GobyMaster11276
Fish Crazy
Don't get me wrong, I'm not new to the hobby or to altering pH. In the past, I used pH up and down to do this, but now I have been told that this is the wrong way to do it. So how am I supposed to do this now? Thanks.
How to alter pH
- Thread starter GobyMaster11276
- Start date
The reason not to use pH chemicals is two-fold. First, they may or may not work (or they may work initially but within 24 hours not work) because of the GH and KH. Second, all chemicals get inside fish and the fewer the better [I'll come back to this at the end]. There are better and safer methods to adjust parameters if it is absolutely essential to do so.
The pH is tied to the GH and KH. KH (carbonate hardness) acts as a buffer to prevent pH fluctuations. The higher the KH, the stronger the buffering capacity. So if you add acids to lower the pH, the high KH will prevent this, up to the point when the buffering capacity is reached, then the ph can literally plummet. The pH lowering chemicals may immediately reduce the pH, but within the next several hours the buffering ability of the KH will return it to where it was; such fluctuating pH is very hard on fish, and can even kill them. The extent all this occurs depends upon the GH/KH/pH of the source water, and other substances that may impact the parameters.
Natural biological processes will tend to acidify the water, lowering the pH, in any aquarium with fish. Here again, the extent of this is determined by the GH and KH. Other factors also enter the equation, such as natural buffers; calcareous rock or substrate will raise GH and KH and pH, while organic substances (wood, leaves, peat) can acidify the water and lower the pH. You can appreciate how these can be working against each other.
This can get very complicated. The first thing to ascertain is the GH, KH and pH of the source water. Then, decide where you want the GH and pH. Generally, softer water will be more acidic than basic, and harder water will be more basic--though not always. Fish tend to have preferences for harder water that is basic, or soft water than is acidic. There are exceptions, but this is very general. Some fish have wider tolerances than others. It is always easiest and safer to select fish suited to the source water. But if adjustment is necessary, all of the factors have to be considered.
I mentioned the chemicals and fish. Every substance added to the water in which the fish live will be taken into the fish, into the bloodstream and internal organs, either at the gills or by osmosis through the cells of the fish. This is why the relationship of fish to their aquatic environment is far more sensitive than that of terrestrial animals to air, and why fish are thus so vulnerable. At the very least, these substances can cause stress; but some can be deadly. Only substances absolutely essential should be added to tank water. Conditioners are essential, but everything else should be limited as much as possible. Some of these can directly affect this or that, but they may also interact and cause even greater problems. Think of it like medications for humans; individually they may be useful, but combined they may kill.
Byron.
The pH is tied to the GH and KH. KH (carbonate hardness) acts as a buffer to prevent pH fluctuations. The higher the KH, the stronger the buffering capacity. So if you add acids to lower the pH, the high KH will prevent this, up to the point when the buffering capacity is reached, then the ph can literally plummet. The pH lowering chemicals may immediately reduce the pH, but within the next several hours the buffering ability of the KH will return it to where it was; such fluctuating pH is very hard on fish, and can even kill them. The extent all this occurs depends upon the GH/KH/pH of the source water, and other substances that may impact the parameters.
Natural biological processes will tend to acidify the water, lowering the pH, in any aquarium with fish. Here again, the extent of this is determined by the GH and KH. Other factors also enter the equation, such as natural buffers; calcareous rock or substrate will raise GH and KH and pH, while organic substances (wood, leaves, peat) can acidify the water and lower the pH. You can appreciate how these can be working against each other.
This can get very complicated. The first thing to ascertain is the GH, KH and pH of the source water. Then, decide where you want the GH and pH. Generally, softer water will be more acidic than basic, and harder water will be more basic--though not always. Fish tend to have preferences for harder water that is basic, or soft water than is acidic. There are exceptions, but this is very general. Some fish have wider tolerances than others. It is always easiest and safer to select fish suited to the source water. But if adjustment is necessary, all of the factors have to be considered.
I mentioned the chemicals and fish. Every substance added to the water in which the fish live will be taken into the fish, into the bloodstream and internal organs, either at the gills or by osmosis through the cells of the fish. This is why the relationship of fish to their aquatic environment is far more sensitive than that of terrestrial animals to air, and why fish are thus so vulnerable. At the very least, these substances can cause stress; but some can be deadly. Only substances absolutely essential should be added to tank water. Conditioners are essential, but everything else should be limited as much as possible. Some of these can directly affect this or that, but they may also interact and cause even greater problems. Think of it like medications for humans; individually they may be useful, but combined they may kill.
Byron.
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To give you a short answer: the pH of your tank mainly depends on your KH. To lower your pH you need to lower your KH.
GH is irrelevant. pH of of your Tap water is irreleavant too, because it will change in our tank. Most of the times water suppliers keep it artificially high to prevent corrosion of the pipes.
GH is irrelevant. pH of of your Tap water is irreleavant too, because it will change in our tank. Most of the times water suppliers keep it artificially high to prevent corrosion of the pipes.
OP
OP
GobyMaster11276
Fish Crazy
My pH is at 7.8 and still going up, so I guess my kH is too high? What do you think I should do?
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Hi GobyMaster1127:
I agree with Byron that the ph-altering chemicals are not a good idea.
I have very hard well water with a ph of nearly 8.0. Most of the time it's just fine; I keep species that either tolerate or prefer rock water. In one of my tanks, though, I maintain a lower kh (and therefore ph) by diluting my tap water with distilled water (I have a home distiller) at a very specific ratio. If you have to lower the ph in your tank, then you might consider using distilled or RO water in that way. Otherwise, I think working with the source water you have and choosing suitable stock for it is probably the way to go.
I agree with Byron that the ph-altering chemicals are not a good idea.
I have very hard well water with a ph of nearly 8.0. Most of the time it's just fine; I keep species that either tolerate or prefer rock water. In one of my tanks, though, I maintain a lower kh (and therefore ph) by diluting my tap water with distilled water (I have a home distiller) at a very specific ratio. If you have to lower the ph in your tank, then you might consider using distilled or RO water in that way. Otherwise, I think working with the source water you have and choosing suitable stock for it is probably the way to go.
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The pH rising in the aquarium is due to something that is targeting it, not because of the KH. The KH works to keep it at the same level. I'll come back to this after a brief explanation.
The pH in the aquarium starts out the same as the source water pH. Once in the aquarium, various factors affect it. First, organic processes (fish excrement decomposing primarily, along with any organics from wood, leaves decomposing, peat, etc) produce carbonic acid and CO2, and the pH will naturally lower as the acids accumulate. The extent to which this occurs (the lowering pH) depends upon factors such as the buffering capability of the KH, the fish load, feeding, organic substances, and other factors that will target the GH/KH/pH. In my tanks, with basically no KH, the pH lowers quite a bit, but somewhat different levels in my 8 tanks. The point here is that each tank is a unique biological system, and various factors may play out differently.
To the targeting. If there is a calcareous substance (primarily calcium and magnesium) such as calcareous rock or the substrate composed of say crushed limestone, coral, marble, aragonite, dolomite and similar, this will increase the mineral content which in turn raises GH, KH and pH.
So you have the initial GH/KH/pH of the source water, plus the acidifying properties, plus any targeting substances, and all these factors determine what will occur with respect to the parameters.
So the pH will either stay at the level of the source water if the KH is high enough to buffer it, or it will lower if the organics surpass the buffering capacity, or it will rise if calcareous substances are sufficient to override the previous two aspects. So you should look at any rock, or possibly the substrate material, for the explanation of the pH rising.
One last important point. If you are comparing the tank water pH to the source water pH, and the source water is tap water, there can be a lot of dissolved CO2 in the tap water, and this can result in a lower pH reading initially. You need to ensure any CO2 is out-gassed before testing tap water for pH. Let some tap water sit out 24 hours, or agitate it very briskly for a few minutes; then test pH. This should give you a more accurate reading. You may also be able to confirm this with the water authority, check their website for water data which might include GH, KH and pH. If after doing this you find the tank pH still higher, it is likely due to something in the tank that is adding mineral to the water.
Byron.
@Byron I don't agree with the overall message your are sending here or I missunderstand you.
People too much focus on pH, while KH (and GH) is the import number for your fish
pH directly depends on KH in the tank. If KH is right pH will move to the desired values too. And having water with a very low KH (below 2) is very risky for your fish as the pH is not well buffered anymore and can fluctuat heavily.
@GobyMaster11276
Important for the well beeing of your fish are stable parameters. And having the numbers right to the digit behind the point is not import. If you change your values do it slowly.
To reduce KH you need to add water without or a very low KH. Usually one would use reverse osmosis water. Rain water can also be a good source, but this is some disputed topic to how pure or contaminated it can be.
People too much focus on pH, while KH (and GH) is the import number for your fish
pH directly depends on KH in the tank. If KH is right pH will move to the desired values too. And having water with a very low KH (below 2) is very risky for your fish as the pH is not well buffered anymore and can fluctuat heavily.@GobyMaster11276
Important for the well beeing of your fish are stable parameters. And having the numbers right to the digit behind the point is not import. If you change your values do it slowly.
To reduce KH you need to add water without or a very low KH. Usually one would use reverse osmosis water. Rain water can also be a good source, but this is some disputed topic to how pure or contaminated it can be.
I think we are largely in agreement (hobby5). I was attempting to explain simply why the OP is seeing the numbers. I wasn't suggesting adjustment. The OP says the pH is rising in the aquarium, and I wanted to explain the possible reasons.
We don't know the GH, KH and pH of the source water. Having these numbers might explain more.
I agree (and so often say it) that GH is the most important of the three for fish.
We don't know the GH, KH and pH of the source water. Having these numbers might explain more.
I agree (and so often say it) that GH is the most important of the three for fish.
For PH changes we need to know all of your water parameters (nitrate, GH, KH, and PH ) for the tap and tank. We also need to know everything that has happened prior, what fertilizers or water treatments were added. All of these parameters are related Sometimes a ph change has nothing to do with KH or GH.
Can you elaborate on this a little more please? Why do we need to know Nitrate? Why GH?
A pH change never has anything to do with GH. (Magnesium and Calcium ions have no direct influence on pH.)
Imho the only relevant number for pH is KH as long as KH is present at all. Of course you can change the pH somewhat by CO2 fertilization and water agitation, but the result will always depend on the existing KH.
A glass of fertilized water sitting on shelf in a dark room will have a stable PH readin. However if you add a plant and light the PH can potentially change. For example my tank was deficient in sulfates. To correct that I added calcium sulfate. in the morning just before the lights turned on the PH was about 6.5. Just before the lights turned off the PH was 9. 3 hours after lights turned off the PH was back down to about 7. What was happening was the plants were consuming the sulfate and leaving the Calciu behine. The calcium sulfate was converted to Calcium hydroxide (a strong base) which pushed PH up. When the lights went off the hydroxide reacted with CO2 from the air to form Calcium carbonate. For my particular problem there were two possible solutions, Add CO2 or turn down the liights. For now I have turned down the lights.
Another issue I have see is when I dose the tank with KNO3 nitrate fertilizer and KPO4 phosphate fertilizer I would get more potassium than needed which again turns into a hydroxide and pushes PH up. The solutions for this issue is to use less fertilizer or use alternative fertilizers (I have done both).
The key pointy is that an aquarium is a dynamic place and water parameters can change faster than we believe possible. Knowing all the tank parameters and what is going into the tank is often necessary to know why PH is going up.
@StevenF
I totally agree that plants can change the pH, but this is a special case rarely observed. And again measuring GH and nitrates give you no information here. The main determinat of pH in your tank is KH. Only if those two don't correspond like expected, one needs to investigate further. And this will always discover an unhealthy situation you want to resolve to normal again.
Moreover, I don't think your explanations fit your observations. Plants will never turn those salts into hydroxides.
Imho, what you observed is called biogenic decalcification. After adding fertilizer the limiting factor of plant growth in your tank had been CO2 and your plants started to use carbonates. This very well corresponds with your observations of the pH change following the day-night-cycle.
I totally agree that plants can change the pH, but this is a special case rarely observed. And again measuring GH and nitrates give you no information here. The main determinat of pH in your tank is KH. Only if those two don't correspond like expected, one needs to investigate further. And this will always discover an unhealthy situation you want to resolve to normal again.
Moreover, I don't think your explanations fit your observations. Plants will never turn those salts into hydroxides.
Imho, what you observed is called biogenic decalcification. After adding fertilizer the limiting factor of plant growth in your tank had been CO2 and your plants started to use carbonates. This very well corresponds with your observations of the pH change following the day-night-cycle.
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