# How do I measure CO2 in tank



## Red (Aug 20, 2009)

What is the best way to measure the CO2 in my aquarium?

I have a 29 gal tank and currently use a 'Red Sea CO2 Bio Generator' however I am using DYI formula as my mix. At this point I would like to go as cheap as possible but still get an accurate reading. At present I have 1 amazon sword, 2 crypts and 3 other small bush type plant.

CO2 area seems quite foreign to me at the moment and am just trying to take 1 step at a time.

Thanks


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## gucci17 (Oct 11, 2007)

Here's something I just googled and will give you a good idea on _drop checkers_

It is really hard to get an accurate reading of co2 in your tank per say. There are ways to measure but in your case of DIY co2, I wouldn't worry too much about it. Essentially, that kit is the same as DIY co2 and I would think it is just about right for the size of your tank.

Is there a particular reason you would like to measure the co2 levels in your tank?


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## Chris S (Dec 19, 2007)

No need to measure in your tank (and setup) really, just try and have your system pumping out the max amount of co2 as possible.


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## Red (Aug 20, 2009)

I think I have BGA - don't have pics with me but it's the right colour, seems to have jelly-like texture and comes back as quick as I remove it. 

Anyway, I think I originally was overfeeding my fish (8 red-eyed tetras, 4 harlequin rasboras, 1 BN pleco), I do at least a weekly water change to 20%+ and water parameters have been consistently ammonia 0; nitrites 0; nitrates about 10-20 using the liquid test kits. 

Every article I've read indicates BGA is nasty to get rid of but some seem to indicate that having proper CO2 levels (whatever that means) is important in keeping BGA from coming back once/if you get rid of it.


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## gucci17 (Oct 11, 2007)

Although I've never encountered a full blown BGA outbreak, I've used the blackout method which got rid of it. Not sure how it worked but BGA never really seemed to bother me when I had planted tanks.

I've heard of Nitrogen deficiences or what not as the cause. Not sure if that's a fact or just speculation. If you have access to some ferts, perhaps you can try dosing some KNO3 to suppliment Nitrogen.

Then there's antibiotics (erythromycin) that is supposed to work. I've never tried so again I can't comment on it's effectiveness.


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## Consigliere (Jun 11, 2009)

Overfeeding will typically not cause algae issues if you are measuring 0 ammonia. The problem with overfeeding is that it puts ammonia in the tank and algae requires only ammonia and light to thrive.

Potentially you could have high phosphates with overfeeding but that also is usually not a cause of BGA, if that is what you have.

For 29G tank, DIY CO2 might be a bit touch and go. You will definitely have to keep up on it to keep high enough levels. With the level of planting you have though, I wouldn't expect that low CO2 is really the issue considering you have slow growers that don't require CO2 supplementation. The real key with algae is balance of CO2, nutrients and light.

What are is your lighting for this tank? Are you fertilizing the tank in any way? What are the "bush type plants"? These are all questions that need answering to address the algae situation.

My expectation with the limited information is you have either excess CO2 in the tank. I would take the CO2 offline, clean the BGA up, do at least 25% water change and black the tank out for 3 days. After that, start up with a shorter photoperiod and see how things go. It would also help to do a vacuum and clean out the filter during the blackout.


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## Red (Aug 20, 2009)

Consigliere said:


> What are is your lighting for this tank? Are you fertilizing the tank in any way? What are the "bush type plants"? These are all questions that need answering to address the algae situation.
> 
> I have a Coralife T5 double bulb 30" - 1 bulb full spectrum & the other is 6700K which I have on a timer for 10 hours per day. The bush type plant is actually a 'cardinal plant' Lobelia cardinalis (true aquatic according the the plastic strip that came with the plant). I use root tabs at the base of the amazon and something called 'lilygro'. The person at the LFS recommended this instead of root tabs.


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## Zebrapl3co (Mar 29, 2006)

That doesn't look like black beard algae. Looks like a green slime algae. Can't remember the name right now.
Let me see if I can find that fantastic DIY CO2 indicator a member of this forum posted a while back. ....
Aha! here it is, posted by Darkblade. Send him a thank you PM if you find it useful.
http://gtaaquaria.com/forum/showthread.php?t=6738

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## Consigliere (Jun 11, 2009)

Its BGA as stated above. I'm pretty sure the cause of this outbreak is due to slow growing plants with excess CO2 in the water column.


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## Zebrapl3co (Mar 29, 2006)

OH ok, only glance at the post and then jump to the picture. Yes, its blue-green alage (BGA). Usually a sign of poor water condition (not neccessary poor filtration as it could be the result of poor water circulation.)
Make more frequent water change and scope those stuff up should help. If you don't have any inverts in your tank. Squirt Hydrogen peroxide or Seachem Excell directly at it will help kill it off.

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## PPulcher (Nov 17, 2006)

I've had the BGA (cyanobacteria) in my tanks a few times. I had a piece of very old driftwood that seemed to seed it. I've put the driftwood in the garden, instead 

I haven't used Excel on it, but I had decent luck with peroxide (1 ounce of household hydrogen peroxide per 10 gallons of water ). In a particularly bad case I resorted to using antibiotics (erythromycin) see: http://www.malawicichlidhomepage.com/aquainfo/algae_erythromycin.html


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## Red (Aug 20, 2009)

Thanks for the suggestions, I've got more options now than when I first discovered the problem

I have BGA on a piece of driftwood - I thought I might just boil the wood in water but may just get rid of it to be safe (good excuse for visit to LFS). The outbreak seems to be localized to the front of the tank and the largest piece about the size of a quarter the rest is just pebble sized flecks on the substrate. I have no inverts just plants & fish so peroxide is OK. I have been scooping up daily but realize that is only a temporary fix.

Is there a way of determining water circulation (food dye?)?

Does the hydrogen peroxide need to come into direct contact with the BGA, if so what's the best method of applying?


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## Calmer (Mar 9, 2008)

Red said:


> Does the hydrogen peroxide need to come into direct contact with the BGA, if so what's the best method of applying?


Use a syringe or a syringe with airline tubing attached to direct the hydrogen peroxide to the affected area. http://en.wikipedia.org/wiki/File:Syringe.jpg
More information here:
http://www.gpodio.com/h2o2.asp


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