Using pH controller and KH dosing to control CO2 - The Planted Tank Forum
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 48 (permalink) Old 05-01-2015, 05:30 PM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: May 2015
Location: Kittery, ME
Posts: 103
Using pH controller and KH dosing to control CO2

Hello,

I have just purchased a pH controlled pressurized CO2 system for a new 75 gallon planted tank that I am setting up and I have a question that I cannot seem to find a definitive answer to. Optimally I would like to have a final tank pH of 7 and a CO2 level between 20-30ppm. Can I get to these levels by controlling the KH of the tank water, or should I avoid messing with the KH at all?

I have not tested my tap water myself (I will test as soon as the test kit comes in the mail), but the town water report states the following:
pH: 6.7
Total Hardness: 24ppm (1.35dGH?)

Obviously I want a CO2 level of about 20-30ppm for a high light tank, but I also want a final pH of 7 so that I have as many choices for fish as possible when I start deciding what I want to put in there (right now the tank has some guppies and a rainbow shark because they didn't have a home). Is the PH before I start injecting CO2 or after injecting CO2 what is important when choosing fish?

Some more info about my setup:
75 gallon tank 48x18x21
48" Finnex Ray2
PPS auto-dosing with peristaltic pump (yet to be setup)
jonsnow is offline  
Sponsored Links
Advertisement
 
post #2 of 48 (permalink) Old 05-01-2015, 05:35 PM
Planted Tank Enthusiast
 
natebuchholz's Avatar
 
PTrader: (12/100%)
Join Date: Sep 2013
Location: Sioux Falls, SD
Posts: 945
I wouldn't mess with your tap water more than you have to.

KH and PH can be a good indicators of the amount of CO2 dissolved in your water but, raising or lowering them does not necessarily change those concentrations.

The 1 degree fluctuation you should see with the CO2 concentration mentioned above would do little to affect any wildlife you would have in your tank.

Best,
Nate


Journals:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
natebuchholz is offline  
post #3 of 48 (permalink) Old 05-01-2015, 05:42 PM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: May 2015
Location: Kittery, ME
Posts: 103
I have read this sort of advice before, but I have not seen any decent explanations as to why this is the best direction to go. It seems like it would be fairly easy to dose my tank with calcium carbonate and baking soda to adjust the KH and GH during water changes, thus making it so I have optimal pH levels, CO2 levels, and enough buffers to make the water stable. Why isn't this a good route to take?

If I don't adjust the KH of my tap water I will be left with a final pH of about 6 when dosing CO2 to optimal levels, this seems very low to me. Is the initial pH of the water before CO2 injection all that matters to the fish and plants?
jonsnow is offline  
 
post #4 of 48 (permalink) Old 05-01-2015, 05:48 PM
Planted Tank Obsessed
 
imcmaster's Avatar
 
PTrader: (0/0%)
Join Date: Jan 2015
Location: Newmarket, Ontario, Canada
Posts: 385
I agree with Nate that you normally don't need to alter your tap water chemistry for the sake of the fish. There is no sense of 'optimum' for captive bred fish.

However, if you are very keen and enjoy this aspect of the hobby, I would target a particular kH (say 4-5) and try to keep it there. In this way, your pH controller will work as expected. If you allow your kH to drift low (and it will), then correspondingly the pH will shift lower, and your controller has to be re-tuned to keep the CO2 concentration where you want it to be.

I would say that the pH during light hours is a better indicator of your tank's pH. But it is commonly accepted that the pH swing caused by CO2 on/off has no consequence to your fish/plants.
imcmaster is offline  
post #5 of 48 (permalink) Old 05-01-2015, 06:10 PM
Wannabe Guru
 
hbosman's Avatar
 
PTrader: (2/100%)
Join Date: Oct 2006
Location: Leesburg Virginia
Posts: 1,728
Isn't GH more important than KH or PH for fish?
hbosman is offline  
post #6 of 48 (permalink) Old 05-01-2015, 06:14 PM
Planted Tanker
 
burr740's Avatar
 
PTrader: (126/100%)
Join Date: Feb 2014
Location: Bama
Posts: 5,776
PH drop from co2 has little to no effect on livestock. It's when you start messing with GH/KH that things get sticky.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




burr740 is online now  
post #7 of 48 (permalink) Old 05-01-2015, 07:34 PM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: May 2015
Location: Kittery, ME
Posts: 103
Burr740,

So you are saying that the pH before CO2 is added is the "actual" pH of the system that should be used to measure the safety of the fish? so if I have a fish that is suitable for a 6.8-7.5 environment and my pH before CO2 injection is 7, but after CO2 injection is 6 the fish will be fine? How can you explain this phenomenon?

To me an acidic environment is an acidic environment, no matter the chemicals that caused it, if a fish is not suited for an acidic environment how will it survive? There must be something that I do not understand about this scenario.
jonsnow is offline  
post #8 of 48 (permalink) Old 05-01-2015, 07:39 PM
Planted Tank Enthusiast
 
natebuchholz's Avatar
 
PTrader: (12/100%)
Join Date: Sep 2013
Location: Sioux Falls, SD
Posts: 945
A one degree shift is not an issue. Most of the fish we have in our tanks are captive bred and familiar to shifts in water parameters.

Let me ask you this. Do you think fish living in the wild have a constant PH in the water they live in? Do you think the amount of dissolved metals and gases ever change?

The big point is to create an environment that is stable and easily repeatable within a reasonable range of requirements for these species.

Best,
Nate


Journals:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
natebuchholz is offline  
post #9 of 48 (permalink) Old 05-01-2015, 07:40 PM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: May 2015
Location: Kittery, ME
Posts: 103
Quote:
Originally Posted by imcmaster View Post
I agree with Nate that you normally don't need to alter your tap water chemistry for the sake of the fish. There is no sense of 'optimum' for captive bred fish.

However, if you are very keen and enjoy this aspect of the hobby, I would target a particular kH (say 4-5) and try to keep it there. In this way, your pH controller will work as expected. If you allow your kH to drift low (and it will), then correspondingly the pH will shift lower, and your controller has to be re-tuned to keep the CO2 concentration where you want it to be.

I would say that the pH during light hours is a better indicator of your tank's pH. But it is commonly accepted that the pH swing caused by CO2 on/off has no consequence to your fish/plants.
I think that this is the direction that I want to take. I will shoot for a KH value that will keep my pH around 7 after injecting CO2. I will probably use a combination of calcium carbonate and baking soda determined by what I want my final GH levels to be as well. Is there anything wrong with this method? Will it be difficult to keep my KH levels stable/how often will I need to check these levels?

Bump:
Quote:
Originally Posted by natebuchholz View Post
A one degree shift is not an issue. Most of the fish we have in our tanks are captive bred and familiar to shifts in water parameters.

Let me ask you this. Do you think fish living in the wild have a constant PH in the water they live in? Do you think the amount of dissolved metals and gases ever change?

The big point is to create an environment that is stable and easily repeatable within a reasonable range of requirements for these species.
How can you make a general statement like this? A one degree pH shift may not effect one fish, but it may kill another. If I have a fish that thrives in a basic environment, it may be alright at close to neutral pH, but once that environment turns acidic (6) it may die.

Also, yes I believe that most of the environments these fish live natively are much more stable than a 75 gallon fish tank. The native environments are massive volumes of water compared to what we keep our fish in, if the parameters change they are doing so slowly and not by much.
jonsnow is offline  
post #10 of 48 (permalink) Old 05-01-2015, 07:44 PM
Planted Tank Obsessed
 
Malakian's Avatar
 
PTrader: (0/0%)
Join Date: Aug 2014
Location: Norway
Posts: 422
Also something to think about. If you are using a pH controller for Co2, you would want as stable KH as possible. In other words, don't fiddle with it. If the KH shifts even the slightest so will the Co2 ppm. And you would have to reset your controller for preferred drop/pH.

Edit: So when it rains and the river catches millions of liters of rainwater from nearby mountains/hills. You think the parameters stay the same? Highly unlikely. Also rain water is mainly PH 7 if not polluted. So if I use you logic, all freshwater bodies should be PH 7. No matter what. Since the water that is supplying the bodies with water is 7. Also what happens in the fall? Tree shed there leaves, falling off and rotting in the water. Leading to tanic acid, leading to a lowered pH, just because of season.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Malakian is offline  
post #11 of 48 (permalink) Old 05-01-2015, 07:49 PM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: May 2015
Location: Kittery, ME
Posts: 103
Quote:
Originally Posted by Malakian View Post
Also something to think about. If you are using a pH controller for Co2, you would want as stable KH as possible. In other words, don't fiddle with it. If the KH shifts even the slightest so will the Co2 ppm. And you would have to reset your controller for preferred drop/pH.

Edit: So when it rains and the river catches millions of liters of rainwater from nearby mountains/hills. You think the parameters stay the same? Highly unlikely.
Do you think that the pond comes anywhere close to a 50% water change like we do in our tanks? At most I would guess a 10% addition of water, even from heavy rain, but that is just a guess.

My question is still, how difficult is it to keep a stable KH? how fast does it change? Why are people advising against trying to fiddle with it?
jonsnow is offline  
post #12 of 48 (permalink) Old 05-01-2015, 07:55 PM
Planted Tank Obsessed
 
Malakian's Avatar
 
PTrader: (0/0%)
Join Date: Aug 2014
Location: Norway
Posts: 422
Quote:
Originally Posted by jonsnow View Post
My question is still, how difficult is it to keep a stable KH? how fast does it change? Why are people advising against trying to fiddle with it?
That has been answered. The inhabitants (no matter what you may think, this is from hundreds of people's experience) won't mind if you have a pH of 6 or 7. They are advising against it, because what you want is as stable system as possible, everything in the water is an equilibrium. So fiddling with it, is just another way to mess thing up. "If it's not broken, don't fix it".

Bump: Keeping a stable KH will depend on a lot of things. Substrate, acids added etc. It can change fast, It may not change at all. Only reason I see that you may want to bump up the KH, is for cycling purposes. Especially if you are going to use Ada aqua soil which will strip the water of KH the first weeks, leading to no/little bacteria growth. For the bacterias sake you want a KH of 3 or higher. Other than that, leave it alone. I'm talking from experience, with both fiddling with KH and pH controllers...It just ends up a big mess of variables if something goes wrong.

Also regarding the "ponds" 50% WC. First, most natural systems that resembles our planted tanks are rivers/streams, not bodies of still water. Second, when its heavy rain I'm pretty sure almost all (90%+) of the water is "new, water-changed" water flowing through the rivers. These little "squiggles" (rivers) on the map take up most of the rain water hitting the surrounding area. Keep that in mind, thats a butt load of water. Or not to mention when snow melts...


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Last edited by Malakian; 05-01-2015 at 08:08 PM. Reason: typo
Malakian is offline  
post #13 of 48 (permalink) Old 05-01-2015, 08:01 PM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: May 2015
Location: Kittery, ME
Posts: 103
Thank you, so how should I pick which fish will be suitable for my tank? Based off of the pre or post CO2 injection pH levels? Or are you literally saying it does not matter, and I should just ignore the pH recommendations for fish altogether?
jonsnow is offline  
post #14 of 48 (permalink) Old 05-01-2015, 08:13 PM
Planted Tank Obsessed
 
Malakian's Avatar
 
PTrader: (0/0%)
Join Date: Aug 2014
Location: Norway
Posts: 422
As long as you are in the 5.8-7.8 (probably even lower/higher then this)range, I would say, yeah ignore it all together unless you are breeding some very picky fish. Strive for stable KH/GH, instead of specific ranges. As long as you don't have any extremes (0 KH/GH or 20+ KH/GH). What you do want to keep an eye out for if you do decide to dose GH/KH, is to take it slow. Big/fast swings in these parameters will definitely impact fish/plants.

Bump: You might want to read up a bit more on the pH fluctuation and Co2. Correct me if I remember wrong, but I believe Tom Barr mentioned that lowering of the pH by Co2, is not the same as other acids/chemicals. This i'm just pulling out of my ass though, so research it yourself or take it with a grain of salt

2nd bump: You might want to check you local tap water supplier. I did, and my tap water contains 36ppm Ca, 0.3ppm Mg and 0.02ppm K as GH. So I need to add Mg and K for the plants at waterchange. I add 5-7ppm Mg and 18-20ppm K. Striving to take out as an exact amount of water each week as I can, and putting in the same amount of minerals each time. To try and keep things as stable as possible. I have a KH of 2.5 out of the tap, when I tried to fiddle with it it just lead to problems for me. Now I just leave it alone and things are tons better, not that all my problems are solved, but thats not related to this. And I use aqua soil, so by the end of the week its closer to 1.5-2 KH. Still no problem for C.Strebai, Cardinal tetras, otos, BNP, Black sakura, amano, platy, zebra danio, SAE's, clown loaches and yoyo loaches..and probably a bunch more I can't remember at the moment that I have kept under these conditions over the period of my aquarium career :P.

Ada Aqua soil and the drifting KH is the reason I'm not using a pH controller for regulating co2 anymore and dialing in the regulator the "correct" way instead. Eliminating further variables as drifting KH, phosphate buffers etc. When you adjust your regulator to say pump out 50ml pr min, it will do that no matter the KH/PH/GH whatever. With a controller, not so much. Still use it as a pH reader, and to dial in the regulator with a pH drop of 1.2-1.3. Tons easier, and more accurate then pH drop tests, so not a complete waste of money .hehe, sorry i'm a little harsh on the pH controller, but it's been the devils work for me.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Last edited by Malakian; 05-01-2015 at 08:58 PM. Reason: Added info
Malakian is offline  
post #15 of 48 (permalink) Old 05-01-2015, 08:42 PM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: May 2015
Location: Kittery, ME
Posts: 103
Thank you, I have read similar information that the pH fluctuations due to CO2 do not effect fish the same way normal pH swings would, but I have never come across any explanation of why that is the case.

Against your advice, I think I am going to experiment with my KH levels and check how stable they are if I supplement during water changes. My rationale is that KH is always going to be declining when supplementing CO2 and this rate should not be effected by what the actual KH value is (I'm assuming that the rate of change is linear given a constant CO2 level in the tank). So even if I'm not supplementing KH, the values will still go down by the same amount between water changes whether I am supplementing or not. As long as I am diligent about the volume of water changes and the weight of KH buffers being added I cannot predict an issue with this method. It really doesn't seem all that different than any other chemical that we mess with in the aquarium, so why is this the one thing that everyone says shouldn't be messed with?

I understand the less is more approach, but it seems like I'm going to have to be watching my KH levels anyway (since I'm controlling CO2 with a pH controller) so why not supplement? The testing is more of a pita than adding the chemicals.
jonsnow is offline  
Reply

Tags
kh co2, kh dosing, ph controller

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the The Planted Tank Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome