# CO2 issues



## Buszmann (18 Jun 2013)

Hello,
There is lots a good info out there for CO2 issues and I tried to piece various threads info together to cover my situation, but it wasn't going perfectly.  So here we go.

I have an 80g tank with pressurized CO2 currently delivered via a glass diffuser with ceramic plate.  I placed the diffuser under the inlet to the return pump and the CO2 is distributed in the tank through a spray bar.  My problem is that I cannot get my drop checker to go green (yes I am using 4dkh solution). Running at a constant bubble stream (can’t even count bps) I can manage to get the checker to a dark green.  The trillions of bubbles coming out the spray bar are very very tiny and float in a barrel roll type motion in the tank seemingly endless.  Do I need a better diffusion method? Or is agitation my only problem?

I know I have a boat load of agitation. My spray bar agitates the surface (currently has slight upward angle). The overflows are packed with bio balls so that the water doesn’t splash down the spillways at least.  Someone once told me that it’s okay to have water trickling down the bio balls as long as the water doesn't fall and splash onto them.  The refugium below the tank (21g) has quite a bit of surface agitation as well when going from one compartment to the next before getting pumped back up to the tank.

I can get a diagram going or a few pics if needed.  Any thoughts and comments on where I should focus my efforts are appreciated.

Thanks!


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## IanD (18 Jun 2013)

Hi. I'm new to co2 injection myself but is dark green so bad? Is the tank heavily planted? Is everything growing well?


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## foxfish (18 Jun 2013)

I would suggest it is your overflow & sump!
Think of pouring a class of fizzy drink over your overflow, down through the bioballs & into the sump, there would not be much fiz (C02) left!
You can expect to use far more gas when using a sump, if you have a plentiful & cheap supply of gas then no problem - just turn it up!


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## Buszmann (19 Jun 2013)

Currently my plants are growing, but very slowly.  Plenty of yellow leaves around.  By dark green drop checker, I mean its bluish-green.  I have algae growth stemming from lack of CO2 I assume.

Good point foxfish, I agree.  Do you have any innovative ideas to decrease the gas loss?  What if I filled my overflows with sponge instead of bioballs?  I don’t want to be dropping my life savings into CO2 refills.  Also, if I pump the CO2 into the water faster, do you think I’d need a more effective way of diffusing it?


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## foxfish (19 Jun 2013)

Sumps by their design are not to bad on C02 especially if you cover the top but the overflow is a problem!
One way is not to feed so much water through the sump & use a separate pump circuit to get the desired flow & possibly include an inline atomiser in the line.
A needle wheel pump in the sump will diffuse the gas very efficiently but wont stop it getting wasted down the overflow.
A needle wheel pump & a big bottle of gas would work!!


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## Andy Thurston (19 Jun 2013)

You could shortern overflow by around 10cm and add a float valve in sump to overcome co2 loss in the overflow


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## foxfish (19 Jun 2013)

Hi Andy, tell me that again?


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## Andy Thurston (19 Jun 2013)

Then overflow remains full of water and does not gas off. Auto top up not possible like this though


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## foxfish (19 Jun 2013)

I am sorry mate but I just don't get your meaning... shorten what part of the overflow?


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## Andy Thurston (20 Jun 2013)

Sorry for delay foxfish my internet is dodgy and it can be hard to explain in words. I was thinking like this

 sump design - no CO2 loss - noiseless

It does depend on the design of the sump but you can reduce the amount of co2 lost


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## Buszmann (20 Jun 2013)

Thanks for the ideas guys!  I blasted the CO2 big time (straight foxfish style) yesterday and pointed the spray bar more parallel with the water surface and got the drop checker to turn a healthy lime green    I don't think I can afford this gas usage long term, but it can cover me until I get my plan below complete.

So my plan goes as follows:
1 - Shorten the overflow (my only concern is that I don't have 2 holes drilled and I don't feel comfortable drilling one so I don't know what to do about the safety pipe yet..)
2 - Add an inline diffuser (not sure if I will just put it on my return pipe or do the needle pump)
3 - Find a cover to top the sump

Thanks again,
Alex


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## foxfish (20 Jun 2013)

OK but that is hardly a one hour DIY job!
My main concern would be the set valve that allows the level to be maintained as it would only take a decrease or increase in pump speed to effect the design!
My own sump is fitted only 25 mm below the main tanks water level but that is also something that has to be done during the tanks initial design.
There quite a few successful sump fed tanks on the forum ... you just need loads of gas!


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## Andy Thurston (20 Jun 2013)

I was wondering about second hole in tank too. It could look messy but you could put a tee below control valve for safety pipe then you only need one hole. Also if pump failed tank would drain to the same level as the lower of the two pipes, so unless you have a wier in tank you could have a flood to deal with. 
 The 10cm in my earlier post might be too much. But it needs to be far enough below surface, so it dosent suck air in. 
Have a look a "5 foot hole in wall journal", its a marine to high tech conversion too


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## foxfish (20 Jun 2013)

Yep the hole in the wall is cool but uses 7kg of C02 every 8 weeks.
I use about 2 kg every 9-10 weeks on my 200l but I used to use double that when my sump was under the tank!


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## bluemoon280 (20 Jun 2013)

The hole in wall is 750 litres in total. The gas cylinder I think is 7kg but it might be 5kg.  It's usually 8 to 10 weeks to replace and the main tank is open top at the mo. 

I pay £15 for an exchange so works out not too bad.  Covered sump is a good idea and make sure the levels in the sump make as little agitation. 

My weir and overflow is noiseless and similar to the one linked, tho it has no valve on the return, only on down pipe. So I lose minimal co2 from there. 

Biggest issue I found was getting enough co2 dissolved. Rather than just bubbling to the surface. 

I have just changed my reactor to one similar to the ap5000.   This has a small pump inside the reactor and I feed the co2 into the feed pump. Normal impellor rather than needle wheel. I find em too noisy in freshwater.  My aim is to make as much co2 dissolve before its lost. 

Hope that helps


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## foxfish (20 Jun 2013)

Planbrains 500l tank uses an overflow device & sump & needle wheel return pump (& a lot of gas) & is one of the most spectacular tanks around!
"Dutch something or the other" 120 Gal | Page 24 | UK Aquatic Plant Society
I use my own design reactor (in my sig link) to dissolve the gas but I have been using needle wheel pumps for many years too.


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## Buszmann (20 Jun 2013)

Yeah I am good for the big DIY project.  I have to replace the bulk heads and drain hoses soon anyhow so this will just be a step further than that.  I, like Bluemoon did, was thinking I'd put the valves on the drain hoses to control the water hieght in the overflow. I am thinking of drilling a hole on the side of the tank in the overflow and put in a bulk head there and pipe down to the sump for a safety pipe.  That way if I screw it up i can do a minor patch job and not worry about it draining the entire tank with a hole at the bottom. 

I was looking at Foxfish's DIY reactor and thinking that would be something I'd like to do.  I think that will be 100 times more difficult than the silent overflow project, so I'm going to put that off for now.


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