A sudden spike of nitrites in both my tanks

[joelfernandes]

Hello all.

I had fully cycled tanks (29 gallons + 5 gallons), and a bit more than a month ago, I had a camallanus outbreak in both and ended up having to treat both tanks for one month. The fish are now fully treated, but recently I noticed my fully-black mollies started to show some fungus (post about it here). I tested the water back then, and to my surprise, a scary spike of nitrites, back then at around 4ppm! I did daily or every other day WC and within a week, I got 0 nitrites again.

Unfortunately, a couple of days ago I got high nitrites reading again and I'm now back to daily water changes. There are no signs of ammonia and PH reads normal too (around 8.2). What could be happening here?

Oh, and yes, I do use conditioner (Prime).

 

[AdoraBelle Dearheart]

Did you use any medications to treat the fungus recently?

What kind of filter do you have, and how do you clean it?

Has anything else changed in the tank? Any dead fish/snail that could be throwing things off?

Does the tank have any live plants?

Any new fish or other additions/changes?

 

[jaylach]

By any chance did you use any anti antibiotics? If so keep in mind that such can also kill the good bacteria needed for tank health.

 

[joelfernandes]

The only medication I used was Fritz Expel-P. Once a week for a whole month, with constant water changes.

The filter I use is a sponge filter with some ceramic balls at the bottom (this one). It's been a while since I last cleaned the sponges, definitely longer than a month now. But the way I clean it is by squeezing it using the water from a water change.

As for dead fish, I did have a casualty when treating for camallanus, and I took the fish out as soon as I saw it (it was overnight, so in less than 10 hours, give or take).

What changed in the tank is that I took out all the decor when I treated for camallanus, as I had an algae problem back then, too, so I decided to re-do the scape. Still today, I only have the filter, a large fake plastic bush plant and gravel. I thought back then that could have been a problem with bacteria, but I monitored for the first two weeks, and it was always fine (it wasn't really that much decor anyway).

The one thing that makes me wonder is, as I said, I had an algae issue before the camallanus, and I took out some plants + duckweed. Recently I dipped those in bleach diluted with water (1 part bleach, 20 parts water). I dipped for a minute or so and then rinsed really well with water + conditioner. I left the plants in a bucket with water + conditioner for 24 hours and then put them in the tank. It could be that, but, it's odd that it didn't do anything to ammonia, and, not to mention, I had the same spike two weeks ago as well, way before putting the plants back in.

 

[TwoTankAmin]

Plants are great filters. They out compete bacteria for ammonia and the plants do not make nitrite or nitrate. The bacteria love all over a tank, wherever they can have what they need delivered. This incudles in the substrate, one the decore, any hard surface as long as it is shade. the bacteria are somewhat photophobic.

If you remove decor and plants together you have an ammonia spike you may have miissed and that caused the nitrite spike. The ammonia bacteria reproduce faster than the nitrite ones.

Also, I have been bleach dipping plants for over 20 years. After I rinse them in tap, I dip them in a bucket with dechlor. Then I return them to the tank. There is no reason to wait 24 hours if you follow that method. I normally dip most -plants for 90 seconds in a 19-1 (water to bleach) mix. Annubias go for 2 minutes and very delicate plants I do a test dip first and if it doesb't trash the plant, I dip them. Some plants cannot handle chorline.