Refugiums, dissolve oxygen and Co2

Rogger Castells

New member
I haven't wrote in a while but I am always reading our forum and I see we have a lot of new members which I am happy to see, I would like to start a conversation about something that a lot of us don't really check in our tanks but IMO is very important for a healthy tank.
These are Oxygen & CO2 content in the water.
Oxygen and CO2 are a gasses when is in the air but they dissolve in the water, dissolved Oxygen is imperative to fish and dissolved CO2 is important to marine plants as they need it to photosynthesis and thus produce oxygen.
There are kids that can measure dissolve O2 which are very common, there are also a few companies making probes that are control by your current computers.
Co2 testing is almost unheard of in the hobby but I found that there is a direct correlation between the dissolved CO2 content in the water and the health of the tank in general, there are several companies that sell CO2 test kits like LaMotte and Hach there are also several independent electronic test devices for a faster testing.
Co2 acts like a fertilizer in tanks as it use for photosynthesis, it usually accumulates higher than need and since most of us don't check it we don't know what to correct. Most living organism in our tank produce CO2 on top of that Calcium reactors use CO2 to dissolve the lime media and that adds to the CO2 accumulation, and if that wasn't enough, in a normal house here in south fl which keeps the windows down and ac on all day, co2 increases and your air pumps and protein skimmer injected in the water and Bamm! you got excess co2!
Refugiums in a tank if set up correctly help keep the balance of this dissolved gasses in check, they utilized the dissolved CO2 in photosynthesis and produce oxygen which is then utilized by the fish and corals.
I Plan to by a Co2 meter as soon as I set my tank back up, I have been monitoring both by ways of test kits for years and find it essential for the well being of the animals we care for, I hope that this help you guys, Cheers!
 
Good info Rogger, thanks.

Ide like to add to your statement about CO2 accumulation in our homes here in South Florida. The fact that this happens is one of the reasons we sometimes struggle keeping PH at what we prefer for our tanks. PH is directly affected by increased CO2 since PH is a correlation of Hydrogen, one of the components of CO2. So the higher the CO2 in the home, the lower the PH goes. Some choose to place CO2 absorbers in their PS intake lines, others choose to open the windows as much as possible.

Regarding O2, one of the best ways that i know of to increase in our tanks is to keep the surface agitated, hence why many point powerheads to the surface.

Thanks again Rogger.
 
Yes, excess co2 will lead to lower ph readings, lower ph will also do something most people don't want, it will slow down coral growth.
One thing I didn't mention is that the temperature of your water will have a lot to do with the dissolve oxygen saturation level, colder water can hold more oxygen and more dissolved oxygen is also beneficial in the health of all living things.
 
I haven't wrote in a while but I am always reading our forum and I see we have a lot of new members which I am happy to see, I would like to start a conversation about something

There are kids that can measure dissolve O2 which are very common,

Very nice write up Roger thanks ......and by the way where can I get one of these kids, they must not be that common mine won't measure anything for me
 
Thank you Matt, salifert makes a good oxygen test kit, the co2 is sold by hydroponics stores, there are many online stores that sells it. Hach and laMotte makes the more expensive test kits but worth the money, however there are other brands that make inexpensive test kits too.
This same company have electronic instruments to test for both.
 
Thank you Matt, salifert makes a good oxygen test kit, the co2 is sold by hydroponics stores, there are many online stores that sells it. Hach and laMotte makes the more expensive test kits but worth the money, however there are other brands that make inexpensive test kits too.
This same company have electronic instruments to test for both.

Oye- Matt is making a joke. You said "kids" are common to measure O2.
 
Lmao, didn't noticed the typo, I guess the answer should be bring your water here, I have my kids checking my water, in fact I have make it some how a privilege to be able to test the water lol
 
Thanks for the post Rogger; you've always given me great advice.

I am one of those people that Eddie mentioned who run a CO2 scrubber. I keep my windows closed and A/C on most of the year. I've noticed a big difference in pH when I added it. I've never tested for CO2; I'll look into a test kit. Maybe it will give me more of a quantitative analysis of using my CO2 scrubber vs just a rise in pH.

As far as O2 test kits, I've purchased the salifert and red sea. I cant say I would recommend either of them. The results seem to be inconsistent for me. If I was more serious about tracking dissolved oxygen, I would purchase a probe. I've seen them on Amazon for about $150 (Milwaukee MW600)

My take on CO2 and Dissolved oxygen: Unless there is a specific reason you need to monitor it, it is a luxury item and not really needed by most reefers.

I look forward to reading about your epic new build Rogger!
 
Thanks for the post Rogger; you've always given me great advice.

I am one of those people that Eddie mentioned who run a CO2 scrubber. I keep my windows closed and A/C on most of the year. I've noticed a big difference in pH when I added it. I've never tested for CO2; I'll look into a test kit. Maybe it will give me more of a quantitative analysis of using my CO2 scrubber vs just a rise in pH.

As far as O2 test kits, I've purchased the salifert and red sea. I cant say I would recommend either of them. The results seem to be inconsistent for me. If I was more serious about tracking dissolved oxygen, I would purchase a probe. I've seen them on Amazon for about $150 (Milwaukee MW600)

My take on CO2 and Dissolved oxygen: Unless there is a specific reason you need to monitor it, it is a luxury item and not really needed by most reefers.

I look forward to reading about your epic new build Rogger!


I agree Dr. Its a luxury to measure these items, but the knowledge needs to be know by reefers that these are indeed things we need to understand.

That being said, IMHO Ph is a good determining measurement of CO2, why measure CO2 in and of itself. The only place we will see a difference is in PH?. Im not one to chase Ph very much since really there is little we can do other then run CO2 scrubbers in our PS intake, and open up windows. Both things for me are very undesirable. So I do my best with dosing Kalk for all my evaporated water, and wish for the best.

:wavehand:
 
Lmao, didn't noticed the typo, I guess the answer should be bring your water here, I have my kids checking my water, in fact I have make it some how a privilege to be able to test the water lol

Lol love it Roger I'm going to take you up on that next time I'm over and for sure going to use your psychology on my own kids and maybe get them to do more than phone their mother and ask for another grape soda.....
 
Thank you Dave, it may seem like a luxury to you but I think that contrary to many other people that I have seen starting on this hobby, you seem to educate your self well before starting anything new, I have a feeling that even though you may have not noticed it, this have made things appear easier to you than they are.
I remember the emphasis you put when you first started your denitrator, you asked a thousand questions, but I also remember that you were one of the few people that I have seen being successful relatively quick at mastering and understanding the process, and I bet you think it was easy!
The monitoring of dissolved O2 & Co2 are a luxury only if you don't mind unexplained crashes which I doubt you have experienced yet, what I mean with unexplained are those crashes in your tank that happened when everything else seem fine.
Every crash I have experience have had correlation with low oxygen levels, even fish and coral health can be increased by keeping oxygen at saturation levels, unfortunately there is no visual sign of saturation level, so you have to test.
 
Just a thought.. Would keeping a few live plants in your home help keep co2 in check even if you keep your windows and doors closed while using ac? If so, id recommend buying a few plants for your wife!
 
I found this article online
http://phys.org/news/2013-07-air-hidden-indoor.html

this is a part that was interesting

"More recent experimentation has monitored the background concentrations of volatile organic compounds in offices with and without plants over some weeks. These findings indicate that even three potted plants in an average-sized office will reduce airborne volatile organic compounds to an extremely low level.
Plant-mediated CO2 removal has received less research attention, primarily because this pollutant is well controlled by modern air conditioning systems. But field trials have shown that between three and six medium-sized plants in a non-air conditioned building can reduce CO2 concentrations by a quarter."
 
Yeah, i figured plants take up co2 and expel oxygen. That article Kinda sounds like you need plants to create a human refugium!
 
In my opinion, is not that easy, pH does not tell you CO2. There are many other processes in the aquarium which can acidify the water other than carbonic acid.

Also, CO2 is necessary during photosynthesis so it's needed for coral growth. Calcium reactor during the day adds calcium, carbonate and, just as important for growth, CO2.

I think a crash can happen a lot more sudden from a lack of dissolved O2 than an excess amount of Co2. A sudden lack of Oxygen is far more detrimental than a chronic case of elevated CO2 levels. Alkalinity helps you buffer the amount the carbonic acid can drop your pH. This is analogous, in my view, to human blood as it relates to oxygenation and metabolism.

Good discussion.
 
You quite correct that pH in and of itself tells you nothing about CO2 in the water. Though there is a nifty little trick that does let you use pH measurements to determine if CO2 elevated from normal atmospheric (i.e. outdoors in the fresh air) levels. Simply take a sample of aquarium water and measure the pH. Then take that sample outside in the fresh air and heavily aerate. Check the pH after that, and if it went up, your tank pH is being effected by elevated CO2 levels.
 
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