# Really really struggling to get sufficient CO2 diffusion



## Aeropars (9 Jan 2009)

Hi Guys,

I'm so disapointed its untrue and i'mreally starting to think about giving this up.

OK so heres the kit list:
Eheim pro 2 external filter
180l tank
Rhynox 3000 diffuser

Originally I had a aquamas external inline reactor and have never been able to get anywhere near the 30ppm needed for EI. I'd get gas build up and then it would spurt out the filter outlet. There came a point when i couldnt inject any more gas without it wasign co2 and the drop checker never went lighter. Aquamas said my filter wasnt powerful enough for the reactor which makes sence but having upgraded to  a larger reactor from them (after them saying my last reactor was too powerful) i'm not sure I have faith in their products anymore.

So having saw dans tank I decided to get a rhynox 3000 diffuser and pump the gas out from that and into the inlet of the filter giving better turbulence and more contact time with the water. again I'm hitting a point where i'm injecting gas and it cant diffuse quick enough. Dan was using about 1bps from what i remember and the dropchecker was bordering on yellow and his tanks not that much bigger than mine.

So with both ways i'm hitting the same brick wall and i cant overcome it.

I dont know anyone who has this problem and i really cant see what i'[m doing wrong and i'm totally disheartened with it.

Can anyone tell me what i'm doing wrong?


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## LondonDragon (9 Jan 2009)

I am having trouble with my CO2 aswell, I have been leaving it on 24/7 over the last two weeks to see if things also improve, I have used the hydor mini pump CO2 diffusor and a glass stone diffusor, next I am getting one of those external diffusors Ed is building to see if that is a better solution!

At the moment I have lost a lot of plants, and whats is left is not doing too great, so I will be curious what people reply to this thread too.


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## Graeme Edwards (9 Jan 2009)

Hi,

Do not dispair. Are you getting algae or poor plant growth? If not, then theres not much to worry about.
Have a look at how much water surfice turbulance you have and try and drop that down a bit. The other thing you could do is up you KH, by adding KH up. This will give you a higher Co2 concentration in your water. If you mix your own RO or you buy it, this will be really easy to do.

Cheers.


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## JamesC (9 Jan 2009)

Graeme Edwards said:
			
		

> Hi,
> The other thing you could do is up you KH, by adding KH up. This will give you a higher Co2 concentration in your water.



Graeme, where did you get this from? Increasing KH makes it harder for CO2 to dissolve in water, but saying that it's not that noticeable within the ranges that we are used to.

Normally if you find it difficult to achieve higher CO2 levels it's because you've got too much water surface agitation/movement.

James


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## Aeropars (9 Jan 2009)

Thanks for the reply guys.

This is the problem and i dont know how or why i cant get the desired levels. Its funny how i've killed loads of fish by OD'ing the co2 when i used the standard jbl spiral diffuser. I have almost zero suface agitation.

Yes, the plants are suffering becoming weak and brittle so i want to sort this once and for all.

Can anyone give me advice on configuration changes or which part of my setup could be at fault?


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## Dan Crawford (9 Jan 2009)

Hi mate, i'm glad it was my tank that tempted you to alter your methods.

One thing that has become apparent to me last month or so is that i believe that a long time ago AE had an issue with their 4dKH solution, I believe it was much lower than 4dKH so the drop checker changed colour at a much lower CO2 concentration, evidently i had this batch and never knew. My 2kg FE lasted nearly a year coz i was putting very little CO2 in, just less than one bubble per second and this was making the drop checker bright yellow and the plants were great as you saw. I've now changed the 4dKH solution and i've had to wack shed loads more CO2 in to get it lime green, tried a bit further and gassed some fish  So i suppose what i'm trying to say is, are you sure your 4dKH solution is actually 4dKH? presuming your actually using 4dKH and not tank water?

Can you see bubbles on the surface if you look up at it from below the water line? In theory there shouldn't be any because the CO2 should have dissolved before it hits the surface. If you do then try moving your diffuser to a position where the bubbles are either blown around the tank more giving them more contact time in which to dissolve or get it under your inlet.

Also, your dosing EI right? if so, are you sure you're adding the right amount of ferts etc since this could be a major factor in you poor growth issues.


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## Dave Spencer (9 Jan 2009)

I am having trouble distributing CO2 in my 120cm, which is a large size that is new to me, bringing a new set of difficulties.

My staghorn algae says my CO2 is too low, yet my fish tell me it is too high the moment I adjust the regulator. I have come to the conclusion that CO2 is too low in certain areas, so I have added a Hydor Koralia 1 powerhead in the last week to increase movement around the tank.

There are two EX 1200s filtering this tank, but the reactor and lily pipes, coupled with a fairly significant hard scape have left me with insufficient movement in certain parts of the tank.

It could be distribution of the CO2 that is the factor.

Dave.


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## Aeropars (9 Jan 2009)

Hi Dan,

Its actually a batch of my own DK4 solution i made with tom barrs assistance. I'm pretty sure its accurate as the same solution has worked a treat before. with this in mind its given me a good benchmark to measure against as the colour is a lot darker now that what it was.

I do know my flow isnt up to scratch as the eheim alone only gives me 950lph on a 180l tank however i'm not sure that this is the problem but again i've had better results with the same equipment using the JBL spiral diffuser.

There are bubbles hitting the surface but only a few. The majority are being sucked into the filter (as planned) but after a time the buildup in the filter gets chucked out the outlet. The drop checker is a very dark green at the moment, so dark it can almost look blue at times.

I'm currently dosing a more nutrient rich version of PPMD+PO4 but want to have a crack at EI again. The idea was I'd get the co2 sorted and move over to EI in onw deft swoop after testing out the new reactor.

I understand the flow is of importance but surely thats not the root of my problems in this instance?


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## GreenNeedle (9 Jan 2009)

Having battled with my large plantmass for a period of a month or more  I tried many combinations of inlets and outlets, inline diffusers, glass diffusers, needlewheels etc.

In the ned what seemed to sort it once and for all was MORE surface turbulence!!!!  and the Koralia1 wacking up the circulation within the tank.

I have the Koralia1 in the left rear pointing vertically to the right rear.  It is only a cm or so below the water surface and therefore giving a decent amount of ripple along the surface.  The Rhinox 2000 diffuser is lower down on the right rear.  The bubbles come out and half try to rise and then get blow back down and diffuse virtually in this area.  The othe half get caught in the current and move along the right hand pane and half way along the front where they gradually hit the surface.

drop checkers are dark green at lights on and lime green just before lights off.

So my solution was to go from 1100lph (8.8x turnover)at 2-3bps to 2200lph (17.6x turnover) at 3-4bps.

A little wasted but more O in the water at the same time.

AC


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## Graeme Edwards (9 Jan 2009)

JamesC said:
			
		

> Graeme Edwards said:
> 
> 
> 
> ...



Hi mate,

Im no way a chemist, more the artist, but going by the Co2 charts. If the PH is 6.4 say and the KH is 2, then according to some charts, thats 25ppm. Could you not just add KH up providing the PH stayed the same?  Having said that.........does increasing the KH naturally increase the PH, if so, how does that work. What effects do the Carbonates have on PH, why do Carbonates raise PH?
In Areopes case, wouldn't adding RO with  PH of 6 then controlling the KH be a better option? If the water hes using is very hard, then the PH and the KH will be high ( PH7.4 and KH of 6 say ) thats a hell of allot of Co2 needed to bring that ppm into line!

Im not to macho to ask the question, we are always learning.

Cheers.


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## JamesC (10 Jan 2009)

Yep, adding CO3,HCO3 (KH) will raise the pH, so you can't add more KH without the pH rising as well. The problem is that CO3,HCO3 is a buffer and the more of this you have in the water the stronger the water is buffered. So when you add CO2 and try to lower the pH it becomes more difficult to do so with a high KH than it does with a low KH. What tends to happen is that more CO2 is wasted as it comes out of solution into the atmosphere quicker.

But saying that CO2 is still extremely soluble in water within the ranges that are in our tanks and you'd most likely hard pushed to really notice much difference between a low or high KH.

If you get a buildup of gas at the top of a reactor then it's not CO2 but more likely O2 or N. If you get a buildup then note the position of the water line and blast in some CO2 so that the water level drops a couple of inches. Then turn off the CO2 and watch how quickly the water level returns to it's original position. This shows that CO2 is still readily being dissolved. One problem with getting a gas buildup in a reactor is that water flow reduces due to back pressure being created by the gas, so it's best to use a filter powerful enough to prevent a gas buildup. A healthy highly oxygenated tank will normally create a gas buildup in a reactor. A powerful enough filter will then churn this gas up and create small bubbles that will be expelled out of outlet into the tank. Don't think that these bubbles are undissolved CO2 as they probably not.

James


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## Graeme Edwards (10 Jan 2009)

You lots me about here.........


			
				JamesC said:
			
		

> Yep, adding CO3,HCO3 (KH) will
> James


  

Where does this non Co2 gas come from in your filter, if its not Co2 excess? Is that the impeller basically bashing the hell out of the water releasing ( dissolved ) O2 out of the water? But many of us put our Co2 under our inlets, so thats bound to be a Co2 burp as appose to an O2 build up, yes?

As for raising the Co2 levels in the tank. Either go to RO,so you can control the KH better, or just turn the Co2 up.

Having said all this. If you ( Areopas ) are have good plant health/growth, then there is nothing to worry about........is there?

Cheers.


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## Ed Seeley (10 Jan 2009)

It seems like a circulation problem Aeropars to me too.  I'll second Andy's suggestion of a Koralia too.  Mine does an excellent job and I don't find it very cumbersome in the tank at all.  You can see my positioning in this photo,




This is the left hand side of my tank.  To be honest I find the diffuser more distracting than the koralia!!!  Shame I can't fit a CO2 reactor on this as all the filtration and everything is within the tank!


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## Superman (10 Jan 2009)

My own personal view is that seeing the bubbles from a ceramic diffuser in the tank is a bit ugly and so moved from using a Rhinox to an aquamas inline reactor. Now all the diffusion is done out of the way and my external doesn't push the co2 bubbles back into the tank. I do have the largest aquamas reactor I could find and maybe as it's so big it can cope with high co2 injection, as in a smaller one with the same flow rate, there's not much room for the gas in there. Therefore, I think it's very efficient and very tidy.

I myself have the 4dkh solution from AE and whilst I'm not saying that it's incorrect, I find that recently even though the drop checker is green, I've increased the co2 injection after reading some of the articles on the barr report. Now the drop checker is still the same colour but the plants seem to be doing better.


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## JamesM (10 Jan 2009)

I'm struggling too.. have been for quite some time now... I'm going to try a reactor from Ed, but in the meantime I'm back to using the Boyu diffuser on the filters intake. I've also upgraded the filter to an EX1200 with nothing but sintered glass media. If this doesn't work the whole lot is going on fleaBay as my wife is ready to kick my rear end over the money I'm spending


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## fourmations (15 Jan 2009)

hi all

i have a fairly small tank 36" x 12 " x 15" 100l approx

i bought the really small interpet internal filter (mini pf)
as they were in the bargain bucket in the lfs,
i took off the filter media housing and was left with a powerhead with suckers
and a sort of shallow chamber under the impellor

my co2 is going to an eheim plastic "airstone" almost buried in the substrate
and the filter head is  only about an inch directly above, all stashed behind a rock,
this mashes up the already fine bubble and fires them around the tank well

anyway this little powerhead is out of a tiny, tiny filter but can still mash up 4bps
it obviously not getting slowed by media and with the position of the diffuser 
directly under, the bubbles cant go anywhere else, this may work for you

on a related note, whats the deal with this type affair, is this a good option
http://www.youtube.com/watch?v=bg7fleqhM9w&feature=related

regards


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## scottturnbull (21 Jan 2009)

If the filter is struggling to swallow CO2 bubbles at 1bps, maybe the diffuser is too close. My diffuser is to the side of the intake. About 2/3rds of the bubbles - the finest ones - are sucked into the filter, silently. The larger bubbles just percolate up to the surface. My filter doesn't even make a noise, or ever splutter. If you place the diffuser so only the finest bubbles are sucked in, you should be able to increase the bps without having the filter stall on you, since the fine bubbles dissolve much quicker than the larger ones. I've resigned myself to wasting about 1/3rd of the bubbles my diffuser (Rhinox 1000) produces.


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