What's making the the ph keep going down

[concentration]

Hello I had a problem with low pH recently which I didn't had before ,

Tank size 28L
5 guppies
Current tank water Par as below
Ammo min to 0.1
No2 Min to 0.1
No3 below 10
pH =6 below slightly below ( my tester only can go as low as 6)

Fishes look fine and health , water is clear

Water source par as below
Ammo no2 no3 zero
pH 7.7
GH low Kh very very low

Product or stuff I have in tank

A hang on filter
Seachem prime
Seachem stability
Seachem matrix ( which is in the filter )
Seachem denitrate( inside a small diy in water reactor )
I current use denitrate as substance as well
3 air stone

Just in case it's the dirt or sth that keep pushing the ph down , at one time I remove and clean everything except the denitrate as substance but ph still keeobgoing down fast

In one time I use baking soda to raise the ph back to 7.8 and just over night it drop all the way back to 6.5

While low Kh could mean insufficient buffering, I am wondering why the ph keep going down do fast

No dead fishes no dead plant and if it's about some dirt or leftover food , should also be reflected in ammo or no2 figure

Any idea what keep pushing it down ?

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[Byron]

The low GH and KH is why your pH is and will continue to be acidic. I'll explain.

In any aquarium, organics build up from fish excrement primarily but any organic matter. As organics are broken down by various bacteria, CO2 (carbon dioxide) is produced. The CO2 causes carbonic acid, and the pH thus lowers accordingly. The rate at which it does this, or if it does at all, is determined by the carbonate hardness (KH, or Alkalinity) which acts like a "buffer," and this is in turn tied to the GH usually. So simply put, the harder the water (more dissolved mineral), the more buffering to prevent the pH from fluctuating. It will remain at some level once all this has stabilized. As the organics increase, the longer the aquarium is running, the greater the effect which is why at first you didn't notice it much but do now. This is very simply put, but it is what is going on.

The tap water pH of 7.7 may be due to some additive by the water authority. I have this here in Vancouver, as we have very soft water (near zero GH and KH) and they add soda ash to raise the pH. This is temporary, and in an aquarium it dissipates out fairly quickly and the pH remains stable at some acidic level. I have tanks with pH 6.4, others at pH 5. It all depends upon various biological factors within each individual tank.

You have two options. The simplest is to maintain soft water fish. Your source water is ideal for most all of the fish from South America and SE Asia. Livebearers come from Central America where the water is moderately hard with a basic pH (above 7). You can take steps to increase the GH/KH/pH for livebearers. Adjusting water parameters is a complex topic I won't get into here, but it is possible.

Temporary measures like using baking soda are not recommended. They are temporary, so this means the pH is fluctuating back and forth, and this is much harder on fish than a stable pH even if slightly out of their preferred range. Guppies are able to tolerate this better than other livebearers, but it is still not good for them.

By the way, you do not need to be using Stability regularly. It is no benefit, and while not a significant detriment it is not necessary, and the less substances we add to an aquarium the better because there is less to go wrong and more likely the natural processes will be stable and normal.

Byron.

 

[StevenF]

One possible solution you might try is to put a sea shell in the water. When the PH drops it will start to dissolve and that will push the PH up. The calcium carbonate in the shell stops dissolving at a PH of 7. So it won't push the PH higher than 7. If your PH stays between 6 and 7 it should not have big impact on GH.

Water has a lot of chemical compounds in it. Some are acidic. Others are basic. The ratio of bases to acids determine your PH. If plant are present in the tank they cane consume potassium, calcium nd magnesium. If this happens PH will fall. In other cases plants could consume a lot oa chlorides, sulfates or carbonate ions. It that happens the PH could go up.Normally PH changes due to plants are small but sometimes they are not.

 

[concentration]

Do anyone have any idea what kind of plant may increase ph ?

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[StevenF]

It isn't the plant that causes the change it is the chemistry change that occurs when plants are growing that causes PH to change. All plants require the same nutrients. They will make the water softer. But the PH can go high or low depending on the chemistry of the water.

So in short if you set up to identical tank with the same plants and and same lights, heater, and filter the PH may go up or down depending on the water chemistry of each tank. If one is a soft water tank for soft water fish its PH will probably be different then the other if the second one is a hard water tank.

Adding a sea shell to a tank as i mentioned earlier is an easy safe solution. Try it. It will keep your PH at 7. If you decide in the future that you want low PH getting there might be as simple as removing the shell from the tank. The only way I know how to prevent PH from going up is to reduce light levels.

 

[Byron]

This is not likely a plant-related issue. With a "very, very low" KH, and a "low" GH, there is no buffering and the pH will naturally lower as the water becomes acidic.

What is the number for the GH and pH? And have you checked with the water authority to see if they add any pH stuff?

And what fish species? Soft water fish will be fine, and all this attempting to raise the pH will harm them.

Byron.

 

[concentration]

I didn't ask authority for the ph if they have add something temp boost up the ph , but I have take out a small pool of water and leave it for over a week and the ph is still over 7.2 so it seems the source does have a ph of over 7

How fast can water turn acid naturely? I understand it will turn acid depending on the fishes plant and many other thing but sometime it drop by 1.5 or close to 2 over night is too fast , specially it isn't the case before (subject to the same water ) recently I notice the speed of falling does varies , sometime it drop by almost two while something only about 0.5 ( no water change in between) GH is 50(not sure in what unit ) and Kh is 10

Do you think I can add seashell or limestone to balance it ?

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[concentration]

This is not likely a plant-related issue. With a "very, very low" KH, and a "low" GH, there is no buffering and the pH will naturally lower as the water becomes acidic.

What is the number for the GH and pH? And have you checked with the water authority to see if they add any pH stuff?

And what fish species? Soft water fish will be fine, and all this attempting to raise the pH will harm them.

Byron.

Oh by the way I am having guppies , yes they are Not perfect in soft water but I have them already for 8 months and I do not want to give it away , ,maybe I can add something nature to help them with GH and Kh ?


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[StevenF]

In order for the PH to change something has to be added to the water or removed. Plant, bacteria, animals are the only things in the aquarium that can do it. By themselves GH and KH will not cause a change. And we have to adapt.

GH is 50(not sure in what unit ) and Kh is 10

It is important that we know the units. PPM or degrees. If it is degrees then the GH is 890ppm (unlikely) and the KH would be 178ppm. If it is in ppm a GH of 50 is very soft water. Was the KH measured with the same test kit or do these numbers come from a water quality report?

If your water is 890ppm GH and 278ppm KH the only suggestion I have is to not use the water. I have never head of tap water being that hard.

If the numbers are in ppm then the (likely) then plant absorbing potassium could easily drop the ph. Then there are two possible solutions add a sea shell to neutralize the acids and or start using a fertilizers. Water with a GH of 50 is likely deficient in some nutrient which could lead to algae issues in the future. This solution allows you to stock many of the most common soft water fish available. For your guppies

The other possible cause is an acid being added to the water, Organics could do it but a 2 point PH drop overnight just sounds to fast organic buildup and decay. If plants are consuming potassium from potassium sulfate then the sulfate could be covered to hydrogen sulfide which is ver acidic.

Now we could try to select fish to handle the low PH but swings in PH overnight is likely very bad for most fish. but such large changes in PH overnight are not going to be good for any fish. regardless of their tolerance.

My water is typically around 75ppm GH and the KH is typically between 20 to 40 ppm. I have snail shells in the water. PH stays between 6 and 7 with it most often being very close to 7. Now the shells will probably add some GH to your water but with soft water it is unlikely to be much.

for the Guppies you currently have I would consider using a GH booster to increase your water hardness to better mach the water to the needs of the fish.

 

[concentration]

I see thank you , yes it probably is ppm and I agree that the swing is bad for any fish given the water source ph difference, I do have a GH booster in liquid but doesn't like the idea I have to keep adding it , let me try with shell or some lime and get back to you guys how the ph GH and Kh later , thank you

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[Byron]

I didn't ask authority for the ph if they have add something temp boost up the ph , but I have take out a small pool of water and leave it for over a week and the ph is still over 7.2 so it seems the source does have a ph of over 7

This still doesn't answer the question. Check the water authority's website to see if they are treating the water to raise pH. The water sitting overnight tells us nothing about this, but it does tell us that the pH at that time is 7.2, but not "why." With no buffering (from the very low KH and low GH) the pH will naturally lower due to organics.

How fast can water turn acid naturally? I understand it will turn acid depending on the fishes plant and many other thing but sometime it drop by 1.5 or close to 2 over night is too fast , specially it isn't the case before (subject to the same water ) recently I notice the speed of falling does varies , sometime it drop by almost two while something only about 0.5 ( no water change in between) GH is 50(not sure in what unit ) and Kh is 10

None of this is at all surprising or unusual. You are however getting things a bit confused. The lowering of the pH by 0.5 during several days is very likely natural due to the organics. This is not at all unusual when there is no buffering present. The change of 1.5 or 2 in pH "overnight" is also not at all unusual, because this is most likely the pH in the aquarium stabilizing after the addition of fresh water, when the added water of pH 7.2 with no buffering is mixed in with the more stable pH of the aquarium water. Now, I am assuming this 1.5 to 2 change is between the tap water pH of 7 or 7.2 and the tank, after a water change.

As you have guppies which are livebearers, they will be better with more mineral in the water (higher GH, and basic pH meaning 7.0 or above), and Steven has suggested methods to probably achieve this.

Byron.