Need Advice: Sudden Ammonia Spike

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Cabinetman 1

Cabinetman 1

Candiru
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Jun 12, 2016
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I just checked water parameters on both my 120 gallon tank with 6 Red Hook Silver dollars and 220 gallon with two peacock bass. The ammonia on the 120g is at 1ppm, nitrites are at 0mgl and the nitrates are at 25mgl. The pH has also dropped from 6-6.5 to 4-4.5. The tank has been established since July and had weekly water changes. I checked the parameters this evening because today the silver dollars showed a major decrease in appetite. I also decided to test the 220g and the ammonia is at a 4ppm, nitrite 0mgl and nitrate 25mgl. The pH has also dropped from 6-6.5 to 5.5. That tank has been established for over a year and has always had weekly water changes. Both tanks are filtered by canisters. The 220g has 3 FX6's and one ehiem 2080. The 120 is filtered by one FX6. I added prime to both tanks tonight and I am making up some RO/DI water and will do a water change on both as soon as possible. Any ideas as to what is going on? Thank you
 
pH crash due to kH depletion. kH is consumed as part of the nitrification process. If you have soft water you have to monitor pH and/or kH.

Forgot to mention that nitrification stops at low pH so you'll start seeing ammonia.
 
Thanks for the reply. I am adding a kh buffer to bring up the pH and build kh. Should the bacteria recover once pH and kh are raised? Thanks for the help.
 
Trying to make sense out of this with missing metrics takes speculation.

Here's a few things to ponder:

1) Test your water out of the tap to make sure that's not the source of the ammonia

2) Explain your feeding and water change sequence and timing: when in that process did you test the water. Is that when you normally test it?

To get 4 ppm ammonia requires a high % of the weekly allotment of food in a short time considering that the nitrates never get over 25 ppm. In short, you would have had to feed around 50-70% of the weekly food all at once and tested the water about 4-10 hours later. If it was a lot less than 50%, you couldn't have 25 ppm nitrates, because 4 ppm ammonia already equals 15 ppm nitrates.

3) water depleted of phosphates will inhibit BB growth (Nitrosomonas requires it a lot more than nitrobacter) which might explain why nitrites are zero while ammonia is very high. That could be related to the switch to R/O water in July. (Does R/O remove phosphates?)

The low pH is the only reason the fish aren't suffering heavily from the ammonia, so stop feeding, and clear that up before you try to fix the pH. And the pH as has been said is being caused by the ammonia, not the reverse (even though it's indirect.) It could be low kH, so that needs to be tested.

Unfortunately, a lot of this might indicate the R/O water is an issue (low kH, low phosphates, etc.) but I don't use R/O water, so that's total guess work.
 
Last edited:
Drstrangelove said:
Trying to make sense out of this with missing metrics takes speculation.

Here's a few things to ponder:

1) Test your water out of the tap to make sure that's not the source of the ammonia

2) Explain your feeding and water change sequence and timing: when in that process did you test the water. Is that when you normally test it?

To get 4 ppm ammonia requires a high % of the weekly allotment of food in a short time considering that the nitrates never get over 25 ppm. In short, you would have had to feed around 50-70% of the weekly food all at once and tested the water about 4-10 hours later. If it was a lot less than 50%, you couldn't have 25 ppm nitrates, because 4 ppm ammonia already equals 15 ppm nitrates.

3) water depleted of phosphates will inhibit BB growth (Nitrosomonas requires it a lot more than nitrobacter) which might explain why nitrites are zero while ammonia is very high. That could be related to the switch to R/O water in July. (Does R/O remove phosphates?)

The low pH is the only reason the fish aren't suffering heavily from the ammonia, so stop feeding, and clear that up before you try to fix the pH. And the pH as has been said is being caused by the ammonia, not the reverse (even though it's indirect.) It could be low kH, so that needs to be tested.

Unfortunately, a lot of this might indicate the R/O water is an issue (low kH, low phosphates, etc.) but I don't use R/O water, so that's total guess work.
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I tested the Kh it was at 0. The R/O water has 0 ammonia and 0 Kh. I am thinking it was the pH crashing. I did test the ammonia after feeding. Maybe too soon after feeding? I typically test in the morning before feeding. I did add a buffer to bring the Kh up. It is up to 4 now, and pH is up as well.
 
Cabinetman 1 Cabinetman 1 You need to be careful making adjustments that impact PH with ammonia present in the system. At low PH ammonia is ionized and in the form of ammonium (NH4)which is not as toxic to fish. As PH rises the chemical bond with nitrogen will change and the ammonia will be in its unbound form (NH3) which is the toxic form.

http://www2.ca.uky.edu/wkrec/pH-ammonia.htm
 
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RO will remove phosphates.

If I recall correctly at a low PH ammonia is less toxic than at higher PH, but then the bio bacteria isn't active either. Scary!

Hope you can fix it! :)
 
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Hendre said:
RO will remove phosphates.

If I recall correctly at a low PH ammonia is less toxic than at higher PH, but then the bio bacteria isn't active either. Scary!

Hope you can fix it! :)
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Would adding a product like Stability help lower the ammonia?
 
If you're removing phosphates and have low phosphates (below 100 ppm) and not replenishing them, the BB will be inhibited. Ammonia will be the first indicator as I posted before. If you're removing kH, then your pH will decline pretty rapidly when nitrification is present. Low pH (5.5 and below) and high ammonia (above 4 ppm) will also inhibit the BB. Thus, that would make 3 separate factors that inhibit nitrification, each of which is capable of putting BB into cellular hibernation.

I don't understand why you're using R/O water, so I'm not claiming to have a better idea. But, it's use seems to be creating a condition which virtually negates BB in your system. I'd probably revisit that whole decision process rather than trying to add multiple chemicals and additives to "fix" it.

In the meantime, I'd change the feeding regimen to be small amounts daily or every other day rather than large feedings once or twice per week.
 
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