Ammonia again?

[Clockwork-crow]

I have a 15 gallon tank with two medium sized sponge filters 5 sparkling gourami and 11 dwarf corydoras. It's been running for about 6 months but yesterday I did a check and my ammonia is at 0.5-1ppm. I feed a small pinch of flake+3 corydoras pellets once every two days, and have a heavily planted tank. The only thing I've changed recently is cleaning one of the sponge filters, I emptied some water from the tank into a bucket, took the sponge out and rinsed it in the tank water, put more water from the tank in the bucket, repeat. I tested my nitrates today and they were zero, but I also have lots of duckweed so suspect that might be causing that? I've added seachem prime but in the meantime, any advice?

[Wren.shi]

The same thing is happening with me! I've also got a well planted tank that consumes 10ppm nitrates (from fertilizer) every day but I have been testing consistent 0.25ppm ammonia for several days, feeding 6 pellets and one algae wafer per day.

Have you tested your tap water for ammonia? (I'm assuming you replaced the water used to clean the sponge filter with tap water).

Also, from what I've heard and in case you didn't know, Prime can detoxify 1ppm ammonia and 2ppm nitrate per dose for 24 hours, so dose accordingly.

Good luck with your tank!

[Patrick_G]

To be honest I’d be looking to see if one of the fish has died as that might be the cause of the Ammonia. 

[HH Morant]

If I have an ammonia problem, I stop feeding until it is resolved. I don't know why your tank does not seem to be processing the ammonia. There is often about .5 ppm ammonia in my tap water, but I use Prime to bind the ammonia for 24 hours. Within 24 hours, the plants and bacteria in my tank turn the ammonia into nitrites and then the nitrites into nitrates so that I have zero ammonia and zero nitrites. The only thing I can think of is that there may be something in your tank that is decomposing - something that is not obvious.

[HH Morant]

I like your tank, by the way. It's a chaotic jungle like mine.

[Isaac M]

Looking at your stocking and your aquarium visually, I am having a hard time imagining your aquarium is having a tough time processing ammonia unless there is something decomposing in there giving off lots of ammonia as mentioned. The only other explanation I can think of is that you are getting a false ammonia reading. I have taken a screenshot from seachems website in the FAQs section of Prime and how Prime can give off false ammonia readings. I hope that helps! 

[Bill]

Once a tank is cycled, I've never really seen a problem with ammonia spikes, unless the water quality is really bad... I've sometimes seen unexpected nitrite spikes in tanks that I thought were cycled, but really didn't build up enough BB that consumes nitrites. What are your nitrate and nitrite readings with that level of ammonia?

 

[Clockwork-crow]

Okay I have a tentative hypothesis. Whilst the duckweed (yes I know, I was naive) is thriving I have noticed I have way less elodea than I usually have. Since my nitrates were 0 I would perhaps guess the duckweed has been outcompeting the elodea for nutrients and causing it to die off in an ammonia bomb, and I've forgotten to add fertiliser lately