Optimal Surface Agitation

[Alex121]

Hi, I was wondering if anyone has any links to a video showing the ideal surface agitation for a High Tech Tank? I understand the idea higher gaseous exchange+ higher injection rate = quicker to equilibrium + more stable however not sure what is too much? Any help would be much appreciated.

 

[Libba]

Good question. You would really need to see videos of people's tank which demonstrate it. In fine tuning my own surface agitation and CO2 injection I've noticed that I can get away with more surface movement than I had anticipated.

 

[jaypeecee]

Hi @Alex121

Starting with your equation:

higher gaseous exchange+ higher injection rate = quicker to equilibrium + more stable

Higher gaseous exchange will oxygenate the water and lower dissolved CO2. Higher injection rate will increase dissolved CO2. But, if gaseous exchange at the surface is taking place faster than the rate at which CO2 is being injected, it's going to take a long time to reach equilibrium. Agreed? So, we simply need to ensure that gaseous exchange at the surface is minimized whilst ensuring that oxygenation of the water is maximized. With a bit of experimentation, you will arrive at the right balance. In order to guide you, the following link may prove helpful:

9.1. Summary of Aeration

aquariumscience.org

Don't be afraid to shout if I've made any errors in what I've said above. It's been a busy day!

JPC

 

[Zeus.]

SURFACE AGITATION & GASEOUS EXCHANGE IN CO2 INJECTED TANKS well worth a read also IMO

 

[Alex121]

Thanks everyone, interesting reads indeed, I have been experimenting with different methods of surface agitation trying to get it right. I have noticed when I use a surface skimmer attached to a filter inlet for example this seems to drive off a ton of co2, what's people's opinion on running skimmers 24/7 like this?

 

[Zeus.]

When injecting CO2 it is best if you think the CO2 is free, only then will you e it to its full potential IMO

 

[jaypeecee]

I have noticed when I use a surface skimmer attached to a filter inlet for example this seems to drive off a ton of co2, what's people's opinion on running skimmers 24/7 like this?

Hi @Alex121

Interesting observation. I guess it's not surprising that the surface skimmer has this effect. It will draw water in that has both free CO2 and carbonic acid (H2CO3) in it. I'm not sure exactly what reactions will take place as this water passes through the filter. How did you arrive at the conclusion that "this seems to drive off a ton of co2"? Are you able to estimate how much CO2 is lost?

JPC

 

[Victor]

 

[Victor]

The video above is the surface agitation of my plated tank. I think it should be strong to ensure good gas exchange.

 

[Alex121]

Thanks again everyone, To answer your question @jaypeecee I have tried running just a normal filter inlet and the skimmer and when the skimmer is connected I need to inject way more CO2 to get the same PH drop/ DC color. I would estimate probably using around 3/4 to twice as much co2 with skimmer attached. You can clearly see it increases the surface agitation a lot however as you suggest perhaps the way it draws in the top layer of water is always having an effect.

Interesting to see your tank @Victor that is a lot of surface agitation! It would be interesting to know how much CO2 you get through?

Thanks for the video @zeus that is really clear, I think I am getting there with it now I initially was just taken by surprise how much CO2 was needed having never run a large rimless tank before but now realise with my set up you need to be blasting it in there!

 

[Nick potts]

Thanks everyone, interesting reads indeed, I have been experimenting with different methods of surface agitation trying to get it right. I have noticed when I use a surface skimmer attached to a filter inlet for example this seems to drive off a ton of co2, what's people's opinion on running skimmers 24/7 like this?

I noticed this also.

Without the skimmer attached and running a standard inlet, I get an almost yellow DC, attach the skimmer and I need to increase bubble count as the DC goes deep green.

Not sure how it works but as also mentioned above I find it best to ignore how much co2 i am using and just try and get optimal levels.