Adding ammonia to a cycled tank when fish are not present

[An t-iasg]

I had to put my betta Peyton in a QT tank a few weeks ago. (Well, he did get a bit battered around in the Superbowl, lol!)

His fins were beginning to turn white at the tips. His body color was fine, and his activity/behavior was good too. I put him in the QT without meds for a few days. In his home tank, there are a lot of plants and it was a little hard to monitor him in there.

After a few days in QT, I decided to medicate. I used Jungle Fungus Eliminator, and he was well within two courses of treatments. His color did actually return to the fins.

Anyway, the point of this post: Peyton was in QT for about 12 days. I put one drop of 10% ammonium chloride in his home tank (5 gallons) every other day. Before returning him to the tank, I did an ammonia test and it was 0. I proceeded with my 50% water change, and added him back to the tank. I swear he danced around when I asked him if he was ready to go home! He went right to his favorite plant. The tank's biofilter and the plants held up very well during his absence with the added ammonia.

[Zagz]

That is exactly what I do if for any reason I have to remove fish froma cycled tank. Works very well IMO.

[An t-iasg]

This was my first time to try this method. I didn't try to keep the bacteria alive with food since the tank just had a simple sponge filter, with no real mechanical filtration (extra floating bits of food would not be removed). I was happy that the ammonia was 0. Do you have a method for calculating how much ammonia per bioload or tank size? I was wondering, before I did the ammonia test, that if the ammonia was not 0, then the biofilter could have run into trouble from not enough ammonia to keep it alive, or I could have added too much ammonia. Luckily neither scenario seemed to be the case.

[Zagz]

Nope I am like you, I added it with no calculations, and luckily it worked. I think once the cycle is complete it doesn't take much ammonia to keep things going. I've also been lucky enough to never have to do this with a tank over 20 gals. So smaller amounts of ammonia work well.

[An t-iasg]

It does seem like the small amount was just fine. I wanted to "err" on the side of too little rather than too much but it worked out well.

[Zagz]

It seems that we are of a few that believe in this method. LOL. It worked well for me too.

[maxwell1295]

I use that same method whenever one of my QT/holding tanks or fry tanks is empty, which hasn't been very much lately...

[squawkbert]

It's a good way to go, but you ought to go ahead and do the math so that you're adding at least 1 or 2ppm NH3.

For example, let's call 5 gallons 20L. 2ppm would be 40mg which would be about 40µL of pure ammonia, but you have 10% ammonia, so it's 40µL/0.1=400µL which is 0.4mL.
Using the standard 20 drops per mL, 8 drops should be roughly 2ppm for a 5 gallon tank.