Mbuna tank sudden pH drop

[StevenF]

crushed coral is mainly calcium carbonate. in soft water it only dissolves if the PH is below 7. When it dissolves it pushes the PH up. Once PH reaches 7 it stops dissolving and the PH stops at about 7. Now the final PH of your water depends on everything in your water calcium carbonate is just one part of the PH. So the final PH will very a little pit. For example look at sea water. There is calcium dissolved in the water along with a lot of salts. Sea water has a PH of 8. instead of the fresh water PH of 7.

In my small 5 gallon tank one sea shell is all I need to maintain a PH of 7 and it takes about 1 year for it to dissolve away. Once it is almost gone I add another. The chemistry of calcium carbonate doesn't change over time. You shouldn't need a lot of it in the tank. A cup of it should work. The best place to put it is in the filter since all the water will pass through it in about 30minutes.

Another thing I forgot to mention was, during the pH drop, the water surface was loaded with bubbles. This whole thing was strange, I have been keeping African cichlids for about 15 years, never saw this and it all happened within a couple of hours.

Honestly this sounds like something like got in your water. If It floats in water and it you had a slight film of it on the surface that would stop gas exchange with the air and bubble would form. And if it gets in the fishes gills the fish would have a hard time getting the oxygen they need. the loss of gas exchange would also cause CO2 to increase which would lower PH.

Some time ago I read about one guys tank that suddenly went bad he lost fish and plants. In the end it was all traced back to his water pump which failed several days later. His pump had a sealed bearing with oil in it. The seal failed and a very small amount leaked out and he didn't see it. The oil got out and caused the problem Now most pumps in the hobby don't use oil instead they use a metal pin and use water as the lubricant. How he ended getting a pump with oil in it I don't know.

 

[Byron]

Dealing solely with the pH question... @Colin_T asked for the GH and KH of the source water, and this is the crux of the pH issue. If the GH is high as needed for rift lake fish, the KH will be similarly high and the pH will be basic. If the source water remains the same, pH "crashes" are unlikely, unless some other chemical additive or CO2 is being added.

It is easy enough to maintain a high GH/KH/pH. There are calcareous sand substrates, and there are rift lake mineral salts (note, mineral salts, not common sodium chloride salt). Shells, etc also help, but these will be inadequate on their own if the source water is low in GH/KH to begin with.

What is the GH and KH of the source water? And if you can measure these, of the tank water for comparison? The source (tap) water data should be available from your water authority, check their website.

Aquarists fixate over pH, but it is the GH/KH that really matters, and the pH will normally follow suit (there are always exceptions).

 

[gilpi]

Dealing solely with the pH question... @Colin_T asked for the GH and KH of the source water, and this is the crux of the pH issue. If the GH is high as needed for rift lake fish, the KH will be similarly high and the pH will be basic. If the source water remains the same, pH "crashes" are unlikely, unless some other chemical additive or CO2 is being added.

It is easy enough to maintain a high GH/KH/pH. There are calcareous sand substrates, and there are rift lake mineral salts (note, mineral salts, not common sodium chloride salt). Shells, etc also help, but these will be inadequate on their own if the source water is low in GH/KH to begin with.

What is the GH and KH of the source water? And if you can measure these, of the tank water for comparison? The source (tap) water data should be available from your water authority, check their website.

Aquarists fixate over pH, but it is the GH/KH that really matters, and the pH will normally follow suit (there are always exceptions).

I have no way of checking gh/kh at the moment, only pH. Nothing got in the tank, it's in the basement and only I go down there and it all happened in a matter of a couple of hours. I increased the surface movement and added some water mixed with baking soda to bring the pH up. Only thing I did was the water change the day prior. I had something similar happen once right after a water change not a day later.

 

[Byron]

I have no way of checking gh/kh at the moment, only pH. Nothing got in the tank, it's in the basement and only I go down there and it all happened in a matter of a couple of hours. I increased the surface movement and added some water mixed with baking soda to bring the pH up. Only thing I did was the water change the day prior. I had something similar happen once right after a water change not a day later.

We are guessing until we have the GH nd KH for the source water. This is quite likely the problem behind the pH. Can you get the data from your municipal water authority, their website or call them.

 

[gilpi]

We are guessing until we have the GH nd KH for the source water. This is quite likely the problem behind the pH. Can you get the data from your municipal water authority, their website or call them.

Almost next to impossible to do, the couple of times I got to speak with someone about this, the only thing they said is "we keep our pH neutral", I would have to just test the water coming out of the tap. In about 15 years this has only happened twice after a big (1/2 or more) water change.

 

[Colin_T]

Do they have a lifespan? In other words, the rocks and crushed coral and shells, do they have to be changed eventually?

They do dissolve slowly over time as they neutralise acids in the water. But they last years before they dissolve.

 

[itiwhetu]

If your base medium is correct and you do the correct size water changes the hardness and pH of the source water doesn't matter. In the natural world these lakes are refilled with rainwater.

 

[gilpi]

If your base medium is correct and you do the correct size water changes the hardness and pH of the source water doesn't matter. In the natural world these lakes are refilled with rainwater.

base medium??

 

[Colin_T]

base medium??

gravel or sand on bottom of aquarium

 

[itiwhetu]

base medium??

Substrate.

 

[Alice B]

Pick up a bottle of 5 in 1 test strips. Tetra used to offer KH/GH test kits but they were expensive and I'm not sure they still make them. 5 in 1 will give you KH and GH but the pH is hard to read accurately, I get a liquid high range Ph test. Test your source water before the water change and see if you are expecting trouble. And yes a sea shell, piece of holey rock, will help buffer the alkalinity.

 

[Byron]

Almost next to impossible to do, the couple of times I got to speak with someone about this, the only thing they said is "we keep our pH neutral", I would have to just test the water coming out of the tap. In about 15 years this has only happened twice after a big (1/2 or more) water change.

OK, this is even more reason to get the data on the GH/KH of the source (tap) wat6er, and to demand they tell you what they are adding to "keep the pH neutral." This is a public health issue, they are required (I assume it is the same in US as Canada) to make you aware of just what substances are in your water.

Areas that have soft acidic water, like mine, often add substances to raise the pH (but not the GH/KH, depending upon what they add). This too can cause issues, so you need to find out.

The bottom line is still the GH/KH. Rift lake fish must have moderately hard or harder water. And if the GH was up where it needs to be (12 dH roughly, or higher) the KH would likely be similar, and the pH would be basic and stable. It is not sounding as though this is the case here, and that is what needs to be sorted out.

 

[gilpi]

Look at where African Cichlids come from, they come from limestone filled lakes. Not Coral or the Ocean. These are freshwater fish living in lakes filled with limestone, which is why I fill my tanks with limestone.

 

[Deleted member 149562]

Something to consider is that your water company may have done some work in your neighbourhood or there might be a break in the neighbourhood pipework that has caused a sudden change in water chemistry

Your water company website should give you not just your current water chemistry according to your postal code but it should also give you details of everything from them flushing pipes to fixing repairs to alerts about breaks/leaks and if they are replacing pipework...all of which will cause fluctuations in water quality and chemistry.

 

[gilpi]

So looking back and moving forward, it doesn't hurt to keep some limestone rocks or any other buffering stuff in the tank and or adding a bit of baking soda with water changes. I have been relying on my tap water alone being a bit high on pH.