# Under water CO2 holder to help dissolving



## max88 (Aug 6, 2009)

My CO2 diffuser/atomizer is not breaking CO2 into small mist bubbles. The bubbles are so large that they get to the surface immediately and escape into the atmosphere.

To help get more CO2 to dissolve into water, I have made a DIY under water CO2 holder, out of a plastic water bottle. Part of the bottle in the middle is removed, keeping only the bottom and the top portions. The two portions are stitched together with twist ties (no metal). A large hole is cut at each side of the shorten bottle to allow CO2 rich water to move to other part of the tank.

The idea is CO2 dissolves better under pressure (deeper into the water), and having a larger contact area with water. The bottle is weighed down to the bottom of tank by gravels (I will need to get some stainless steel nuts and bolts), and held in place by a suction cup. CO2 bubbles are fed into the upside down bottle through the hole.

I would like to share this idea, hope other can benefit. Suggestions welcome.


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## coldmantis (Apr 5, 2010)

what colour is your drop checker?


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## max88 (Aug 6, 2009)

Don't have a drop checker. Mine is yeast DIY CO2, never have had enough CO2 to worry about.


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## max88 (Aug 6, 2009)

Anyone knows where to find stainless steel nuts and bolts for low price?


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## Kimchi24 (Mar 22, 2013)

I wouldn't know about low pricing but I do think any hardware store like Home Depot or Lowes would have it.


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## Darkblade48 (Jan 28, 2008)

I am not sure how effective a passive bell diffuser will be at allowing the CO2 to dissolve. Once the mist is captured and the bubbles agglomerate into a large bubble, the surface area is much smaller, and CO2 may not diffuse as rapidly into the water column (especially since there is no water movement).



max88 said:


> Anyone knows where to find stainless steel nuts and bolts for low price?





Kimchi24 said:


> I wouldn't know about low pricing but I do think any hardware store like Home Depot or Lowes would have it.


+1. Hardware stores will likely have stainless steel nuts and bolts, but not at a low price. You may want to check out stores like Sayal or Brafasco (though they might not be much cheaper...).

Of course, online (if you are willing to wait for shipping) is always an option.


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## pyrrolin (Jan 11, 2012)

I am thinking that the gravel part in the bottom would work the same as a bubble ladder in principle, slowing the travel of the bubbles. I don't know how effective the top part would be.

I use whatever size circulation pump I have handy for my diffusion. My smallest is a 200 l/h tiny pump, I just have the bubbles come out under the intake and the pump grabs it and breaks it up great.


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## LTPGuy (Aug 8, 2012)

max88 said:


> My CO2 diffuser/atomizer is not breaking CO2 into small mist bubbles. The bubbles are so large that they get to the surface immediately and escape into the atmosphere.
> 
> The idea is CO2 dissolves better under pressure (deeper into the water), and having a larger contact area with water. The bottle is weighed down to the bottom of tank by gravels (I will need to get some stainless steel nuts and bolts), and held in place by a suction cup. CO2 bubbles are fed into the upside down bottle through the hole.
> 
> I would like to share this idea, hope other can benefit. Suggestions welcome.


I am also not a big fan of mist type diffuser as I feel that they waste a lot of CO2. I just don't like to waste if it can be helped, not so much the cost.

You're on the right path with this setup, with depth and the bell setup. As Darkblade suggested, it's not the most effective setup as it is passive.

On that note, you can improve the dispersion by diverting your pump water into the opening.

I've tried many ideas including what you have, but I find that there are long term issues. Namely, there are build up of gas, probably O2, which fill up your "bell" until it's full and all your O2 overflow out the opening.

There could be a biofilm build up at the gas/water interface which limit or inhibbit CO2 dissolution and the bell gets fill up again.

I've gone so far as to build a type of syphon that will automatically purge the gas after a certain level. This work well, but I wasn't convinced that the purge gas are O2. The syphon is basically a u-tube attaching to the bell.

The best approach for me with consistent result, that's highly effect, and efficience is by using a powerhead with an aeration port at the output.

The output of the pump goes into an plastic tube/bottle. The flow is forced down and out at the bottom which can be diverted to whereever you want. An airline is connected to the top of the bottle, where undissolved gases builds up, to the aeration port.

This way, any undissolved gases is not wasted. It is not 100% efficient, but I would say 98%+ as on occasion there is a very fine bubble that get blow out of the bottom of the bottle. 99% of the time, those bubbles dissolved in your tank before reaching the surface.

I can post a picture of my setup when the lights are up if anyone is interested.

If you choose to go with your setup, I would suggest that you force some water into your bottle opening. Please give us an update of your setup in the long term. I just want to know if you see similar issues that I faced when using that setup.

It looks like your setup is low-tech which fare better when there are unstable parameters, namely CO2 in this case. In a higher light, not necessarily high tech, unstable CO2 will stress your fishes if you have any, and create major algae issues.

Again, good luck and please update us in a few week and then month on how well your setup fare!


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## Mlevi (Jan 28, 2012)

LTPGuy said:


> I can post a picture of my setup when the lights are up if anyone is interested.


I, for one, would love to see it. I'm toying with the idea of diverting my CO2 into a chamber where I force water to flow into the gas by use of a small pump. I've had a DIY yeast reactor for a couple of months, and am going through the various methods of diffusion to see which one works out best for my tank.

Al.

PS: I don't mean to hijack this thread or anything. I figure that since the topic is DIY CO2 diffusers, we can all share and benefit from max88's experiences.


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## default (May 28, 2011)

I personally love doing a DIY for this hobby, but a big pet peeve and no offense to anyone (strictly personal) - I hate seeing people use a plastic bottle as a long(er) term solution as co2 catcher, diffuser, reactor, whatever people call it.
Just, those bottles are not made of amazing plastic, they are soft and most likely release plastic into your tank.
And when people make filters out of those bottles  way too many times have I ended up on the weird part of YouTube lol.
Ok jokes aside.

This bottle setup just can't work well, darkblade is right as the more co2 builds up the less surface area you will have. And there's no way it's dissolving fast enough for there to be enough space.
I personally really like diffusers/atomizer over everything else (I do have smaller tanks 30g max for planted) and its all about your flow to maximize their effectiveness, even in my inline reactors before some co2 build would get so large the reactor just burps them out and it's almost like not dissolving them at all.
I would try DIY a inline-intank reactor even with a bottle (seen some done really well) using that diffuser as well and that would increase your overall effectiveness of the DIY co2.
Also side note, those atomizers suck.. They're suppose to be good for DIY, but they were a pain. They tend to break easily for no reason by cracking and releasing big bubbles, perhaps bleach it and then inspect the atomizer for cracks, and then maybe it will start giving you finer bubbles, I have a few of those that I keep around to test my co2 and with a pressurized cylinder they give me very fine bubbles all the time.


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## balutpenoy2oy (Feb 17, 2011)

IMHO, Inline atomizer is the best. I am using a DIY one, it is 24" long x 2 1/2" diameter acrylic tubing and no bio-ball or what so ever to intercept the escape of CO2, still I never experienced a burp, almost all of the Co2 introduced were dissolved in water. Or may be not unless I use magnifying lens to inspect it. I am just using 2 bps the most and it seems my plants love this.


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## max88 (Aug 6, 2009)

Thanks all for the replies.

I had high hope this would be a good, zero cost, replacement to the big bubble diffusers. Obviously the passive CO2 bell (Under water CO2 holder) leaves a lot to be desired. Back to the drawing board.


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## LTPGuy (Aug 8, 2012)

default said:


> I personally love doing a DIY for this hobby, but a big pet peeve and no offense to anyone (strictly personal) - I hate seeing people use a plastic bottle as a long(er) term solution as co2 catcher, diffuser, reactor, whatever people call it.
> Just, those bottles are not made of amazing plastic, they are soft and most likely release plastic into your tank.


To each their own I guess. If you know of a cheap source for polycarbonate/acrylic tubing or sheets and caps, sign me up.

Plastic world sells 8' tube for about $20 each in box of 4 or box of 20. Minimum order $500. BA sell 4' tube for about $20. Mind as well buy the reactor and miss out on the fun!

I also haven't heard any health issue with PETE and PP bottles. Point me to a study so I can keep up to date.

Personally, the biggest part about the hobby is the DIY aspect. You can and experiment with life science, physical science, engineering, electronics, material sciences!

Cost is also a factor with many DIY projects, and hence the making use of readily available material for no or very little cost. Just the effort and some tools!

Otherwise, mind as well buy the parts off the shelf.

Mlevi, here is the link to my latest and probably final CO2 reactor setup. The pump not only dissolve the CO2, but also power the 3x10G tanks setup. It's all sitting in the sump so it can be as ugly as me and noone the wiser!

No gurling, near 100% efficiency, effective for long term, and the only maintenance is to rinse the prefilter at the pump input once in a while!

Max, I hope we are not detracting from your post, but you're on the right path. Don't stop tinkering or sharing no matter what!


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## max88 (Aug 6, 2009)

LTPGuy said:


> Max, I hope we are not detracting from your post, but you're on the right path. Don't stop tinkering or sharing no matter what!


Not detracting at all. The posts are what I wanted to happen. I have learned a lot from the posts in this thread, and other threads on this forum. I have benefited more than I can contribute.


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## default (May 28, 2011)

LTPGuy said:


> To each their own I guess. If you know of a cheap source for polycarbonate/acrylic tubing or sheets and caps, sign me up.
> 
> Plastic world sells 8' tube for about $20 each in box of 4 or box of 20. Minimum order $500. BA sell 4' tube for about $20. Mind as well buy the reactor and miss out on the fun!
> 
> ...


Perhaps google would yield some answers for you, a lot of folks in the past always stated how bottles and reusing them was always a concern for even human consumption, plastic does peel off (you can even see this in older bottles) and would end up in the system.
However they're not just consuming the water, they're swimming and living in it.
Sure, small amounts of bpa in the water column won't kill em fishes, but why would you want to place them in water that would contain chemicals that lead to concerns even for humans?

But I agree the DIY factor is probably the best part, but DIY with aesthetics in mind should be considered.
To OP it's a great start, clearly my rant was entirely personal and was full of sarcasm  but I find PVC has always been a great thing to use for these DIY projects, they are affordable and look very nice if done properly. A foot of pvc could cost you the price of a full bottle of water. Get some end caps and drill some holes, you'll end up with a great reactor, and use the atomizer you have inside and this would get you a higher co2 saturation.


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## Mlevi (Jan 28, 2012)

LTPGuy said:


> Mlevi, here is the link  to my latest and probably final CO2 reactor setup. The pump not only dissolve the CO2, but also power the 3x10G tanks setup. It's all sitting in the sump so it can be as ugly as me and noone the wiser!
> 
> No gurling, near 100% efficiency, effective for long term, and the only maintenance is to rinse the prefilter at the pump input once in a while!
> 
> Max, I hope we are not detracting from your post, but you're on the right path. Don't stop tinkering or sharing no matter what!


That is kewl... Next step, I'll be begging you to post a video of it 
Seriously though, your design looks more efficient, not to mention has a smaller footprint, than what I was looking at online. Thanks for sharing your knowledge and experiences.

Al.


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## balutpenoy2oy (Feb 17, 2011)

Here is my set-up for the *in-line reactor*.. . They say actions speak louder than words, to me picture speaks the loudest...


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## default (May 28, 2011)

balutpenoy2oy said:


> Here is my set-up for the *in-line reactor*..


Oh that's cool looking. Is the co2 rig free floating?!


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## balutpenoy2oy (Feb 17, 2011)

LOL, they have bottom supports..


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## LTPGuy (Aug 8, 2012)

default said:


> But I agree the DIY factor is probably the best part, but DIY with aesthetics in mind should be considered.


I totally agree with this, and I also feel strongly the same about aquascaping the display tanks also! Aesthetics and balance really adds to the showcase and bring inspirations. God forbid how many hobbyist have inspired me. Here's an example of a recent display I saw on GTAA...









by anzphil on this post. Simple and sweeeet!



default said:


> To OP it's a great start, clearly my rant was entirely personal and was full of sarcasm  but I find PVC has always been a great thing to use for these DIY projects, they are affordable and look very nice if done properly. A foot of pvc could cost you the price of a full bottle of water. Get some end caps and drill some holes, you'll end up with a great reactor, and use the atomizer you have inside and this would get you a higher co2 saturation.


Agree again, but sarcasm can be dangerous especially through emails or postings as it is hard to tell the tone of the wordings. I try to put as much smileys as possible, like you, without over doing it, but sometime they get missed still!

I've used PVC for my plumbing and overflow and it's great because it's black, and you bare notice it especially when covered with tall bushy plants.

Still, plastic containers are great to use because it's clear, it's easy to work with, it's almost instantly available, and it's FREE. Perfect for DIY projects and trying out new concepts.

My diffuser setup cost me less $1 in materials. The tee for the CO2 and CO2/Air recirculation, and the 10" long pex tubing.

I am not going to argue with you about health issue with PETE, LDPE and PP here, but if you start a thread, I'll chime in!

Just so you know, I've seen a lot of your posts and your plants are amazing! I highly respect anyone who can keep lush plants growth like yours. So there was never any disrespect if any of my comment came out as such.



Mlevi said:


> That is kewl... Next step, I'll be begging you to post a video of it
> Seriously though, your design looks more efficient, not to mention has a smaller footprint, than what I was looking at online. Thanks for sharing your knowledge and experiences.
> 
> Al.


There's a first time for everything, so I will try my first ever video - just for you Al! I'll post it on Youtube through my thread tonight. I am glad to share as like every member that I've came across here. My biggest passion is the DIY, and do it in manners that keep things as simple as possible, as cost effective as possible without compromising performance, and aesthetic. Of course sometime "ugly" can't be helped so it has to be hidden!


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## Mlevi (Jan 28, 2012)

LTPGuy said:


> There's a first time for everything, so I will try my first ever video -


That was pretty kewl!
Puts things into perspective. Thanks for goin' the extra mile 

Al.


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## Fishfur (Mar 4, 2012)

Interesting what's out there on leachate problems with PETE plastics. Not a great deal on google, and mainly about BPA. But generally it would appear BPA leachate is only a problem in bottles exposed to high temperatures, 120F, for at least two hours, or to sunlight for a few months. So keeping water bottles in the car over the summer is probably a bad idea.

PP is different. Very susceptible to UV degradation, and in 2008 it was reported that quaternary ammonium biocides and oleamide were leaching from PP labware, which was affecting the results of experiments being conducted in such labware. This was a Canadian discovery and the government was asked to look into it. Don't know if that happened. If it did, I found no results on it.

But I don't think the possibility of leachates are the only issue. If they break down, especially very thin bottle plastic, you may well get tiny particles that may be consumed by fish, surely not a good thing. And if you get cracking, some cracks might pose a physical hazard to some fish.. such as my ever curious kuhli loaches, who will squinch themselves into any crevice they can find, whether they really fit into it or not. They've kept trying to find an exit from a blind cavity in a chunk of wood for months now. Apparently, they don't learn from experience in this regard.

So called disposable plastic bottles are cheap, for sure. [ I say so called because I disagree with the concept of so many things being disposable ] but I'd prefer not to use them inside a tank. Outside, at least if they start to leak, hopefully you'd notice before there's major damage. If it's starting to peel, recycle if possible.


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