PH Increasing Over Time

[Tank1]

What causes the PH value of the water in an aquarium to increase over time?

For example, I have two aquariums, one newer, one older. Each has aquarium gravel, one colored, one natural. Each has plastic plants and each has different decor such as formed resin or other types of decor rock like rainbow rock or lava rock but neither has the same decor for long. I have multiple sets of decor and I switch them out with each monthly service. Each tank gets a 50% water change, both are light to moderately loaded with mixed types of community fish. The PH coming out of the tap here is 7-5-7.6. The PH levels slowly creep up over time to levels as high as 8.2-8.3 which eventually kills the fish. In the larger tank, a 55 gallon, I've taken to using water softening pillows and that seems to be doing the job there. In the smaller/newer tank, I'd been slowly losing fish and it had slipped my mind to test the PH but it is now clear to me that I need to check it at least monthly. To lower the PH in the smaller tank, I did a series of water changes. I'd remove some, refill it with new water, then repeat slowly over the course of a few hours in an effort to not put the remaining fish into shock. That seems to have done the trick. The fish now look and act better and their appetites have returned. PH was 7.7 when all the work was done. GH test out of the tap shows moderately hard water but not extreme.

I'd like to figure out why the PH rises slowly as opposed to dropping slowly. Can I assume that there are elements in my water source that are slowly increasing hardness as they dissolve?

 

[gwand]

What causes the PH value of the water in an aquarium to increase over time?

For example, I have two aquariums, one newer, one older. Each has aquarium gravel, one colored, one natural. Each has plastic plants and each has different decor such as formed resin or other types of decor rock like rainbow rock or lava rock but neither has the same decor for long. I have multiple sets of decor and I switch them out with each monthly service. Each tank gets a 50% water change, both are light to moderately loaded with mixed types of community fish. The PH coming out of the tap here is 7-5-7.6. The PH levels slowly creep up over time to levels as high as 8.2-8.3 which eventually kills the fish. In the larger tank, a 55 gallon, I've taken to using water softening pillows and that seems to be doing the job there. In the smaller/newer tank, I'd been slowly losing fish and it had slipped my mind to test the PH but it is now clear to me that I need to check it at least monthly. To lower the PH in the smaller tank, I did a series of water changes. I'd remove some, refill it with new water, then repeat slowly over the course of a few hours in an effort to not put the remaining fish into shock. That seems to have done the trick. The fish now look and act better and their appetites have returned. PH was 7.7 when all the work was done. GH test out of the tap shows moderately hard water but not extreme.

I'd like to figure out why the PH rises slowly as opposed to dropping slowly. Can I assume that there are elements in my water source that are slowly increasing hardness as they dissolve?

The pH of tap water can increase over time when left out primarily due to the outgassing of carbon dioxide (CO2) from the water. Tap water usually contains dissolved CO2, which helps keep the pH slightly acidic. When water is exposed to air, especially if it's aerated or stirred, the CO2 gas can escape into the atmosphere. As CO2 leaves the water, the concentration of carbonate ions relative to bicarbonate ions increases, making the water less acidic and causing the pH to rise. This process is more noticeable in softer water where there are fewer buffering minerals to stabilize the pH.

 

[Colin_T]

What sort of fish do you keep?
A pH of 8.2-8.3 doesn't normally kill fish.

Have the filters been cycled (developed colonies of beneficial filter bacteria that keep ammonia and nitrite at 0ppm)?

What sort of filters are on the tanks?

How often and how do you clean the filters?

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Something in the tank/s is causing the pH to go up. It's usually rocks or gravel. Take a couple of handfuls of gravel and put it in a bucket of tap water. Put the rocks in another bucket of tap water. Have a third bucket of tap water sitting next to the other 2 buckets but don't have anything in it except water.

Monitor the pH on all 3 buckets and see if any rise over a week or two. If it does, then whatever is in the bucket is causing the pH to go up.

--------------------

Water softeners on taps are usually ion exchange units and these replace calcium with sodium. Sodium is bad for freshwater fishes if they are exposed to high concentrations or for long periods of time.

What is the GH (general hardness) and KH (carbonate hardness) of your water supply?
This information can usually be obtained from your water supply company's website (Water Analysis Report) or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).

Depending on what the GH of your water is, will determine what fish you should keep.

Angelfish, discus, most tetras, most barbs, Bettas, gouramis, rasbora, Corydoras and small species of suckermouth catfish all occur in soft water (GH below 150ppm) and a pH below 7.0.

Livebearers (guppies, platies, swordtails, mollies), rainbowfish and goldfish occur in medium hard water with a GH around 200-250ppm and a pH above 7.0.

If you have very hard water (GH above 300ppm) then look at African Rift Lake cichlids, or use distilled or reverse osmosis water to reduce the GH and keep fishes from softer water.

 

[sharkweek178]

The pH of tap water can increase over time when left out primarily due to the outgassing of carbon dioxide (CO2) from the water. Tap water usually contains dissolved CO2, which helps keep the pH slightly acidic. When water is exposed to air, especially if it's aerated or stirred, the CO2 gas can escape into the atmosphere. As CO2 leaves the water, the concentration of carbonate ions (CO3^2-) relative to bicarbonate ions (HCO3^-) increases, making the water less acidic and causing the pH to rise. This process is more noticeable in softer water where there are fewer buffering minerals to stabilize the pH.

If this is the case for the OP, then a schedule of frequent large water changes would stabilize the pH. That's just a good idea in general.

 

[Tank1]

What sort of fish do you keep?
A pH of 8.2-8.3 doesn't normally kill fish.

Have the filters been cycled (developed colonies of beneficial filter bacteria that keep ammonia and nitrite at 0ppm)?

What sort of filters are on the tanks?

How often and how do you clean the filters?

--------------------

Something in the tank/s is causing the pH to go up. It's usually rocks or gravel. Take a couple of handfuls of gravel and put it in a bucket of tap water. Put the rocks in another bucket of tap water. Have a third bucket of tap water sitting next to the other 2 buckets but don't have anything in it except water.

Monitor the pH on all 3 buckets and see if any rise over a week or two. If it does, then whatever is in the bucket is causing the pH to go up.

--------------------

Water softeners on taps are usually ion exchange units and these replace calcium with sodium. Sodium is bad for freshwater fishes if they are exposed to high concentrations or for long periods of time.

What is the GH (general hardness) and KH (carbonate hardness) of your water supply?
This information can usually be obtained from your water supply company's website (Water Analysis Report) or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).

Depending on what the GH of your water is, will determine what fish you should keep.

Angelfish, discus, most tetras, most barbs, Bettas, gouramis, rasbora, Corydoras and small species of suckermouth catfish all occur in soft water (GH below 150ppm) and a pH below 7.0.

Livebearers (guppies, platies, swordtails, mollies), rainbowfish and goldfish occur in medium hard water with a GH around 200-250ppm and a pH above 7.0.

If you have very hard water (GH above 300ppm) then look at African Rift Lake cichlids, or use distilled or reverse osmosis water to reduce the GH and keep fishes from softer water.

The 55 gallon glass hexagon has a HOB Marineland Penguin power filter and an air stone for added circulation due to the depth. The smaller tank is a 29 gallon acrylic Uniquarium. The 55 has been running for decades, the Uni is about 2 years old. Granted, this is the first time I've experienced persistent fish loss in the newer aquarium so I guess I cannot really complain.

Thanks to everyone for your input. For the time being, I will simply do larger water changes on the smaller tank to see if I can maintain a PH value of below 8.0. If not, then it get's the soft water pillow treatment.

As far as fish, I've been keeping fish for decades. The fish we see in retail shops are primarily farm raised and not necessarily raised in like-nature conditions. IME, this makes them more tolerant to a wider spread of water parameters. In other words, fish are more tolerant than what I've read about them in books, wild caught fish being the exception. That's not to say that I am a rebel rule breaker. I try to keep the environment within parameters for what I know they can handle.

 

[gwand]

The 55 gallon glass hexagon has a HOB Marineland Penguin power filter and an air stone for added circulation due to the depth. The smaller tank is a 29 gallon acrylic Uniquarium. The 55 has been running for decades, the Uni is about 2 years old. Granted, this is the first time I've experienced persistent fish loss in the newer aquarium so I guess I cannot really complain.

Thanks to everyone for your input. For the time being, I will simply do larger water changes on the smaller tank to see if I can maintain a PH value of below 8.0. If not, then it get's the soft water pillow treatment.

As far as fish, I've been keeping fish for decades. The fish we see in retail shops are primarily farm raised and not necessarily raised in like-nature conditions. IME, this makes them more tolerant to a wider spread of water parameters. In other words, fish are more tolerant than what I've read about them in books, wild caught fish being the exception. That's not to say that I am a rebel rule breaker. I try to keep the environment within parameters for what I know they can handle.

I guess the soft water pillow treatment will remove calcium and magnesium ions dropping your GH. What do you anticipate will be the magnitude in the drop of GH? I’m not familiar with the pillow.

 

[Tank1]

I guess the soft water pillow treatment will remove calcium and magnesium ions dropping your GH. What do you anticipate will be the magnitude in the drop of GH? I’m not familiar with the pillow.

Good question. I've been using two pillows in the 55 for a year or two now and the effect has been able to keep the PH value just below 8.0. Otherwise it hits 8.3-8.4. I will test GH/KH of the 55 soon and share the results here.

 

[Colin_T]

What sort of fish do you keep?
Some fish are fine in water with a high pH and a lot of minerals.

 

[Tank1]

What sort of fish do you keep?
Some fish are fine in water with a high pH and a lot of minerals.

Between both tanks: glow tetras, neon tetras, angelfish, cory cats, red-tail shark

 

[Fishfunn]

7-5-7.6. The PH levels slowly creep up over time to levels as high as 8.2-8.3 which eventually kills the fish. In the larger tank, a 55 gallon, I've taken to using water softening pillows and that seems to be

In all my years of having aquariums, I never had water get more alkaline as you are experiencing. My water gets more acidic over time. My tap water pH is like yours, and my GH and KH are moderate. I decorate with live plants, so I don't use plastic, but I dont think that would matter too much.

I'd like to figure out why the PH rises slowly as opposed to dropping slowly. Can I assume that there are elements in my water source that are slowly increasing hardness as they dissolve?

Maybe the gravel rock, or other decor is raising your pH. Calcium carbonate would raise it.

 

[MuddyWaters]

I have multiple sets of decor and I switch them out with each monthly service

this is a great idea!! Keep it fresh

 

[GaryE]

As far as fish, I've been keeping fish for decades. The fish we see in retail shops are primarily farm raised and not necessarily raised in like-nature conditions. IME, this makes them more tolerant to a wider spread of water parameters. In other words, fish are more tolerant than what I've read about them in books, wild caught fish being the exception. That's not to say that I am a rebel rule breaker. I try to keep the environment within parameters for what I know they can handle.

Most farms are in southeast Asia, and make a point of raising the fish they sell in the conditions that will grow them quickly. That means using conditions as close to their natural habitats as possible. When there was still a US based farming system, there was a lot of experimentation with raising fish in harder water than in nature, and it led to some successful selection for fish that could adapt quickly. Those days are long gone, partly because Asian farms with easy access to very soft water could raise their fish faster and more cheaply.
The common fish in the hobby are the ones that are tolerant of a wider range of water. It has nothing to do with adaptation to captivity over generations. That''s one of our myths of convenience.

All your fish are old timers in the hobby, and became that way because they could adapt right from the wild. It would be more interesting to see what the hardness of the water is doing, as pH isn't that important. It's a secondary reading.

 

[Fishfunn]

Many years ago, I used to always run carbon in my filters. I remembered that carbon used to raise the pH of my water, so I stopped using it. Since I stopped using carbon, my pH has never raised again.

 

[sharkweek178]

Most farms are in southeast Asia, and make a point of raising the fish they sell in the conditions that will grow them quickly. That means using conditions as close to their natural habitats as possible. When there was still a US based farming system, there was a lot of experimentation with raising fish in harder water than in nature, and it led to some successful selection for fish that could adapt quickly. Those days are long gone, partly because Asian farms with easy access to very soft water could raise their fish faster and more cheaply.
The common fish in the hobby are the ones that are tolerant of a wider range of water. It has nothing to do with adaptation to captivity over generations. That''s one of our myths of convenience.

All your fish are old timers in the hobby, and became that way because they could adapt right from the wild. It would be more interesting to see what the hardness of the water is doing, as pH isn't that important. It's a secondary reading.

I just don't get this idea that people have that a few generations of breeding somehow overcomes millions of years of evolution.

 

[Tank1]

Update...

Ended up using water softener pillows to lower the hardness. GH and KH now 5-6. However, the ph is still high at 8.2, tested on a high range kit and mid range kit as a back-up.

The remaining angel has red streaks in it's face between the mouth and eyes and red lines at the base of it's fins. Sorry, I don't have images to share.