Crazy High Ammonia-Help!

[enb9422]

Hello all. I have an established 20 gallon tank with 5 tetras and 6 cory cats and a 50 gallon filter. It's almost two years old. I noticed last night that the fish were acting very mildly lethargic (they're usually very active) and the cory cats hadn't eaten their food from the past few days. The cories alternate between veggie tabs and shrimp tabs; tetras get tropical fish "crisps." Both sets have always been very good eaters.

Anyway, I got the old food out, gave them a little time to calm down, and then fed them. I went back about 15 or so minutes later and all the food was sitting on top of the gravel (cory food and tetra food). Concerned, I did water tests and almost had a stroke when I saw my ammonia was at 6-8ppm. Ph is at 6 (which is has been for a few months; more on that later). Other water measurements were fine. I moved two months ago and went from well water to "city" water. Prior to moving, I never had issues with ammonia or ph. I use stress coat and tap water conditioner when I do water changes.

I immediately did a 50ish% water change and vacuumed the gravel. That helped bring it down some, but not nearly low enough. When I plugged my filter back in, it would not come on. I immediately ordered a new filter to pick up today as this all occurred at 10:00 pm last night and I work all day today. I plan to do daily water changes until problem gets under control and test my tap water (I stupidly never tested it).

My questions are: can anyone give their opinion as to how/why this happened and how to stop it from happening again? Could my filter have been slowly dying and affecting the water? I clean their tank/gravel/water regularly, and all 11 fish are accounted for. In two years, I haven't experienced anything like this, so am I extremely concerned to put it lightly. Please help!

 

[Colin_T]

Hi and welcome to the forum

Too much food too often.
Any uneaten food will rot and produce ammonia for as long as the food is in the water. If the filter wasn't working properly, then the ammonia levels would have gone up and stressed the fish. When you added more food the fish ignore it because they are stressed and the ammonia levels keep increasing.

Regular filter maintenance is essential to keep the filter clean.
Big (75%) regular water changes and gravel cleaning the tank help keep the water and substrate clean.

Until the new filter arrives, stop feeding the fish and do a 75% water change and gravel clean the substrate each day. Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

While you are waiting for the new filter, wash the old filter materials in a bucket of tank water. When it's clean wash it in another bucket of tank water and then put the materials in the aquarium. Keep the filter materials in the tank until the new filter arrives and then put them in the new filter.

Try to aerate the tank with an airpump and airstone. If you don't have one then get a small plastic container and scoop some tank water out and pour it back in. Do this for a couple of minutes every hour during the day.

If you have live plants in the tank, have the lights on for 16 hours a day. It will encourage algae and plant growth and they will help use any nutrients in the water. Once the new filter is set up you can reduce the lighting back to 12 hours a day or whatever you had before.

When the new filter arrives, only feed the fish a couple of times a week for the first month and monitor the ammonia and nitrite levels. Do a 75% water change and gravel clean the substrate any day you have an ammonia or nitrite level above 0.

 

[Essjay]

The pH is what has kept your fish alive. At this pH just about all of that high ammonia reading is in the non-toxic ammonium form. At pH 6.0 and a temperature of 25 deg C/77 deg F, 6 ppm total ammonia contains just 0.0035 ppm of the toxic ammonia form. Our test kits read both ammonia and ammonium as 'ammonia'.


But you still need to get the reading down to zero.

 

[Byron]

Agree with essjay. But before any of us can offer advice, we must know the parameters of your source water. The GH (general or total hardness), pH and KH (carbonate hardness or Alkalinity, though this is the least important of the three for our purposes here). This is for the tap water alone. Check with the water authority, on their website, or call them, unless you have tests for GH and pH. Remember you need to out-gas the CO2 in tap water before testing pH (this is not needed for tank water or for other tests like GH).

You have to be careful. If the pH of your tap water is above 7, doing massive water changes here will likely kill the fish, because the relatively harmless ammonium will immediately change back into ammonia. This is why tanks that have not been maintained with adequate water changes or overfeeding for whatever reason can benefit from smaller water changes to restore things. But without knowing the GH and pH of the tap water, we cannot be certain.