of ammonium to ammonia is fixed by pH.

Ammonia and Ammonium as a Function of pH
The pKa of ammonium in seawater is about 9.3 (some references state 9.5, with the difference possibly relating to the different pH scales sometimes used for seawater and freshwater).2 That pKa means that at pH 9.3 the water has equal concentrations of ammonium and ammonia. At pH values below this level, as is always the case in reef aquaria, ammonium predominates. Figure 1 shows a plot of the relative fractions of ammonia and ammonium as a function of pH in seawater. At pH 8.2 only about 7% of the ammonia is present as free ammonia, with 93% present as ammonium.

Because many authors attribute ammonia's toxicity primarily to free ammonia (whether this is correct or not, see below), Figure 2 shows an expanded view of Figure 1 for the free ammonia concentration over the pH range of usual interest in reef aquaria. The amount of free ammonia present at pH 7.8 is about one-fourth the amount present at pH 8.5.

Reef aquarists also are often interested in pH values below those typically present in actual reef aquaria. A shipping bag containing fish, for example, often drops substantially in pH over the course of hours to days, as a result of expelled carbon dioxide. That change in pH can convert even more of the free ammonia to ammonium, and Figure 3 shows the fractions of ammonia and ammonium on a log scale, making it clear that the free ammonia continues to drop in concentration as the pH drops, even when it is already present as a very small fraction.

 

[Jasongtr]

The ratio of ammonium to ammonia is fixed by pH.

Ammonia and Ammonium as a Function of pH
The pKa of ammonium in seawater is about 9.3 (some references state 9.5, with the difference possibly relating to the different pH scales sometimes used for seawater and freshwater).2 That pKa means that at pH 9.3 the water has equal concentrations of ammonium and ammonia. At pH values below this level, as is always the case in reef aquaria, ammonium predominates. Figure 1 shows a plot of the relative fractions of ammonia and ammonium as a function of pH in seawater. At pH 8.2 only about 7% of the ammonia is present as free ammonia, with 93% present as ammonium.

Because many authors attribute ammonia's toxicity primarily to free ammonia (whether this is correct or not, see below), Figure 2 shows an expanded view of Figure 1 for the free ammonia concentration over the pH range of usual interest in reef aquaria. The amount of free ammonia present at pH 7.8 is about one-fourth the amount present at pH 8.5.

Reef aquarists also are often interested in pH values below those typically present in actual reef aquaria. A shipping bag containing fish, for example, often drops substantially in pH over the course of hours to days, as a result of expelled carbon dioxide. That change in pH can convert even more of the free ammonia to ammonium, and Figure 3 shows the fractions of ammonia and ammonium on a log scale, making it clear that the free ammonia continues to drop in concentration as the pH drops, even when it is already present as a very small fraction.

Fair enough, read it once, now glazed, I'll try again later

 

[Randy Holmes-Farley]

Fair enough, read it once, now glazed, I'll try again later

My first sentence is all you really need to know:

The ratio of ammonium to ammonia is fixed by pH.