Odd Goings On... A Little Confused.

[Sideshow86]

Hi everyone.

Well my aquarium was going really well until about 3 days ago.

I always had consistant readings of 0ppm Ammonia and 0ppm Nitrite. And a Nitrate level of about 20ppm. The pH is 8.1 and temperateure of 78'F.

Everything was going so well that one morning we came down to 8 molly fry!

Suddenly the Ammonia spikes to 0.5ppm and it just will not budge. But the Nitrite and Nitrate levels havn't changed one bit either. Ive dropped the temperature down to 76'C, reduced the feeding to bare minimum and I have been carrying out 50% water changes. This drops it to about 0.25ppm straight after the water change but its usually back up to 0.50ppm 24 hours later.

Now the wierd thing is that all 6 Mollys and 8 Fry are 100% fine. (They are the only fish we have in a 125L tank.) They have no gill problems, not gasping at the surface and not acting lethargic.

Very confused to A, what the problem is and B, why a high level doesnt seem to be affecting them.

I also checked my tap water and it reads 0.00ppm!

Any help please. D

Cheers.

 

[Gvilleguy]

No tank cleaning or filter cleaning prior to the problem? Did you swap out some filter media? I'm no expert on fish fry - it just doesn't seem like 8 little fry would contribute much ammonia to the tank.

 

[Sideshow86]

Usual stuff really. Waterchange (20% every 3-4 days) Cleaned the filter about a week ago by wafting it around in the tank water i'd just taken out until the major bits were off. And the filter media is still the same.

Only thing I can think of is that my plants are not looking as healthy as they were, but they are are still alive. I think they only look a little shabby as the molly like to nibble on them.

 

[mattlee]

to get the ammonia level down to 0 a bigger water change is needed. if you get a reading of 0.5 and do a 50% water change then you are removing half of the ammonia giving the test result of 0.25 as you have been getting. i would do a very big water change of about 80% making sure the new water is pretty much the same temperature as the old water removed, due to the amount of water replaced

 

[waterdrop]

Agree with mattlee that regardless of the -cause-, you need to modify your actions in this sort of situation to meet the challange of the higher ammonia levels detected. The answer is always as mattlee indicates, much, much larger, longer gravel-clean-water-changes. Doing a really high percentage change often has the effect of making the followup ones easier.

I suspect what you are seeing is a mini-cycle associated with the new fry. Fry are deceptive in that they respire more quickly (a large amount of the ammonia production we see from fish is the result of ammonia coming off the gills - they do not retain ammonia waste like we do (we retain it in order to filter and preserve the water inside our bodies)) and they are growing more quickly, so they represent a larger bioload than their smaller size would lead you to believe.

This is no big deal probably and you just need a period of daily stat monitoring with associated water changes just like you would do in fishless cycling (you have to anticipate that 0.25 is the max ceiling you want and figure out what pattern of changes allows you go go about your responsibilities and still be home to change water before it goes above 0.25 again.) Mini-cycles are usually short as the biofilter is mature and will only take a few days to respond and grow bigger and handle the new bioload.

There is always the small chance that something else is wrong that you just haven't detected yet, so its good to keep notes on things in your aquarium notebook during periods like this.

~~waterdrop~~