Help What can be causing my PH crashing to 4 in my tank?

Aldofish

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I've recently had an issue with ammonia spikes and it seems to have settled down with 50 water changes, but now my PH has crashed to 4. My tap water tests at 7 and the nitrate and nitrite in my tank are at zero. Anyone have any thoughts?
 

Salem

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What all is in the tank in terms of substrate, decor, plants, etc? Is the tank in the process of cycling?

If you have a kh/gh test you may want to use it to figure out those levels. KH is basically what keeps the ph stable and when its under 4 it can allow things to swing pretty drastically.
 
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Aldofish

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Salem said:
What all is in the tank in terms of substrate, decor, plants, etc? Is the tank in the process of cycling?

If you have a kh/gh test you may want to use it to figure out those levels. KH is basically what keeps the ph stable and when its under 4 it can allow things to swing pretty drastically.
Tank is over 4 years running. Substrate is a very light sand. Decor is heavy on the driftwood which has been in there for years. Lightly planted. KH is reading at about 100 ppm. Tank has been cycled for a long time. Changed the filter about 8 weeks ago but seeded it with all the media from the old one and added more as the new one had more basket capacity. I'm baffled
 

H Farnsworth

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Could a massive bacterial die off produce enough co2 to lower the pH? Ammonia is a base so that’s not it
 
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Aldofish

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It's a weird one, I have another tank that is showing a low pH but only slightly (about 6) but my water from the tap always reads 7

I should also say that there is no cross contamination I have separate kit for each tank

H Farnsworth said:
Could a massive bacterial die off produce enough co2 to lower the pH? Ammonia is a base so that’s not it
Not sure, I've lost three fish to this (all the Same species) and I can't work out what the problem is. I used carbon for the first time as it came with the new filter. I doubt that it's where the problems lies but I'm going to bin it tonight and replace it with other media
 

Cichlidude

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If your pH is really that low, there is a problem.

How pH affects Ammonia

While no ammonia in your tank is desirable it should be noted on what levels ammonia is considered an issue. Ammonia is a slow process for being dangerous to your fish. It is very important to know the pH of your water to determine how fast to proceed with its removal. The ammonia in the water, if left unchecked, can lead to ammonia stress and ammonia poisoning.

The common aquarium “ammonia” test measures the total ammonia, both ionized and un-ionized (Total Ammonia Nitrogen or TAN).

The chronic toxicity, where the ammonia kills slowly by a variety of mechanisms, is as follows:

  • 20 to 100 ppm of ammonia TAN at a pH of 6.0
  • 2 to 10 ppm of ammonia TAN at a pH of 7.0
  • 0.2 to 1 ppm of ammonia TAN at a pH of 8.0
(Of course these numbers will vary depending on where you look on the web)

Any pH between the above numbers you will have to make a linear interpolation. As you can see there is a 10X increase or decrease in toxicity between pH levels.

A pH of 6.5 will reduce the growth of beneficial bacteria by 90%. A pH of 6.0 will virtually stop beneficial bacteria from oxidizing ammonia to nitrate; hence ammonia may be on the rise.

Ammonia causes internal damage to the brain, organs, and central nervous system. The fish begins to hemorrhage internally and externally and eventually dies.

As you can see it’s a balancing act with pH and how fast your filter(s) can oxidize ammonia. It’s very important that your filter has good effective media that water can flow through all your media and not around your media. Looking at the above if your pH is closer to 8.0, ammonia is more chronic over time and should be handled very quickly. If your pH is at 7.0, low levels of ammonia are not as chronic.

So if you have a pH of 6.0 and you raise your pH to 7.0, the ammonia is now 10X more toxic. You can see what happens if your filter cannot oxidize the ammonia quickly. If your pH was 6.5 or lower your bacteria may not be ready to oxidize the ammonia rise quickly.

The natural progression to reduce ammonia is by changing water. So don’t forget your de-chlorinator.

However some dechlorinators are not the same and can cause issues.

Remember ammonia is toxic over days and weeks. Chlorine kills in hours.
 

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