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Equal co2 distribution

nigel bentley

nigel bentley

Member
Joined
20 Oct 2019
Messages
157
Location
Wallington
Hi,
Thought I had good Co2 distribution having a nice light green on drop checker when situated in middle of tank. However, with experimenting as you do? I have found a dead spot back left corner
Drop checker is green but quite dark. I have two questions Is this a major issue and if so can I rectify it? The tank is a1500mm long 100gallon 20" deep. I have spray bars running along the length of back wall. 1/3 of those point upwards for surface agitation, the rest point down at 45 degrees. The Co2 diffuser is on the back wall to the right. I also have an Eheim air circulator on right wall. Sorry for the long winded text, any advice would be much appreciated. Thanks. Nigel
 

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I personally think that your problem is caused by your spray bars pointing in different directions to each other. Some are probably degrading/cancelling the effect of the flow of others. If it were me, I would have all of your spray bars on the back wall, slightly below the water surface, pointing primarily forward, but with an EVER SO SLIGHT upward direction. Just enough to ripple the surface of the water, as the flow projects forwards out of them.

I think this way, you will have all the flow first causing a ripple of the surface for gas exchange, the momentum then carrying it forward until it hits the front glass, and then down to the substrate, and then back around across the bottom of your tank, completing the circle of flow back to the filter intakes. The general direction of flow from all of your spray bars will then be uniform, and augment each other, rather than working against each other.

If your spray bars cover the majority of the length of the back wall of the tank, and you have enough filter power feeding them, I think this should give you very good, and even flow around the majority of your aquarium.
 
I agree fully with aquascape1987's assessment. While it is possible, due to the layout of hardscape and plant mass, that pointing each bar at a different direction may work, typically we want as much water mass moving in the same direction. The momentum of the moving mass usually has a better chance of flowing in the direction we want. I see the same mistakes being made when folks have multiple pumps and they mount one pump on the left wall while the other is mounted on the right wall. The two flows which then are in opposite directions cancel each other out. Spraybar technique depends on coherency of the flow.

See the thread Water flow in the planted aquarium?

In any case, that is the first step, the baseline configuration, after which we can then deviate in order to find the best flow solution.

Cheers,
 
Hi all,

I've often thought about changing my filter outlet to a full length spray bar on my EA 1200 to better distribute nutrients equally around the tank but how does this affect the intake to the filter?
My intake is positioned on the bottom right of the tank so surely this means it's only taking in the same section of water as the flow is circulating in a different direction, would the opposite side be circulating 'dirty' water as it's over a metre away from the intake it won't have much chance of being pushed through the filter

Cheers, James
 
Thanks so much for your relies, I will move the spray bars today. I have also noticed a kink in one of my out pipes. I will also sort this out.

Thanks again Nigel
 
ceg4048 said:
I agree fully with aquascape1987's assessment.
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To be honest Clive, I developed my current ideas on flow from experimenting with my own tanks, after taking pointers from many of your historic posts on the forum, and also your replies to my own flow problems years ago.


EA James said:
I've often thought about changing my filter outlet to a full length spray bar on my EA 1200 to better distribute nutrients equally around the tank
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I personally gave up using Lilly pipes in favour of this method about a year ago, and have never looked back since. I have found flow to be far superior using spray bars in this way, and my results with the plants and algae have proved this to me. I still use glass intake tubes though.

Although most people consider them an eyesore, and consider glass lilly pipes much more pleasing on the eye, I have found that I rarely see my black spray bars against my black background, due to them camouflaging in very well. Also because the angle the tank is viewed from,is 99 percent of the time from above, and not with your head on the same level as the tank (unless you bend down). Even the EA1200 is viewed from above unless you sit down in front of it. This means that the spray bars are completely concealed by the rippling mirror effect of the water surface when viewed even from slightly above. It looks like there is nothing there at all. I also find glass lillys to be sometimes just as much an eyesore, as they are large, strange shaped and more often than not, right at the front of the glass in your direct view. They aren’t invisible by any stretch of the imagination.


EA James said:
My intake is positioned on the bottom right of the tank so surely this means it's only taking in the same section of water as the flow is circulating in a different direction, would the opposite side be circulating 'dirty' water as it's over a metre away from the intake it won't have much chance of being pushed through the filter
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I’m not sure exactly what you mean here, but I think what you are saying is that your intake(s) are in the front bottom corners?
If so, I think the system would work better with the intakes in the corners, right below the spray bars, as you would do with a normal lilly pipe. Not exactly so sure it is because it means only ‘dirty’ water is sucked in, but more to do with being uniform with the circular flow direction you are creating in the tank. Being positioned here, the intakes complete the circle, by sucking in water at the last point of the circle, rather than intercepting water mid point in the circular path you have set it on, as it would do if the intakes were at the opposite side. That’s how I rationalise it anyhow.
 
Hi, i have a little question, if someone can help me ofc. If I use 2 canister, but have only co2 reactor attached to one of the canister. Which away can be co2 good distributed with spray bar along the whole back side of aquarium. Thanks, if someone fixed this.
 
Hi Ivan,
I also use 2 x canister filters with 2x spray bars, but I have a CO2 feed to both of the lines.
Not sure if it is ok to have the CO2 on only one, but the reason I chose to do it this way,was because I wanted even the CO2 to enter the tank evenly at each side, and also didn’t want a mis match in flow output on each side from the two filters. Inline CO2 diffusers and reactors restrict the output of a filter. I figured that having an inline on one but not the other would create asymmetrical output from the filters.

I use a manifold to allow 2 x CO2 feeds from one bottle and regulator like this:



6C447E35-27FB-47C1-BDAA-D6A8E62AB1A0.jpeg
 
I understand that with two reactors must be fine, but because I have one and will be little hard to split co2 on my regulator. I'm using 2 standard eheim Lili pipes pointed in same direction one from right back side with flow to left and other on back left side with flow to the front side. I have and one pump on front left pointing on to the right. Not sure if it's good, but I think it must be good with only one reactor.
 
Ivan Stoyanov said:
I'm using 2 standard eheim Lili pipes pointed in same direction one from right back side with flow to left and other on back left side with flow to the front side. I have and one pump on front left pointing on to the right.
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Do you have a picture of your set up, for clarity? If you have one, it may be a little easier to understand, and someone may be able to help/advise. 😁
 
Sorry mate, It wasn’t your English at all. It’s more that my brain prefers pictures rather than words in order to understand sometimes 😂

What are you using? Spray bars or some other type of outlet?
 
Sorry, I have just fully worked this out now. My brain is not in gear today 🙄.

The flow appears circular on your drawing, but I’m not so sure it will achieve this in real life using the Eheim outlets, and pointing in these directions.

As I’ve said above, I personally would still advise spraybars along the full length of back wall, holes pointing to front of the tank. Very slight upward angle.

Even if your Co2 is only on one feed/one side. It will still distribute CO2 around the tank, even if not quite as efficiently as having CO2 on both filters. But still effectively!

The main reason I did it with two is because I am picky, but I’m sure it would have worked fine with one feed only.
 
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aquascape1987 said:
I’m not sure exactly what you mean here, but I think what you are saying is that your intake(s) are in the front bottom corners?
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I've just taken a few pics to better explain it, always helps IMO.
So the twin outlet, one points down to blast the co2 downwards and then across the front of the glass, the other one is pointing towards the surface for agitation but still in the same direction. The flow then eventually goes around the back of the tank and meets up with the intake so that's my flow pattern!

Kinda difficult to explain in text but i was trying to get at is my flow circles around the tank in that way. With a spray bar the pattern changes, It's hitting the front of the glass then going across the bottom and up the back. So say in my tank for example, with the intake being on the right, how would the water on the left of the tank go through the filter? I know it all gets mixed up in the tank but It's not a direct feed if you like.
Does that make sense?

Cheers
 
Ah I see mate. If that works for you and gets flowing water everywhere then, that’s all that matters really. I would still recommend trying the spray bar though if you get the chance, as you were thinking of it anyway. You could give it a go for next to nothing cost wise.

I get what you mean about using a spray bar and the outlet being on one side only when using one filter. Not sure how much of an issue that would present in terms of there being nothing at the other side to pick up that side of the final phase of returning flow. As you say, the water all gets mixed up anyway, so I would hazard it’s not that much of an issue, but I’m not an expert. Maybe someone else can answer this a bit more scientifically than me in terms of the physics.

But, thats why I chose to use two filters instead of 1, to make sure that I didn’t have an issue in this respect. It’s more about the symmetry of my system, rather than needing the extra filter flow, because let’s be honest my tank doesn’t need the amount of filter power I’m using. Going by the rated flow of these filters, it is turning over 20x an hour, although in reality it will be less than this I realise.
Still, I figured the extra turnover couldn’t hurt, as long as I could control it and it didn’t destroy everything and upset the fish (which I have managed to).

It’s each to their own methods on this, like many other aspects. This is just how I have found success that’s all. I by no means think it is the only way to create good flow however.
 
I'm going to suggest something highly controversial.

If you are using a diffuser and want to know the effects of flow on co2 distribution, turn off the pump or have it at the lowest level you can for a few hours then put multiple drop checkers all over the tank and see what happens to them.

The results might surprise you - because bad flow i.e turbulence excessive / surface agitation can actually decrease co2 in the water.

Having an understanding of co2 distribution in a tank before without flow makes it easier to calibrate it. Sometimes, a well placed powerhead is more effective than upping turnover - as far as co2 is concerned.
 
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Easternlethal said:
The results might surprise you - because bad flow i.e turbulence excessive / surface agitation can actually decrease co2 in the water.
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I think it’s a given that surface agitation causes CO2 to off-gas and leave the water, but is necessary to oxygenate the tank.

So yes, CO2 is wasted by leaving the tank before being used by the plants for sure, but this is why it is fed in at a steady rate to ensure that there is a constant supply available around the plants and to them.
The aim isn’t to be efficient with CO2, but to make CO2 constantly available to the plants throughout the photo period irrespective of how much is wasted... CO2 is cheap, so wastage is not a concern.

Easternlethal said:
If you are using a diffuser and want to know the effects of flow on co2 distribution, turn off the pump or have it at the lowest level you can for a few hours then put multiple drop checkers all over the tank and see what happens to them.
Click to expand...
I think that CO2 would eventually saturate the water like this through the process of diffusion, but I’m not sure how relevant these results would be to the principles of Co2 distribution in a planted tank. If you employed this technique long term, your tank would not be a healthy one, and your plants would not thrive.
 
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