topping off during a cycle

[JMorris271]

Hi guys
Would someone that know share with me how does topping off for evaporation affect the ammonia level when cycling? It seems to me that the readings would be skewed.
Merci.

 

[Happyschneider]

Ammonia should not evaporate. So if you did not top off with rodi water, the ammonia concentration would increase (assuming that there was no oxidation taking place). However, at the same time you would have your nitrogen cycle oxidising your ammonia to nitrite and you would probably not detect those variations with a standard test kit anyway.

Topping off is really to keep the salinity constant. For the cycle probably not the most important thing as long as the salinity does not get way too high but once you have higher organisms in your tank, you really want to keep it as constant as possible.

 

[JMorris271]

I understand salt doesn't evaporate. I did not know that the same held true for ammonia as it is in liquid form . I was just wondering about dilution but realize that 4,000,000,000 wouldn't be doing it if it wasn't the correct thing to do. Thanks for clearing that up for me.

 

[Happyschneider]

Oh, I see. you are worried that ammonia evaporates and you would be left with too little ammonia for the cycle to complete?

Ammonia as a very low boiling point. I think it is around -30°C
Ammonium on the other hand is much higher: around 30°C

However, these numbers are for very highly concentrated solutions. Without having looked into the details, I would not expect a lot of evaporation. In any case, it would not affect your nitrogen cycle.

I did my cycle the same way, although my system is covered.

 

[JMorris271]

So then there is no need to keep adding it to the water to keep biological growth moving along until the fish kick in. OK.
What about water changes?

Thanks

 

[toothybugs]

Once you see it disappear in 24 hours and nitrite hits zip you're done. That is most likely going to happen within 1 water change cycle (unless you change your water every day). Topoff really should have no effect. Run your tank at 76-77 instead of 80 if it makes you feel better about the evap, it won't dramatically affect your cycling period but maybe a day or two longer.

Ammonia/ ammonium has such an incredibly high affinity for water I wouldn't worry about it evaporating from solution. Run a couple bumps up to 2ppm, watch em disappear, then call it a done deal yo.

 

[disc1]

I understand salt doesn't evaporate. I did not know that the same held true for ammonia as it is in liquid form .

It's not in its liquid form in your aquarium. It is ionized and dissolved in water. It's in a salt form if you will.

 

[Happyschneider]

So then there is no need to keep adding it to the water to keep biological growth moving along until the fish kick in. OK.
What about water changes?

Thanks

Here is what I do: I add ammonia to a total concentration of 2 ppm. I wait till all ammonia and nitrite is gone. During that time I do no water changes and I do top off with RO/DI (to keep salinity stable, probably not necessary in a closed system as mine as I do not have much evaporation, might be different for others).

Once all ammonia and nitrite is gone, I again bring it to 2 ppm. If this disappears within 24 hrs (both ammonia and nitrite disappeared within 24 hrs) I trust the system to be able to cope with the first addition of fish.

I have absolutely no evidence for this protocol except my extremely limited experience. It basically comes from what I have read here and elsewhere. I had about 50% life rock in my first system and it took me less than a week but this obviously will be very different for other systems.