CO2 Injection/Diffusion

[SQUEAK]

Hello all,

It has been a while since I've really done anything constructive, but I have a question to those of you who use CO2 injection systems. First, how I do it, and have done it:

First method: simply bubbling CO2 into tank using yeast/sugar. Most CO2 is lost through this system, not very effective. Improved by using a passive diffusion bell, however I have read that passive CO2 diffusion is not very efficient, and at most will obtain a concentration of approximately 10 ppm.

Now, I use essentially the same system, but with a small powerhead 'blowing' water past the bottom of the diffusion bell, to catch a small eddie current within the bell, and hopefully the faster moving water will help diffuse in some more CO2.

I have read, but not tried, of some people rotating the output of the powerhead to point downwards into a short tube, and then to bubble CO2 into the tube (so the bubbles will be trying to 'move' opposite to the direction of water flow). I obtained this idea from the articles section of petfish.net/articles.

I'm interested to know how folks on this forum regulate CO2 levels in their tank, if they do inject CO2 at all. My plant experience (and horticultural abilities in general) is rather poor, unfortunately - I could kill a rock . Anyways, just curious - I hope to some day achieve the level of planting that some folks on this site are able to achieve - my tanks are mostly composition of a lot of stem plants, giving it a somewhat 'weedy' look.

[SQUEAK]

I just noticed in another thread that Freddy (user fc) http://www.killies.com/forum/viewtopic.php?t=3431 suggests that using a ceramic diffuser is a bad idea with DIY set ups, I guess the pressure will become too much - it is a good thing I read that, I literally have a ceramic diffuser being mailed to me right now. I will have to avoid using that.

Cameron, or anyone who might recognize the spiral diffuser on his tank, could you let me know how well that diffuser worked for you, and where you obtained it from? It looks like it would be an efficient way to keep the CO2 in the system for an extended period of time, however I haven't found any spiraling diffusers without the ceramic plate. Sorry, I would normally private message for this, but I do not know your user name. Thank you in advance for your time.

[Desmond]

Hi Peter,

For me, I am also using DIY CO2. My reactor bottle is connected to a bell in which my outlet pipe is slightly directed towards it so that the water will get mixed with the CO2 and it is working fine.

I bought a spiral with a ceramic diffuser too, but I am unsure of whether to use it. Not quite clear with what Freddy mentioned regarding DIY CO2 having only a low pressure. Is it due to the low pressure, the gas will not be able to escape through the ceramic Someone please enlighten me

[SQUEAK]

Desmond,

It sounds like we have similar setups. I think I have seen the type you are referring to - is it possible to pop the ceramic disk out?

My guess would be that the pressure in the soda bottle (or whatever bottle you happen to use) would become greater and greater, as the ceramic disk would diffuse slowly. The increase of pressure will eventually lead to a rupture, either in the cap itself (warping of the cap), or via the bottle exploding - the worst case. A pressurized CO2 system has to be stored in metals that are far more resistant to the pressure, and won't explode.

I hope that makes sense, it is very late at night for me, so my writing may not be very clear.

[FC]

I bought a spiral with a ceramic diffuser too, but I am unsure of whether to use it.

Hi Desmond,
The home-made DIY CO2 does not have enough pressure because the CO2 is produced by the naturally fermentation process - through breath of the micro-organsm which are consuming the glucose of the sugar solution. The pressure you get are the sum of their "lungs" pressures.

Your lung's pressure is certainly stronger than theirs, so do this experiment: Try blowing the spiral diffuser. You would get a feel of the pressure needed for the air to pass through the ceramic coin.

[FC]

Cameron, or anyone who might recognize the spiral diffuser on his tank, could you let me know how well that diffuser worked for you, and where you obtained it from?

Hi Peter,
Cameron's user name is "Happy Camper".
Spiral (and ladder) diffuser is quite efficient, about 70% compare to a good reactor. If you look closer to a proper design/made spiral diffuser, it has a small opening at the base to allow water in. As the CO2 bubbles rise up throught the spiral, it create a vacuum effect at the bottom, thereby sucking in fresh water. From here, the CO2 works naturally in the spiral, mixing and dissolving itself with the continuous in-flow of fresh water.

KL, if you are reading this, can you kindly post the pic of your spiral diffuser? Zoom in to the base of the diffuser to show the water inlet part. Thanks!

Note that the spiral used with ceramic are gimmick. There is no hole at the base. The spiral there has no role in helping to dissolve the CO2 as no water is introduced in the process.

Since you have a small pump, you may also consider using reactor (internal or external), see this thread for example of reactor http://www.killies.com/forum/viewtopic.php?t=3300.

[SQUEAK]

Well, that makes for a rather silly diffuser (the ceramic ones). I suppose then the only advantage that has to straight bubbling throughout is that the surface area is massively increased (in theory). I guess I need to look for one of these reactors, or something similar to it. Thanks for your help Freddy!

[Desmond]

Hmm. That means i wasted my money twice! I broke the first one and got another ceramic diffuser. Is it possible to remove the ceramic cap and probably i will place a bell over it to trap the CO2? And secondly, if i am using pressurized CO2, will i be able to use the ceramic diffuser?

[FC]

I suppose then the only advantage that has to straight bubbling throughout is that the surface area is massively increased (in theory).

Yes, exactly, it simply break up the incoming CO2 into multiple tiny bubbles, thereby increasing the surface area/contact to the aquarium water for better dissolve rate.

[FC]

Is it possible to remove the ceramic cap and probably i will place a bell over it to trap the CO2?
And secondly, if i am using pressurized CO2, will i be able to use the ceramic diffuser?

It is useless once you removed the ceramic, the spiral (of this type) does not help in dissolving the CO2 at all. It will be just a coiled tube, look at it again.
Certainly, ceramic diffusers are made sepcifically for pressurised CO2 tank only.

[Happy Camper]

Hi Peter

The spiral diffuser in my tank was sent over by a very kind hobbyist from overseas, I can't divulge his identity as I doubt he would be too impressed with numerous requests for co2 diffusers, sorry. I see that you are in America so it should not be too difficult for you to source these diffusers (ask someone over at aquaticplantcentral.com). They do seem to work quite well with the DIY co2 setup, the plants have no visible pearling but growth is slow and healthy and looking good. This is a nice diffuser to use on a moderately lit tank, for high light you would need to go pressurised in my opinion. Also keep in mind that the diffuser has only been put into my tank a few weeks ago, all that growth has happened slowly over the past year or so using only low light and no co2 at all! All the plants are very easy to grow low light plants like Mosses, Anubias, Java ferns and Crypts. What I'm trying to say is that you don't *need* the co2 in order to have a semi-decent looking planted tank.

I have messed around with diy co2 for quite a while now and I think the best way of diffusing DIY co2 is with Tom Barrs DIY diffuser, you can build one fairly cheaply. You need a small powerhead, and a gravel vacuum can be easily manipulated into the container that holds the co2, this gets your co2 levels up high but not stable. The method works but is erratic IMO, as the co2 levels are constantly fluctuating! Your experience may be different but you should try and build one just to see what it does for your plant growth.

I found these 2 links for you to give you a better idea of what I'm talking about, if anyone else has decent links to Toms DIY diffuser please post them for Peter to see.

http://www.barrreport.com/articles/7...ri-design.html

http://www.barrreport.com/articles/7...ri-design.html

Hope that helps a bit.

Kind regards
Cameron James

[SQUEAK]

Cameron,

I'm very grateful for your post, it has helped me out tremendously - those links were essentially exactly what I need. I'm still trying to figure out what one of the lines is (on the right side, there's a line running which Tom calls the 'Venturi Loop' - I haven't discovered the purpose, or setup, of this loop... is it drawing the water back into the powerhead from the outlet pipe?).

I understand that you cannot divulge the name of the supplier of the spiral diffuser, thank you for letting me know . I imagine an item like that would draw a lot of attention.

Believe it or not, I cannot grow a java fern for the life of me. This would be a 10 gallon tank, with 30 watts of light on it (I can run it at either 15W, or 30W as I choose), right now with a passive CO2 diffusion. The plant just doesn't want to adhere to the rock! I have grown some other plants (apparently, more difficult plants) without a ton of difficulty, but I've failed with java ferns, java moss (yes, I'm quite serious), and amazon swords. Very embarrasing.

Plants I have been able to grow include: rotala rotundifolia, Althernanthera Reineckii, water wisteria (did well for a while, then suddenly the stems just simply rotted...), Myriophillum (still looking for the actual name), and a few others I can't identify. Now, I'm trying to grow some crypts and anubias, but it is the first time at it - we'll see how successful (or unsuccessful) I am. Just to give you an idea of my plant experience - I'm rambling a bit.

I do have a question though: what does pearling refer to? I have heard the term tossed around a few times, and I think it is either a gaseous emission by the plants (collecting on the leaves), or just bubbles that are in the tank that become 'adhered' to the plants. I'm a bit unclear as to what it is, and also what pearling would indicate for plants.

[timebomb]

KL, if you are reading this, can you kindly post the pic of your spiral diffuser?

Sure, Freddy. Actually, there's already a picture of the spiral diffuser in this forum. Here it is:



At the lower end is the water inlet that Freddy spoke of. The way the diffuser works, you pump your CO2 down the long tube that's in the middle of the spirals. The bubble makes a U-turn when it reaches the bottom and rises through the spirals. The spirals slow the ascent of the bubble, thereby allowing time for the bubble to be absorbed by the water. You can actually see this happening because the bubble gets smaller as it rises.

Loh K L

[timebomb]

I do have a question though: what does pearling refer to?

Pearling, to an aquatic gardener, would be when the plants give out oxygen bubbles. It's actually photosynthesis in process. Some plants are known to pearl more than others. Riccia fluitans is the champion pearler of them all, I think.



Loh K L

[SQUEAK]

Loh K L,

Thank you for the pictures, I did not quite understand how the spiral diffusers with the water inlet worked - that clarifies it quite a bit. It might be possible to modify the ones without the water inlet to make a small hole, but I wouldn't recommend anyone without a lot of experience in glass (and knowing what type of glass it is), to even think of attempting it. Glass can be very dangerous if mishandled.

Thank you for the picture on pearling, I have never seen that happen in a tank before. I forgot to add riccia to the plants that I have no luck with .

[Happy Camper]

Hey Peter

The Venturi loop is not absolutely necessary (IMO) if you don't want to build it into your system. Most powerheads come with a small bit of airline that fits into the top of the powerhead, this usually sits just above the water surface and sucks in atmospheric air and then spits it back into the water as small diffused bubbles. On Toms Reactor the airline does not go to the surface but rather back into the co2 holder where it draws co2 bubbles back into the powerhead and spits them out again, so you apparently this is supposed to dissolve the co2 even more and make it more effective.

Java ferns can be funny that way, I have them in all my tanks and some do much better than others, I suppose it depends on the condition of the setup it's in. In your 10 gallon I would recommend to go for 30w instead of 15. Do you dose any fertilisers into your tank? If you have a good fishload then you can safely get away with only dosing trace ferts and a good water change once in a while.

Loh K L's picture of the pearling Riccia is the perfect example of plant pearling. This usually happens in fairly high light setups when the co2 levels are high. What happens is that the water column becomes saturated with gas (co2 and oxygen) until it cannot hold any more. Thus, instead of the oxygen from the plants dissolving in the water they appear on plant leaves as bubbles. Sometimes they even make tiny chains of bubbles (like you see in a champaigne glass). This is indicative that the photosysnthesis process is 'going like a boeing' Although it is a good indicator that the plants are doing well you will probably not see much of this happening within low light setups, even though the plants are doing just as well, just slower growth.

Good luck with your co2 ventures, I hope you come right.

Regards
Cam

[SQUEAK]

Crazy idea, but what that glass diffuser you have reminds me of is a childrens drinking straw. They are often made with a spiral shape, so the child can see the drink rise through the straw, sort of like this:



I've occasionally seen these sorts of straws with a much longer spiral to them. Clip the tops and bottoms of the straw, and fuse a few of them together with a soldering iron, or silicon glue. A small hole right above the bottom of the straw (attach an air line to the bottom of the straw) to draw in the water as the CO2 moves up the line. In theory, with some careful work, the spiral could actually be very long.

Loh K L, Freddy, or anyone with a diffuser similar to the one in Loh K L's picture, do you know approximately what the internal diamter of the diffuser is? My first concern with a straw is that the bubbles are not going to move through the straw very well (adhesion will cause it to stick to the sides, for instance), and I think the spiral straws in particular have a very small internal diameter.

[SQUEAK]

Cameron,

I'll keep it at 30W then. As for the tank itself, it is a 10 gallon tank, with 2 fundulopanchax sjoestedi living in it, and one Ramshorn snail for the cleanup duty (unfortunately, I'm constantly fighting with a rather nasty blue-green 'algae' build up - although it's really a cyanobacteria I think). Not a heavy bioload, but I'm sure having problems with that algae!

The explanation for the Venturi loop makes perfect sense now - thank you for taking the time to explain it. I do use a fertilizer, and water changes weekly of ~20%, and twice a week just cleaning out that dratted slime. For reference, it is a liquid fertilizer called Flourish (made by Seachem), 1ml per week, directly after the water change.

[Happy Camper]

The cyano you're referring to is indicative of unbalance in your tank, and I can see why. Cyano occurs in planted setups when the ratio between N and P becomes unbalanced. Usually the plants use up all the Nitrates and leave loads of P (Phosphate) in the water thus resulting in Cyanobacteria. This would explain why your plants are not doing too well (as there are no nutrients for them to munch on). It ruined a couple of my tanks before I eventually managed to erradicate it. It's actually quite easy to get rid of:

I have'nt tried this on any of my Killi setups so you may want to remove the fish before going ahead with this. Basically you need to give the tank a blackout. Do a nice water change, remove and siphon as much of the cyano as you can from the tank. Add back the new water. Keep the filter going. You need to wrap up the tank with old blankets, towels or plastic sheeting, there should be absolutely no light getting into the tank whatsoever. Keep it like this for three days. Do not peek inside during this stage, not even to feed the fish. After 3 days remove the covers, do another small water change, clean out the filter a bit and your tank should be pretty much free of Cyano.

Your fishload is low and is not enough to sustain good plant growth, you will need to think about adding Macro fertilisers to the tank, Nitrate, Pottassium and Phosphate would be a good start, Seachem covers all of these and should be available to you if you're using Flourish already (what exactly is in Flourish?)

Wait until you've sorted out the cyano and nutrient issues before adding the extra light. Adding extra light now will just make it much worse.

Good luck.

[SQUEAK]

Cameron,

The listing of Flourish is very large.

Nitrogen: .04%
Phosphate .01%
Potash: .06%
Calcium: .17%
magnesium .11%
sulfur: .277%
boron: .001%
bromine: .0001%
Chloride: 1.15%
Cobalt: .00004%
Copper .0001%
Iodine .3886%
Iron: .3886%
Manganese: .0125%
Molybdenum: .0015%
Nickel: .00036%
Rubidium: .0001%
Sodium: .0743%
Tin: .000030%
Vanadium: .00003 %
Zinc: .0004%
Arginine: .016%
glutamate: .09%
lysine: .03%
tyrosine: .019%
choline: .0004%
Inositol: .0011%
Biotin: .0004%
Niacin: .025%
Pantothenate: .007%
Riboflavin: .002%
Thiamine: .002%
Vitamin B12: .00009%
Vitamin C: 1.0%

Whew! That was a bit of strain on the eyes... I do recognize the names that you are mentioning, and yes they are available to me. I actually thought that there might have been too much of a bioload on the tank (as snails can be pretty messy little guys). I have actually been running the tank at 30W for a while now, so it would actually be removing part of the light.

I do have a smaller 5.5 gallon tank (very heavily planted) that actually does well with plants - I can grow plants in there that I completely fail with in other tanks, and I can't even figure out what I'm doing right . I've nicknamed it my plant hospital tank. I start plants out in there to establish root systems before moving them into my other two tanks, or plants that have gotten abused by fish.

That tank functions too well at times, it seems! There are no fish living in it, just a pair of snails. Blacking out the tank for a few days is a viable option, although my 5 gallon tank might be a bit cramped for the pair of killifish. Would it be at all helpful if I posted a couple picture (warning, they will be low quality) of the tanks, so you get a better idea of what I have been growing?