New to CO2, pH went from 7.4 to 6.6, can I raise it? - The Planted Tank Forum
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post #1 of 12 (permalink) Old 09-15-2020, 05:40 AM Thread Starter
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New to CO2, pH went from 7.4 to 6.6, can I raise it?

First timer doing CO2. I have a CO2Art setup ("SE" regulator + bazooka diffuser + drop checker) on a new ~70% planted 50 gallon. No critters yet, just plants (plants in approx order of area: dwarf hairgrass, rotalas, dwarf baby tears, swords, anubias).

I ran the CO2 for first time today. I knew pH would go down. I started at 7.4. At drop checker = green, I was at 6.6 (and I believe from the charts I was at ~30ppm CO2). I will be housing my many Endlers and adding both red cherry and amano shrimp. I know plants like a lower pH into the 6's but my Endlers I believe prefer 7-7.5 and have been living in that pH range. I'm thinking I would like to target 6.9 to get a happy middle ground. I have Seachem Alkaline Buffer on order.

My relevant tap water parameters are:
- 50-100ppm KH (based on API master kit), paper test shows ~80ppm
- 200-300ppm GH (based on prior readings with a Hanna probe and a truncheon, have an API test kit on the way)
- ~7.4pH (based on API master kit and paper test)

I also have a lot of Seiryu stone, which fizzled quite a bit when I prepped it in vinegar but it does not appear to affect my KH, at least as of yet. I wouldn't mind if it did and thought it might...

Anyway, based on a drop checker chart, it looks like to accomplish a move from 6.6 to 6.9 @ 30ppm CO2, I need to raise KH from 4 degrees of KH to 8 degrees of KH (or to about 144ppm). I'm sure the Seachem product will have a formula to calculate how much product to use.

I have a few questions:
1. Is it this straightforward to increase pH when using CO2 to just add some bufffer?
2. Does it raise my nominal pH also? So if CO2 is not on and I add fresh tap water prepped with the buffer, instead of 7.4 pH, should I get 7.8?
3. When I turn my CO2 off in the evening, does pH then go back up as CO2 is released and no more added to replace it (have not checked yet)? Doesn't this make using CO2 a pH yoyo? Does the buffer reduce the "swing" size any or does it just change the hi and low values of the pH swing by the same amount?
4. Will 8 degrees a KH (~144ppm) cause any issues I need to watch out for?

Appreciate any help!

Last edited by ahem; 09-15-2020 at 05:41 AM. Reason: added word "pH", confusing without it
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post #2 of 12 (permalink) Old 09-15-2020, 08:11 AM
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I wouldn’t do anything if I were you. Neocaridina will do just fine at a ph of 6.6. Many breeders use water from 6.5-7.5 with higher to a point being fine. My guppies did fine at this ph as well. Hardness is more of a concern for both so if you have a gh of 6-8 or higher all should be just fine. If you did want to adjust your kh up I would just target a specific kh in general and make sure it’s added to new water at water change. For example if using ro water for water changes you could use CACO3, CASO4 and MGSO4 with a target of 4 kh and 8 gh and all would be right in the world. If using tap I would use a liquid gh/kh test so you can see within 17.6ppm what those numbers actually are in addition to a tds meter. In my remineralized water I use the above mentioned compounds as well as 20 ppm potassium from KCL as well as a small amount of micro nutrients, iron etc.


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post #3 of 12 (permalink) Old 09-15-2020, 12:18 PM
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I wouldn't adjust anything. PH is a fairly good indicator of how much CO2 you're injecting. Many hobbyists here , including myself, have had no problems with a PH drop of 1-1.5 from our base PH due to CO2 injection. My PH drops from around 8.1 to 6.9~7.0 during peak CO2 injection. I have Endlers/Guppies, ramshorns and cherry shrimp in the tank and they're doing good.

And yes if you have your CO2 on a timer. Once it turns off, your PH should rise back to your base PH due to degassing of CO2 out of your tank.


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post #4 of 12 (permalink) Old 09-15-2020, 02:35 PM Thread Starter
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Originally Posted by Econde View Post
I wouldn't adjust anything. PH is a fairly good indicator of how much CO2 you're injecting. Many hobbyists here , including myself, have had no problems with a PH drop of 1-1.5 from our base PH due to CO2 injection. My PH drops from around 8.1 to 6.9~7.0 during peak CO2 injection. I have Endlers/Guppies, ramshorns and cherry shrimp in the tank and they're doing good.

And yes if you have your CO2 on a timer. Once it turns off, your PH should rise back to your base PH due to degassing of CO2 out of your tank.
Thanks for the answer. It's hard to see how that kind of daily pH swing is good for plants and animals but clearly lots of people are doing it with no ill effects and no funky algae forming so who am I to argue!

My other question is, does the buffer (if I use one I'll be using Seachem Alkaline) just change the 'begin' and 'end' pH by the SAME amount or does it decrease the "spread"?

For example:
I have 7.4 pH nominal water that goes to 6.6 pH @30ppm (after CO2 injection). If I add a quantity of buffer to change my 30ppm pH to 6.9 will that make my nominal water pH 7.7? (both high and low offset by +.3 pH?). So with buffered water, I would go from 7.7 pH nominal (no CO2) to 6.9 pH @30 ppm? (assuming I target an amount of buffer to get to 6.9 pH @ 30ppm).

Is the buffer's action completely linear? Apologies that I don't know how to ask this clearly. Just some places I read state that a buffer will HOLD a specific pH until the buffer is fully utilized, and only then does the pH start moving. So they seem to imply for example, if you add buffer to a 7 pH water source, it will then stay at 7 "more resiliently" until you add enough acid to counteract the buffer, and only then does pH start to fall. I'm trying to understand how a buffer behaves.
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post #5 of 12 (permalink) Old 09-15-2020, 02:50 PM
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Originally Posted by ahem View Post
Thanks for the answer. It's hard to see how that kind of daily pH swing is good for plants and animals but clearly lots of people are doing it with no ill effects and no funky algae forming so who am I to argue!

My other question is, does the buffer (if I use one I'll be using Seachem Alkaline) just change the 'begin' and 'end' pH by the SAME amount or does it decrease the "spread"?

For example:
I have 7.4 pH nominal water that goes to 6.6 pH @30ppm (after CO2 injection). If I add a quantity of buffer to change my 30ppm pH to 6.9 will that make my nominal water pH 7.7? (both high and low offset by +.3 pH?). So with buffered water, I would go from 7.7 pH nominal (no CO2) to 6.9 pH @30 ppm? (assuming I target an amount of buffer to get to 6.9 pH @ 30ppm).

Is the buffer's action completely linear? Apologies that I don't know how to ask this clearly. Just some places I read state that a buffer will HOLD a specific pH until the buffer is fully utilized, and only then does the pH start moving. So they seem to imply for example, if you add buffer to a 7 pH water source, it will then stay at 7 "more resiliently" until you add enough acid to counteract the buffer, and only then does pH start to fall. I'm trying to understand how a buffer behaves.
If you're going to change your PH level, I'd change the base and not chase the drop. The 2HR aquarist spread sheet on what PH level drops are needed vs PH/KH levels. You can find it HERE.

Tbh with you, I myself have stopped chasing KH and PH levels. I run tap water on my 2 tanks currently. I used to remineralize RO water and eventually gave up. Also Sodium bicarbonate (baking soda) will raise KH/PH on the cheap.
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post #6 of 12 (permalink) Old 09-15-2020, 03:04 PM Thread Starter
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Originally Posted by Econde View Post
If you're going to change your PH level, I'd change the base and not chase the drop. The 2HR aquarist spread sheet on what PH level drops are needed vs PH/KH levels. You can find it HERE.

Tbh with you, I myself have stopped chasing KH and PH levels. I run tap water on my 2 tanks currently. I used to remineralize RO water and eventually gave up. Also Sodium bicarbonate (baking soda) will raise KH/PH on the cheap.
Yes, I'm doing tap water also. I'm using the commonly available red/yellow/green "drop counter chart" to determine my target. I'm not talking about adding buffer AFTER I inject CO2 to "chase the drop". I am looking to "nudge" the pH up a little. My tap water KH is 4, I am thinking a KH of 8 would result in a better pH range for my endlers. But trying to understand what to expect with a buffer. Would it change my starting pH (no CO2) and ending pH (@30ppm) by exactly the same amount?

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Originally Posted by Econde View Post
If you're going to change your PH level, I'd change the base and not chase the drop. The 2HR aquarist spread sheet on what PH level drops are needed vs PH/KH levels. You can find it HERE.
This is a great little informative piece, thank you!!!
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post #7 of 12 (permalink) Old 09-15-2020, 03:15 PM
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Quote:
Originally Posted by ahem View Post
Yes, I'm doing tap water also. I'm using the commonly available red/yellow/green "drop counter chart" to determine my target. I'm not talking about adding buffer AFTER I inject CO2 to "chase the drop". I am looking to "nudge" the pH up a little. My tap water KH is 4, I am thinking a KH of 8 would result in a better pH range for my endlers. But trying to understand what to expect with a buffer. Would it change my starting pH (no CO2) and ending pH (@30ppm) by exactly the same amount?

Bump:

This is a great little informative piece, thank you!!!
To my understanding, it should change your starting PH which should change your ending PH as well. Read through the link at the bottom. There's a lot of science there that I can't explain .

https://www.plantedtank.net/forums/1...lp-needed.html


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post #8 of 12 (permalink) Old 09-15-2020, 03:35 PM Thread Starter
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To my understanding, it should change your starting PH which should change your ending PH as well. Read through the link at the bottom. There's a lot of science there that I can't explain .

https://www.plantedtank.net/forums/1...lp-needed.html
Thank you, looks like a great read, although right off the bat someone is saying to not use a drop checker which nobody else online says to do

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Originally Posted by Econde View Post
To my understanding, it should change your starting PH which should change your ending PH as well. Read through the link at the bottom. There's a lot of science there that I can't explain .

https://www.plantedtank.net/forums/1...lp-needed.html
While I can't tell the poster's qualifications they did give the answer I was looking for:

"Myth: A Low KH results in a larger pH swing when adding CO2.
Many people are under the mistaken impression that a low KH results in large pH swings when adding CO2, while raising the KH will result in smaller pH swings. This is not the case. The KH will move the start and end pH values, but the pH swing will be the same for a given level of CO2. You can see this in the chart below, or using the calculation:"
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post #9 of 12 (permalink) Old 09-15-2020, 03:42 PM
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Thank you, looks like a great read, although right off the bat someone is saying to not use a drop checker which nobody else online says to do
Hehe. Drop checker is not the best indicator. I do have one in my tank though for a quick glance. PH drop and KH levels supposedly have the best indication to CO2 levels. Anyway it's a lot of science I'm not too sure of . Hoping this has helped you in some way.


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post #10 of 12 (permalink) Old 09-15-2020, 04:12 PM Thread Starter
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Hehe. Drop checker is not the best indicator. I do have one in my tank though for a quick glance. PH drop and KH levels supposedly have the best indication to CO2 levels. Anyway it's a lot of science I'm not too sure of . Hoping this has helped you in some way.
Yes the drop checker seems very useful and at the very least safety net to alert to a potentially harmful situation.

I am almost certain I have phosphates in my water (have a test kit on the way), according to that post link you sent, that might screw my calcs a little.

Thanks for all your help! Got me on my way.
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post #11 of 12 (permalink) Old 09-15-2020, 09:47 PM
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I also have a lot of Seiryu stone, which fizzled quite a bit when I prepped it in vinegar but it does not appear to affect my KH, at least as of yet. I wouldn't mind if it did and thought it might...
Besides from the good information you received already, if you have alot of Seiryu stone it will definitely raise your KH anyway, sometimes substantially. My KH goes from 4 (tap) to 8-12, depending on water changes. I've had endlers in tanks with kh 4 and now with the 8-12 and noticed no difference. One of my endlers is going to be 4 in November. I also have a ton of RCS and some amanos and there is no problem with large KH swings after water changes.
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post #12 of 12 (permalink) Old 09-15-2020, 10:58 PM Thread Starter
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Besides from the good information you received already, if you have alot of Seiryu stone it will definitely raise your KH anyway, sometimes substantially. My KH goes from 4 (tap) to 8-12, depending on water changes. I've had endlers in tanks with kh 4 and now with the 8-12 and noticed no difference. One of my endlers is going to be 4 in November. I also have a ton of RCS and some amanos and there is no problem with large KH swings after water changes.
Very good to know endlers and RCS should be fine based on the water parms.

I was hoping the stones would raise my KH some. They sure fizzed a lot when I vinegar washed them (vinegar made them look spectacular). But so far after 4 days submerged, they have not changed my KH beyond my tap water but going to test everyday, maybe it is a gradual change.

The API KH test kit doesn't have very high resolution, I go to 4 drops, which is "50-100ppm" which is KH 3-5.

I like the API tests but maybe there a more precise test or method for KH, need to research that on these threads and maybe start a new thread.
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