Low pH and high ammonia, what happened?

[kddawg333]

Good Evening,

I am new to this forum and thank everyone for their time and expertise.

I have a 35 Gal hexagon freshwater aquarium. This tank is about 10 months old. It is heavily planted (see below)

There are currently: 1 angelfish, 10 neon tetras, and 8 Emerald cories.

Things were going well until about 6 weeks ago when we had a power outage for about 24-30 hours during which the filter was not working. Afterwards, there was a slight ammonia spike to ~ 0.5 - 1 ppm that I thought was secondary to die off from the filter. This was managed with water changes.

Then, for some reason about 2 days ago there was a huge spike in ammonia to ~ 2-4. This was also accompanied by a drop in the pH. Normally the pH sat around 6.8, but now it is around 6.0. I performed a ~ 50% water change without really accompanying change in ammonia or pH. I then caved and bought an ammonia remover as a filter insert, and this unfortunately didn't change the water parameters either. And now two cories have died [coated in a white like substance?!}

The rest of the parameters are - nitrite 0 ppm, nitrate 25 ppm [kind of confusing? clearly some ammonia is being cycled]
chloride 0 ppm, carbonate KH 0 ppm.

Anyone have any suggestions as to what is going on? What do I do from here? I have removed as many fish from the aquarium as possible and have them in another place, but I want to fix the main aquarium.

 

[BettaFishGirl]

Did you buy any new fish for the aquarium recently? Gravel vac and do another 50% water change. Check and make sure your filter is working and/or it's not clogged up...seems obvious, but it might be the culprit. Keep doing 30-50% water changes until ammonia is stable...test everyday too.

 

[kddawg333]

Thanks for your response.

No, no new fish recently, last ones were added in December 2022.
I have been vaccuming the gravel on water changes.
I just checked filter and it seems to be working well, no clogging or debris.
Will continue with water changes, daily, thank you!

 

[BettaFishGirl]

That is so strange though. A sudden drop in pH can affect the ammonia, such as overfeeding, not doing maintenance, but your tank looked very healthy, so there really wouldn't be a reason

 

[Colin_T]

Check the tap water for ammonia, nitrite, nitrate and pH. Your water company might have changed water source or screwed up dosing chlorine/ chloramine.

If your tap water is good and has 0 ammonia, 0 nitrite and 0 nitrate, and a normal pH, do a 75-80% water change and gravel clean the substrate every day until the ammonia level is 0ppm.

Don't waste your time doing small water changes. They don't dilute anything.
If you do a 25% water change, you leave behind 75% of the bad stuff in the water.
If you do a 50% water change, you leave behind 50% of the bad stuff in the water.
If you do a 75% water change, you leave behind 25% of the bad stuff in the water.

 

[kddawg333]

Tap water looks good.
Ammonia - 0 ppm
Nitrite - 0 ppm
Nitrate - 0 ppm
pH is around 7.2

I just performed a ~ 70% water change, and will continue to do this daily.
I'm just worried that I will need to do water changes daily indefinitely until the issue is identified?

 

[Byron]

Given the running time and the plants, this is not anything I would ever expect. If nitrate is zero in the source water, and 25 ppm in the tank, something is going on that should not go on. Nitrate in my many tanks never went over 5 ppm, and may have been much less, the API test first level was 0 to 5 ppm. I would however add some substantial floating plants, like Water Sprite, Frogbit or Water Lettuce. These are particularly fast growers and that means they can easily assimilate ammonia/ammonium rapidly, faster than the nitrifying bacteria.

The dead cories may well be part of whatever. I don't guess with disease issues, so I'll move on.

The drop in pH is normal in any aquarium over time but subject to the GH and KH. The latter is zero, so the pH is free to drop, which is not an issue given the fish (mine went down to 4's or 5's for years). What is the GH and
KH of the tap/source water on its own?

What is the substrate? If this is, or contains any form of so-called plant enriched substrate, this could well be the issue.

One note on substrate--when the grain size is as large as shows in the photo, cories are not suited. Gravel and whatever harbours bacteria that will affect substrate fish, whereas upper fish are usually OK. Soft sand is needed so the cories can do the digging they expect to do to find food, and it is amazing how clean they keep the sand. Food bits get trapped in gravel, and for cories this can be deadly.