CO2 levels too high... - The Planted Tank Forum
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 24 (permalink) Old 08-14-2015, 03:30 AM Thread Starter
Planted Tank Guru
 
klibs's Avatar
 
PTrader: (29/100%)
Join Date: May 2014
Location: NH
Posts: 3,325
CO2 levels too high...

I think I am injecting a little too much CO2 into my tank. A few of my fish (they are all rummynose tetras) tend to hide in the corner during the photoperiod. All others are totally fine. They only hide during the photoperiod so I am quite convinced it is because of too much CO2.

I run a pH controller (Apex) to set my CO2 so I could be pretty precise as to what pH I want to set the CO2 at. Right now it drops about 1.3 pH down from ~8.0 (after letting tank water sit for a day) to 6.7

2 questions:

Are there diminishing returns with how much CO2 you inject? My point is that I want to turn down CO2 to the point where my fish are not harmed at all but am wondering if my plants will not be able to take in as much light / I may run into algae issues if I do this. If I will be 'safe' by lowering my CO2 down to the max level that is safe for fish I am hoping that the plants will be able to grow at the same rate / not be deficient vs the amount I have previously been injecting.

Should I just slowly raise the level my CO2 turns off at by like 0.02 at a time and wait until the fish look all good? Frankly I am terrified of getting an algae bloom so some assurance / facts around if plants 'max out' their CO2 consumption at a certain level would be good.


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.
klibs is offline  
Sponsored Links
Advertisement
 
post #2 of 24 (permalink) Old 08-14-2015, 04:55 AM
Planted Tank Enthusiast
 
PTrader: (0/0%)
Join Date: May 2015
Location: the desert
Posts: 541
Yeah, I have been worried about the same thing lately. My PH in de-gassed water is 8.3 and with co2 it is 7.0. Since I am using DIY co2 I can't really turn it down. What I have done is adjust one of my filter outlets to get a bit of surface movement and at least it should be getting more o2. It has not done much to lower the co2 level but the fish are not acting weird anymore.

In my case I recently moved some Bosemani rainbows out of that tank due to them growing too big and since then my SAE has become a real bully. I think he is the reason that my Flame tetras have been hiding since he chases them around. And the other day I was freaked out because he was real pale and just laying around. Happened again yesterday and when I did a little pruning he perked right up and displayed his colors so I think that most of what I was observing was just power struggle and the fish are just re-establishing their territory. I think I should be safe from the gassing point by a fair margin. I estimate around 30 PPM and I think the danger point is closer to 40.
keymastr is offline  
post #3 of 24 (permalink) Old 08-14-2015, 12:57 PM Thread Starter
Planted Tank Guru
 
klibs's Avatar
 
PTrader: (29/100%)
Join Date: May 2014
Location: NH
Posts: 3,325
It would not surprise me if I had 40ppm in my tank. I luckily run my CO2 levels off of a pH controller so I can fine tune it pretty well.

Hopefully someone can chime in... I really just need confidence that my tank at 40ppm will be just as stable as my tank with 20-30ppm CO2


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.
klibs is offline  
 
post #4 of 24 (permalink) Old 08-14-2015, 01:13 PM
Wannabe Guru
 
bsantucci's Avatar
 
PTrader: (22/100%)
Join Date: Sep 2013
Location: New Jersey
Posts: 1,598
I recently noted the same thing wiht my fish. Tank would go from 7.3 down to 5.95 each day. They were doing great when I ran my sump but I switched away to canister again and should have fixed my co2 to match.

I saw bad coloring on my rams and lethargy from them. Bumped the bottom pH to 6.15 and everything is great again. I had no issues with algae or anything else. I also run an apex in the same way you do.

If you want to play it safe, lower your light levels when you make the change, then slowly raise them again.
bsantucci is offline  
post #5 of 24 (permalink) Old 08-14-2015, 01:16 PM Thread Starter
Planted Tank Guru
 
klibs's Avatar
 
PTrader: (29/100%)
Join Date: May 2014
Location: NH
Posts: 3,325
That's what I wanted to hear. Thank you! I will slowly bump up my CO2 by like 0.02 per day until I no longer see signs of stress. It's not like I'm losing livestock - they are just unhappy. Same thing as you - poor coloration and lethargic.

The funny thing for me is that 90% of my rummys are totally fine and only like 2 or 3 are really hurting from this.


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.
klibs is offline  
post #6 of 24 (permalink) Old 08-14-2015, 02:11 PM
Planted Tank Enthusiast
 
chinaboy1021's Avatar
 
PTrader: (0/0%)
Join Date: May 2003
Location: toronto
Posts: 542
I'm having this issue also. I only have several serpae tetras in a 75 gallon (very heavily planted - jungle style) and the tetras are not active. They are also sometimes swimming at an angle. These fish had previously been super active and always hungry.

That said - we need to tone co2 down without hurting the healthy plant growth. I think we need to keep an eye out on our lighting. Might need to lower the light to match decreasing co2 levels.
chinaboy1021 is offline  
post #7 of 24 (permalink) Old 08-14-2015, 02:27 PM
Wannabe Guru
 
bsantucci's Avatar
 
PTrader: (22/100%)
Join Date: Sep 2013
Location: New Jersey
Posts: 1,598
Quote:
Originally Posted by klibs View Post
That's what I wanted to hear. Thank you! I will slowly bump up my CO2 by like 0.02 per day until I no longer see signs of stress. It's not like I'm losing livestock - they are just unhappy. Same thing as you - poor coloration and lethargic.

The funny thing for me is that 90% of my rummys are totally fine and only like 2 or 3 are really hurting from this.
Yep, the rest of my fish in my tank were fine too, otos, corys, apistos, etc. You're playing it safer than I did. I just bumped it all at once. Also changed from BML regular lights to MC lights at the same time, so had to alter my lighting levels on the fly. All in all, worked out fine. In fact, I bumped my phosphate dosing up at the same time and in the end I got rid of all GSA on top of having happier fish and healthy plants.
bsantucci is offline  
post #8 of 24 (permalink) Old 08-14-2015, 03:01 PM Thread Starter
Planted Tank Guru
 
klibs's Avatar
 
PTrader: (29/100%)
Join Date: May 2014
Location: NH
Posts: 3,325
lol I tend to do the same thing. Make a bunch of changes at once based on what I believe is the best route to go. Can definitely end badly if you aren't 100% correct!

I'll try to play this one safe and see how it goes. Thanks again


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.
klibs is offline  
post #9 of 24 (permalink) Old 08-15-2015, 03:35 AM
Banned
 
PTrader: (0/0%)
Join Date: Apr 2015
Location: Queensland
Posts: 525
CO2 contribution to plant growth is a logarithmic scale. If you reduce CO2 concentration from 40ppm to 30ppm, you don't scale back growth by 25%, more like 2%.

http://www.bio-web.dk/ole_pedersen/p..._2001_2_22.pdf

There's also a good post at the barr report somewhere regarding CO2 saturation.

In terms of algae, consistency is the key, not the actual level of CO2.

Feel free to edit.
Audionut is offline  
post #10 of 24 (permalink) Old 08-15-2015, 05:55 PM Thread Starter
Planted Tank Guru
 
klibs's Avatar
 
PTrader: (29/100%)
Join Date: May 2014
Location: NH
Posts: 3,325
Quote:
Originally Posted by Audionut View Post
CO2 contribution to plant growth is a logarithmic scale. If you reduce CO2 concentration from 40ppm to 30ppm, you don't scale back growth by 25%, more like 2%.

http://www.bio-web.dk/ole_pedersen/p..._2001_2_22.pdf

There's also a good post at the barr report somewhere regarding CO2 saturation.

In terms of algae, consistency is the key, not the actual level of CO2.
Perfect - this is what I assumed was the case. Thank you for the info!


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.
klibs is offline  
post #11 of 24 (permalink) Old 08-15-2015, 06:32 PM
Algae Grower
 
PTrader: (0/0%)
Join Date: Jun 2011
Location: Phoenix, Arizona
Posts: 43
Another issue you may consider is better oxygen exchange via increased surface agitation.

I have a similar setup as you (Apex controller). I was pushing almost a 1 point decrease in ph. The existing fish were doing fine. Added some rummynoses and cardinals. The weaker ones couldn't handle it and perished. I was bummed. Since then I cut the ph decrease in half and increased the surface agitation. The plants are still exploding in growth and there is minuscule amounts of algae. I'm convinced I still need more agitation before I increase the co2.
prp427 is offline  
post #12 of 24 (permalink) Old 08-15-2015, 09:06 PM
Children Boogie
 
mistergreen's Avatar
 
PTrader: (13/100%)
Join Date: Dec 2006
Location: Cincinnati
Posts: 16,743
Light intensity drives plant growth. Lower the CO2, lower the PAR or PUR and you should be fine with no algae issue.
mistergreen is offline  
post #13 of 24 (permalink) Old 08-16-2015, 02:22 AM
Banned
 
PTrader: (0/0%)
Join Date: Apr 2015
Location: Queensland
Posts: 525
Quote:
Originally Posted by prp427 View Post
Another issue you may consider is better oxygen exchange via increased surface agitation.
If you think you have enough agitation, you don't.
Far better to skim the DOC's from the surface, but that's another story.

Quote:
Originally Posted by mistergreen View Post
Light intensity drives plant growth. Lower the CO2, lower the PAR or PUR and you should be fine with no algae issue.
Light is also on a logarithmic scale, however plants can utilize significant amounts of light well in excess of the levels we can control in an aquarium. Since we are already far away from the light saturation point, reduction in light can cause a significant reduction in growth.

Where CO2 concentration is near saturation for growth, reducing CO2 concentration will only reduce growth by a small margin. Look at some graphs in the PDF I linked. As CO2 is increased above equilibrium with the atmosphere growth rate is increased exponentially. However, as CO2 concentration reaches saturation (actually quite a bit before saturation), growth levels tapper off.

Increase CO2 concentration from 3ppm to 20ppm and the growth rate will increase significantly. Increase CO2 concentration from 20ppm to 40ppm, and the growth rate only increases slightly. This allows some margin of error. So for those of us who like to push things to the limit, we can actually reduce CO2 concentration somewhat, suffer little reduction in growth rates of the aquarium, and make life more comfortable for other inhabitants.

Reducing both CO2 and light will reduce growth significantly, which is probably not the outcome those with excess CO2 supply desire.

Algae adapt to changes in CO2 concentration far quicker then plants are able to adapt. We don't set CO2 concentration to control algae, we set CO2 concentration for optimum plant growth, since it's healthy plant growth that reduces the ability of algae to thrive. Once we have our desired CO2 level, it's all about maintaining consistency. It's also important to remember that CO2 concentration has a direct relationship with carbonate levels, so to maintain consistent CO2 levels in the aquarium, pH alone is not a sufficient indicator (actually it's an ok indicator, but requires careful monitoring which rules out pH controlled CO2 injection), one must also monitor carbonate concentration. If you have some substrate that reduces carbonate concentration, then it is also reducing CO2 concentration for the same pH.

In this case, with a water change the aquarium has some specific carbonate level, over time the carbonate level is reduced, which also reduces CO2 concentration for the same pH. Next week with another water change, carbonate levels are increased, which also increases CO2 concentration for the same pH.

Bouncing CO2 concentrations for the same pH, which provides conditions more suitable for algae then plants. In this specific example, a carbonate source added to the aquarium (small amount of shell grit, or whatever), will offset carbonate loss and help to maintain consistent CO2 concentrations even during water changes.

Feel free to edit.

Last edited by Audionut; 08-16-2015 at 02:28 AM. Reason: added note to pH indicator
Audionut is offline  
post #14 of 24 (permalink) Old 08-16-2015, 03:04 AM
Children Boogie
 
mistergreen's Avatar
 
PTrader: (13/100%)
Join Date: Dec 2006
Location: Cincinnati
Posts: 16,743
Light drive algae too.

Going from 40 to 30 ppm without reducing light is asking for Blackbeard algae from personal experience. Those that have or had it knows 😃


Sent from my iPad using Tapatalk HD


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
mistergreen is offline  
post #15 of 24 (permalink) Old 08-16-2015, 04:16 AM
Planted Tank Enthusiast
 
PTrader: (2/100%)
Join Date: Oct 2012
Location: California
Posts: 897
The best way is to observe plant growth and see if you get the same results reducing the C02. If you want the best of both worlds then run an airstone and increase the C02 injection to match the current PH drop. That way you have high 02 levels with good amount of c02.

I do this with my tank but I use an HOB that creates agitation.


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

Tags
None

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