# Need help with pH swing pls



## Fish rookie (May 21, 2012)

Hi,

I have noticed that my tank's pH has quite a big swing (from 7.6 to 6.8 and back between day and night).

Usually in the middle of the day after my CO2 has run for about a couple hours the pH will drop to around 6.8 and it will stay there. At night I stop my CO2 and put an airstone in the tank and when I check the pH in the morning it is about 7.6.

When I change my water I usually add alkaline buffer and the PH is a bit higher than 7.6 (may be 7.8) before I add water into my tank. 

If I keep my Co2 running all day long (not off at night) and only put an airstone in the tank after light out do you think it will help to keep the pH more steady?

My fish are still alive but I just realized that the angel fish I got from IPU were actually kept in water with pH 7-7.5 and KG of 4-5. 

The angle fish must be going through a lot of stress with that much pH swing during the day...what should I do?

Most of the plants in my tank prefer a lower pH which is why I do not want to keep the pH too high.

Can I dose perhaps 1/8 of a teaspoon of alkaline buffer whenever I dose my EI (which is daily except the day when I do my wc) to help buffering the swing.

Right now I am changing about 30-50% of water every 4-5 days and I add alkaline buffer and equilibrium when I do. But I do nto add any alkaline buffer excpet during water change.


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## Rastapus (Apr 21, 2010)

Fish Rookie,
The Alkaline buffer will increase your pH and the CO2 will lower it. What are your hardness levels? Are you using a DIY CO2 or pressurized cylinder? FYI a GH measurement of 4 degrees with the angels is still considered soft water. Without more info it sounds as though your CO2 additions are not sufficient to lower your pH to the desired level you are looking for. Please provide more water test info and we can go from there.


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## coppercloud (Apr 14, 2012)

iheard that oxyagen razes ph so if the co2 is off and the airstone is on it would go from low in the day cuz of the co2 and high at night cuz of the oxygen


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## Fish rookie (May 21, 2012)

Thank you very much.
I am using DIY Co2. 2 bottles, connected to a Nova internal filter (I think that is what it is called. I got that from IPU and it was about $25, with a sponge housed insode a black casing below a powerhead) air intake then come through a spray bar. I also have a powerhead with a propeller on top of the spray bar. At night I turned this filter off and added an airstone.
I just tested my Ph and it is now around 7 when it was around 7.4 this morning right after I started Co2.
I lend my KH/GH test kit to someone but will get it back this evening.
My GH and KH are usually around 4-6.
Angelo was very patient and spent lots of time to explain to me at IPU(Richmond) that I should try to keep my Ph around 7 to 7.5 not 6.6 or so because the fish I got were not caught in the wild and he asked me to test my pH and harness for 5 days 3 times a day then bring it to him for more advise.
I was going to buy some ram to go with the angle fish but decided to hold off until I have this sorted out. I only purchased some oto and cory dora and they seem to be fine today. I did spend a lto fo time to acclimatize them before I put them in, but with the big swing I am worried eventually they will get sick.
Thank you for all your help.


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## 2wheelsx2 (Apr 21, 2010)

pH swings due to CO2 are inconsequential as long as it goes back up. When you add CO2 gas to the water, you're creating carbonic acid, which of course would lower you pH. When you discuss pH with people who do not know your situation you have to tell them up front that you're injecting CO2 otherwise you'll get bad/wrong advice. The assumption with most people is that your tank is a fish only tank, or at most, have a few plants. The pH swings are why some people choose to use pH controllers to turn their pressurized CO2 systems on and off. The lower pH would indicate sufficient CO2 and the pH controller would then turn the CO2 off.

This is another disadvantage of DIY CO2, is that you cannot control the concentration. You are at the mercy of the yeast's ability to convert the sugar to CO2.


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## Fish rookie (May 21, 2012)

2wheelsx2 said:


> pH swings due to CO2 are inconsequential as long as it goes back up. When you add CO2 gas to the water, you're creating carbonic acid, which of course would lower you pH. When you discuss pH with people who do not know your situation you have to tell them up front that you're injecting CO2 otherwise you'll get bad/wrong advice. The assumption with most people is that your tank is a fish only tank, or at most, have a few plants. The pH swings are why some people choose to use pH controllers to turn their pressurized CO2 systems on and off. The lower pH would indicate sufficient CO2 and the pH controller would then turn the CO2 off.
> 
> This is another disadvantage of DIY CO2, is that you cannot control the concentration. You are at the mercy of the yeast's ability to convert the sugar to CO2.


Thank you for your reply.
If I have enough buffer, can the Ca ion in the water stop the carbonic acid from bringing the pH too low?
If I add say 1/8 of a teaspoon of CaCO3 into my water in the morning daily before I start my CO2, can they help to buffer the pH?
My pH never drops to like 5 or something crazy like that, but it is still a big swing for more than .5 in a day, is it?
Or can I just let the CO2 run day and night and just add an airstone at night to make sure there is enough O2 at night?
I think for the Co2 to start in the morning it takes awhile which is why the Ph started at 7.6 then goes back to around 7 then 6.8 after noon time. If I keep the Co2 running may be the Co2 does nto need to take so much time to start and once I remove the airstone it will become more consistent...
I am pulling my hair out....what should I do?


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## 2wheelsx2 (Apr 21, 2010)

The simplest way to continuously buffer your tank when running CO2 is to have a bag of crushed coral in your filter. Dropping 0.5 when injecting CO2 is pretty harmless. Many people set their pH controllers to shut the CO2 off at 5.5 on plantedtank.net.

Another way to do it is to use a substrate that buffers the pH like ADA AS or Eco-complete. When using inert substrates, you have to provide the buffers. Your method will work, but what about when you forget or when you go away on vacation?


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## Fish rookie (May 21, 2012)

I just tested my ph one more time and it is again at 6.5, so it has not dropped any more.
My KH is 7 and my GH is 3. 
So basically, this morning right after light was on (10am), pH was about 7.5 or so.
Around noon it dropped to 7. 
2 hours later it was around 6.7 to 6.5. 
Another 2 hours later it was 6.5, and at arund 6:30 it was again at 6.5. 
Looks like it is not dropping any more beyond 6.5. 
In summary, ph in my tank has a drop of approx. 1 from 10 am to 6pm.
I will take some readings before light out and in the morning again.
I am thinking of leaving CO2 on at night but add an airstone--my reasoning is that it will help to get rid of the excess Co2 and get enough o2 into the water for respiration. Is tha a good idea?
Will this swing cause too much stress to the fish and cause them to get sick easily?
PS, I have ADA Amazonia powder, Eco Complete, and Seachem Flourite in my tank.


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## effox (Apr 21, 2010)

I used to put an air stone in at night when I had DIY CO2. My only question is why do you have 3 different types of substrate in own tank?


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## Fish rookie (May 21, 2012)

I place the ADA int he front for the carpet. I got a bag of ECO real cheap and had a couple bags of Flourite from before so I decided to place them ont he back to make the substrate higher plus I heard they are pretty good for plants like amazon sword while the ADA is very good for carpeting plants like HC, glosso...ect. I had a bit of ADA left over so I cover the whole substrate with ADA. Another concern I had actually was that the power seemed very fine and I was worried they might beocme too compact if I apply them in the back of the tank to make it real deep. Not sure if it was a valid concern but that was what I thought that if there could have a bit of air in the substrate it would help the bacteria to grow especially when the substrate was so deep in the back.

Anyway, I suppose my main concern is if it is safe for the fish as I was told that even a 0.5 swing would put too much stress on the fish,.


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## effox (Apr 21, 2010)

With a KH of 7, and only a mild ph swing as a result, I'd believe they'd be okay. Mine were fine and I believe I was more so in the .7 range.


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## Fish rookie (May 21, 2012)

Thanks guys.


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## Scherb (Feb 10, 2011)

Hello. first off i know nothing about co2, but to me it seems crazy to have your ph swing a hole point everyday. that has to be hard on the fish. also, fishrookie what kind of plants do you have ? plants like amazon sword don't need co2, they do great with plant substrate and root tabs like seachem's. if you only have low light plants i would get rid of the co2. just my 2 cents. Cheers


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## Fish rookie (May 21, 2012)

I am not sure if it is hard on the fish which is why I asked. I would imagine a lot of planted tanks have a swing like this--although I am not sure of the magnitude. 
My fish seem to be fine, so I am actually not sure if it would really stress them out. I am concerned because I love my fish and I want the tank to be a good and comfortable home for them. For me it is not just about the plants looking good. Having said that, is there any scientific envidence that fish would be stressed out with a one point swing which happens gradually over the course of a day. I do have a high kH in my tank, does that help? 
I know some people say ph is very important but I have also heard some peopel say dont chase ph but just keep a steady kh and gh.
A lot of beautiful planted tank with Co2 have many fish and have been run for many years with no problem. This leads me to wonder if a Ph swing will do much harm to the fish then how did they do it?
Thanks a lot for all the advise.


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## Scherb (Feb 10, 2011)

Fish rookie said:


> I am not sure if it is hard on the fish which is why I asked. I would imagine a lot of planted tanks have a swing like this--although I am not sure of the magnitude.
> My fish seem to be fine, so I am actually not sure if it would really stress them out. I am concerned because I love my fish and I want the tank to be a good and comfortable home for them. For me it is not just about the plants looking good. Having said that, is there any scientific envidence that fish would be stressed out with a one point swing which happens gradually over the course of a day. I do have a high kH in my tank, does that help?
> I know some people say ph is very important but I have also heard some peopel say dont chase ph but just keep a steady kh and gh.
> A lot of beautiful planted tank with Co2 have many fish and have been run for many years with no problem. This leads me to wonder if a Ph swing will do much harm to the fish then how did they do it?
> Thanks a lot for all the advise.


Hello. the directions on a ph adjuster say not to adjust the ph more than 1 point in a day and that is what i have heard from many others. also a lot of co2 tanks have controllers to combat the ph swings. honestly i have not seen a diy co2 work good, pressurized is the best way, but big bucks for the good stuff. there are many attractive planted tanks without co2. hope that helps. Cheers


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## 2wheelsx2 (Apr 21, 2010)

Fish rookie said:


> I am not sure if it is hard on the fish which is why I asked. I would imagine a lot of planted tanks have a swing like this--although I am not sure of the magnitude.


It's not, otherwise everyone on plantedtank.net would have dead fish. pH is important, but more important is KH and GH. All these things have to be taken into account together. If you really want to get into this, here's one thread on Tom Barr's forum that discusses this. pH swings in the absence of CO2 injection is totally different than without. It's the same as the generalization that pH should be neutral. In blackwater environments, the pH is well below 6 from all the tannins, and many discus and blackwater fish keepers put wood and almond leaves to get it down there on purpose to induce breeding. I am by no means a CO2 expert, so please research for yourself on plantedtank.net and barrreport.com.

In all my years of using pressurized CO2 I have not killed any fish because of pH swings. CO2 toxicity (by accident) yes, pH no.

In the end it's up to you whether it's the plants that are important to you or the fish. As I think I have said earlier, I have both CO2 injected and natural tanks because some of plant important and some are fish important and I'm able to grow plants in both, but the CO2 injected tanks look like this:









While the non-pressurized tanks (but Metricide dosed) look like this. The plant mass difference is quite obvious. What's not obvious is the presence of algae.


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## 2wheelsx2 (Apr 21, 2010)

Scherb said:


> Hello. the directions on a ph adjuster say not to adjust the ph more than 1 point in a day and that is what i have heard from many others. also a lot of co2 tanks have controllers to combat the ph swings. honestly i have not seen a diy co2 work good, pressurized is the best way, but big bucks for the good stuff. there are many attractive planted tanks without co2. hope that helps. Cheers


A pH adjuster is using salts and other compounds to change the chemistry of the water for extended periods. CO2 pH swings are transitory.

And CO2 injectors use controllers not to control pH. Rather they use the control to control how much CO2 is injected via the pH measurement. DIY CO2 systems can work well in smaller tanks, but is a lot of work. And pressurized CO2 systems is not really "big bucks". A tank and controller is worth less than 2 Heckel discus. Is it big bucks? If your whole setup is worth $50, yes it is. But if you have $100 worth of Aquaflora plants, $200 worth of ADA AquaSoil as your substrate, and a $400 LED lighting system, then not really.


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## Fish rookie (May 21, 2012)

Scherb said:


> Hello. the directions on a ph adjuster say not to adjust the ph more than 1 point in a day and that is what i have heard from many others. also a lot of co2 tanks have controllers to combat the ph swings. honestly i have not seen a diy co2 work good, pressurized is the best way, but big bucks for the good stuff. there are many attractive planted tanks without co2. hope that helps. Cheers


How does a controller combat Ph swing? Is it true that it turns off the CO2 once the Ph has dropped to a certian level? If that is the case, it does nto really combat the swing but just stop it once it has swung to a certain point. In other words, there is a swing but to which magnitude is up to the person with the controller to control; the swing is not prevented nor "combated" but it allows the person the option to stop it from dropping. I can manully stop the CO2 as well if I want to--but that does nto mean the swing is prevented. I am concerned if the swing is common in planted tank, and if so, what is considered acceptable. Also, is the swing bad for the fish, and if so, how much is bad.
If you start with a 7.5 pH and you stop you Co2 at pH 7 you may not have enough Co2 in your tank. Of course it also depends on the KH which you have not really talked about. 
Ph would swing in a day due to many other factors from how I understand it. 
Making a DIY CO2 is fun and I also have a bubble counter built for my little system. I believe from looking at my PH and KH I have been able to dissolve enough or perhaps too much CO2 in my tank. My bubbles are very fine (like a fine mist) and they are circulated all over the tank. It is kind of fun to try to make it work.
I use Co2 because I believe Co2, Ferts, and Light are related and for plants to grow well they need to be balanced. I am just leanring to find a balance. I dont believe avoiding the problem is the best way to learn. I know I may mess up, which is why I come on here asking for help and advise but I do not want to change the plants in my tank so I do nto need to inject Co2 although I see whwere you are coming from and I agree it would be much less trouble.
Cheers.


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## Fish rookie (May 21, 2012)

2wheelsx2 said:


> It's not, otherwise everyone on plantedtank.net would have dead fish. pH is important, but more important is KH and GH. All these things have to be taken into account together. If you really want to get into this, here's one thread on Tom Barr's forum that discusses this. pH swings in the absence of CO2 injection is totally different than without. It's the same as the generalization that pH should be neutral. In blackwater environments, the pH is well below 6 from all the tannins, and many discus and blackwater fish keepers put wood and almond leaves to get it down there on purpose to induce breeding. I am by no means a CO2 expert, so please research for yourself on plantedtank.net and barrreport.com.
> 
> In all my years of using pressurized CO2 I have not killed any fish because of pH swings. CO2 toxicity (by accident) yes, pH no.
> 
> ...


Both of your tanks look very nice. Beautiful discus you have there.
Speaking of discus, when I was talking to a person in a LFS about Ph and I asked hom the Ph he kept his Discus in he told me they are kept in 7.5 with GH and Kh both around 4-5. He said it is because they were not caught in the wild and the hatchery bred them in that condition.
I have also read that a certain kH and Gh are better for plants so I naturally want to keep my water a bit soft and acidic.
Is it not the best for the fish I am nto sure. Can I have the best of both world? May be if I choose only fish who prefers slightly acidic water I have a chance to? But then if I buy a fish that was supposed to like acidic water which was kept in a 7.5 PH then I dont know LOL...
How does say Amano keep all the fish in good condition if a big swing is bad? His tanks must have some swing in pH on a daily basis, right?


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## 2wheelsx2 (Apr 21, 2010)

Thanks. Most of my discus are wild caught. You can see the details in my 100 gallon square tank journal. 

With regards to KH, GH, and pH, you should really have a read of Rastapus's thread on osmoregulation. It's not about the pH, but rather the KH and GH, which measures the amount of Ca, Mg and other compounds in the water with make the water "hard" or "soft". pH independent of GH and KH have almost no relevance.

Every tank that has plants has pH swings, CO2 or not, because CO2 is always present. As a matter of fact, if you measure pH at night after the lights are out, you'll see that pH is dropping as the plants are now respiring O2 and emitting CO2, because there is no photosynthesis.

This topic probably belongs more in the planted section, where you'll get more input on how it all work, than in freshwater chat. The objectives of a beautiful planted tank are somewhat different than a barebottom, high flsh load tank. For instance, Stingray keepers want close to 0 nitrate. If you had that in a CO2 injected, you'll get BGA, hence the reason for EI dosing.

You're not going to get all the answers in your one thread. I spent 6 months reading up on high tech planted tanks before I started one and then another 6 months before I went to a pressurized rig on one tank and then another year before I gave up on all DIY CO2. Do yourself a favour and look through all the planted section stickies here on algae and CO2, etc. and also visit plantedtank.net and barrreport.com. The experts there are much more qualified to answer all your questions than I am.


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## Fish rookie (May 21, 2012)

You are very qualified. Dont sell yourself short. 
But I will read all the info on the links you have provided, thank you so much once again.


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## effox (Apr 21, 2010)

Thanks for helping our newer member Gary, much appreciated, and great info and links!


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## Fish rookie (May 21, 2012)

I am not sure if it is true but after some thinking this is what i come up with: when people are talking about PH swing hurting fish I think they are referring to a change in mineral/eletrolye content in the water, which affects the osmoregulation of fish and hence could be harmful; while a PH swing with Co2 injection is different--eventhough it also results in a Ph swing--as it is about the introduction of carbonic acid as a result of Co2, which, as long as enough alkaline buffer is present, will not shift the hardness level, which is a measure of minrals needed for healthy osmoregulation. Because it will not remove the mineral needed for osmoregulation, it is not harmful to fish. This is also the reason why some people advocate not to chase ph but work on a steady harness.
What is your thought on this?


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## 2wheelsx2 (Apr 21, 2010)

True. Adding CO2 doesn't change the TDS and of course won't change the osmotic pressure in the tank. If anything, adding CO2 will cause dissolution of carbonates which would increase TDS, making it a better environment for the fish. CO2 injection combined with a bag of crushed coral in the filter will create a very stable pH and KH in the tank.


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