# surface agitation



## RudeDogg1 (1 Dec 2010)

How much surface movement can you have befor you start losing your co2? mines rippling but I cant hear a thing so i assume its not actualy breaking the surface


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## Dolly Sprint 16v (1 Dec 2010)

RudeDogg1 said:
			
		

> How much surface movement can you have befor you start losing your co2? mines rippling but I cant hear a thing so i assume its not actualy breaking the surface



RD1 

Its hard to say how much ripple is required! try and aim for a very light shimmer, I surpose you could say that at feeding time if the flake food sinks on its own (no assistance for the feeding fish) it to much - but if it stay on the top and floats around - that about right.

Regards
Paul.


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## ceg4048 (2 Dec 2010)

RudeDogg1 said:
			
		

> How much surface movement can you have befor you start losing your co2? mines rippling but I cant hear a thing so i assume its not actualy breaking the surface


I've got some bad news for you: Probably about 90% of what you inject is lost to the surface. You don't need ripples to lose CO2, that's for sure, but the idea is to avoid accelerating the loss by breaking the surface. If there is any splashing, foaming, gurgling or burbling then you know you've gone too far.

Here is my stock photo for showing how violent you can get the surface without doing harm to what little gas you worked so hard to dissolve:






Cheers,


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## RudeDogg1 (2 Dec 2010)

That pic is way more ripple than I have so should b ok cheers guys


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## foxfish (2 Dec 2010)

I am running 5x tank volume into my sump over a surface overflow, so that involves quite a bit of surface movement.
I point my spray bar down & use internal power heads to further distribute the gas...Also running additional 10 x internal movement!


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## Dolly Sprint 16v (2 Dec 2010)

RD1

Here are some pictures of my surface ripple - virtually flat calm.













Regards
Paul.


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## RudeDogg1 (2 Dec 2010)

I only ask because arnt you ment to have surface movement for fish (atleast I always have had in fish only tanks)


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## Dolly Sprint 16v (2 Dec 2010)

RudeDogg1 said:
			
		

> I only ask because arnt you ment to have surface movement for fish (atleast I always have had in fish only tanks)




RD1 

Theorically you right - surface movement or excessive rippling induces 02 into the water which is good for the fish - bad for the plants as it vents any residual Co2 from the water column - by the time your light come on the DC are blue in colouration "all the Co2 gas from the previous day has been vented". This is why we switch on the gas 1 to 2 hours prior to the lights coming on so the Co2 levels are high with the water column and as soon as the lights come on the plants consume the Co2 through photosynsis and inturn the plants emit o2 back into the water column with the fish consume - hope this helps.

Regards
Paul.


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## RudeDogg1 (2 Dec 2010)

Mines still been pale green in the mornings :s


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## foxfish (2 Dec 2010)

Thats sound quite unusual! You do have fresh  4dkh water in your drop checker?


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## ceg4048 (2 Dec 2010)

No, not unusual at all. This is typical, especially for tanks that are covered.

Cheers,


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## foxfish (2 Dec 2010)

I guess that proves the effects of a sump & overflow system because my drop checker will chage withing the hour of the gas being switched off.


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## Dolly Sprint 16v (2 Dec 2010)

RudeDogg1 said:
			
		

> Mines still been pale green in the mornings :s




RD1

that good then   - this proves you have the right about of surface distrubance - excessive distrubance the gas would vent from the water column.

Regards
paul.


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## ceg4048 (2 Dec 2010)

Foxfish said:
			
		

> I guess that proves the effects of a sump & overflow system because my drop checker will chage withing the hour of the gas being switched off



Yeah, this is a real problem with sumps and overflows. Again, a partial solution for those with sumps is to cover the sump which lowers the CO2 egress from the water. Another partial solution is to minimize splashing within the sump.

In a fish-only tank splashing and recirculating within an open sump generates useful oxygenation for the bacteria. This is how bacterial nitrification ( NH4->NO2->NO3 ) is facilitated. In a planted tank however, plants will directly uptake NH4 thus removing it from the water column. Additionally, photosynthesis byproduct is Oxygen, thereby rendering the technique used in the sump redundant. This symbiotic relationship between plants and bacteria means that you can now reconfigure the sump to minimize CO2 loss by reducing splashing and covering the open sump.

Cheers,


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## foxfish (2 Dec 2010)

Well at one time I used to  look at like this - your sump is an asset to you display but treat your display like a separate entity.
In other words set up your planted display tank with its own Co2 supply, dont inclued the sump with the Co2.
If your tank has a underwater bulkhead then take a feed from this to an external Co2 reactor & return the water back to the tank.
But I dont bother with any complicated sytems anymore - just one simple circuit with an in line diffuser.
My tank runs very sweetly, even the weekly water change does not involve lowing the display tank water level & the once weekly mechanical filter floss change is completely hassle free.
I must say the trouble taken to drill the tank &install the sump was well worth the time & effort even if it does mean a little more gas & more ferts than a sump free tank.


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## bjorn (4 Dec 2010)

Is it better to have less water agitation / movement and lots of tiny bubbles? Or more movements to reduce the bubbles?

I just have this problem now with lots of tiny bubbles from the ADA diffuser on the surface.. and only way to get rid of them is to have more movement from the filter outlet.


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## viktorlantos (4 Dec 2010)

bjorn said:
			
		

> Is it better to have less water agitation / movement and lots of tiny bubbles? Or more movements to reduce the bubbles?
> 
> I just have this problem now with lots of tiny bubbles from the ADA diffuser on the surface.. and only way to get rid of them is to have more movement from the filter outlet.



Cheers Bjorn, maybe i am wrong but the bubbles on the surface is mainly oxygen what the plants release. 
Usually happens when plants feels good and releasing lot of bubbles, and you have just a little movement on the surface.


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## ceg4048 (4 Dec 2010)

Hi bjorn,
             That's a good question. To find a meaningful answer we need to think about just what it is that we are trying to do.

The goal of a diffuser is to dissolve a gas into the liquid water. If I put a teaspoon of sugar into a glass of clear water you'd agree that as long as I can still see the grains of sugar, then it is not fully dissolved. When the grains of sugar disappear it can then be considered fully dissolved.

The same goes for my gas bubbles. As long as I can see bubbles, then I know that the CO2 is not fully dissolved. Ideally therefore, I want the bubbles to disappear.

In the case of my sugar, I can use the teaspoon to stir the mixture and this will force the sugar into solution faster. If I don't use the teaspoon then I have to wait for the grains to dissolve. In the case of the gas since I have no teaspoon I have to wait for the bubbles to dissolve on their own. But there is a problem - the bubbles are on their way up and out of the tank, so what I need is to delay their escape and to keep them submerged for as long as possible, hoping that they will dissolve into the water before they can escape.

Dissolving a gas into water is only the first of two major problems associated with CO2. The second problem is now, having dissolved the gas, how do I get it to all areas of the tank to ensure contact between the CO2 saturated water and the plant leaves? 

This is an issue of distribution and it can only be solved by having enough pumping power to move water quickly to all areas of the tank, especially down low, near the substrate. One also needs to manage the flow from the pump in a way that maximizes the distribution of the pumps energy over the widest possible area.

So lets look at your question again within the context of the strategy above:
Lots of tiny bubbles do nothing if they are at the surface. This is like turning you heating on and having the windows and doors in your house wide open.

Movement is key, because it addresses the second problem of distribution. If the movement keeps the bubbles submerged instead of allowing them to escape to the surface the even better because that addresses the first problem of having enough contact time with water to properly dissolve.

If you are "getting rid" of bubbles by agitating the surface where the bubbles are residing then this is a waste of CO2 and a waste of time because the precious gas you are trying to dissolve and to get to the bottom of the tank is simply evaporating.

Ultimately, you will need to devise a plan using the equipment that you have, or obtain more equipment, to fit with the strategy discussed. Try different configurations and track individual bubbles to see how much time on average the bubbles stay submerged and haw far away from the diffuser they reach before they escape. You can even put tiny pieces of paper (the size of bubbles) in the tank to see where they go in order to help you visualize the flow patterns in your tank. Do they reach the far corners of the tank? Do they travel down low?

Solving the riddle of flow and distribution in your particular tank is probably THE most important project associated with carbon enrichment. Did you follow the 10X rule for filtration/pumping? Have you considered using a spraybar? Have you considered using an external diffuser?

I can guarantee you that about 95% of the problems you will have  are going to be related to CO2. 
If you haven't already done so then click these links or go to the Tutorial section of the forum and read these threads:
Setting up a 'higher' tech planted tank
CO2 MEASUREMENT USING A DROP CHECKER

You can also find more information in the following threads (click the link):
Water flow in the planted aquarium?
co2 circulations?
Difference in drop checker readings in different positions

Cheers,


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## viktorlantos (4 Dec 2010)

cheers ceg, a little back to my ealrier comment (without beeing too off) there are no visible CO2 bubbles in my tank. But a few hours before lights goes off i see this on the surface. Pure O2 from the plants which could not escape because of the minor surface agitation.





as i've seen ealrier CO2 escape quicker from the water even if you have just a little movement. Of course this is only a self experience  

sorry if i hijacked the thread.


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## bjorn (4 Dec 2010)

ceg4048 said:
			
		

> This is an issue of distribution and it can only be solved by having enough pumping power to move water quickly to all areas of the tank, especially down low, near the substrate. One also needs to manage the flow from the pump in a way that maximizes the distribution of the pumps energy over the widest possible area.
> 
> 
> Cheers,



Thanks, that's very helpful! I think my problem is to do with my external filter and not having enough power. I actually put back the original plastic out flow rather than a the lily pipe I bought, it's helped a bit and now just fiddling around with getting the best flow around the tank.

And sorry for hijacking the thread!


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## ceg4048 (5 Dec 2010)

viktorlantos said:
			
		

> cheers ceg, a little back to my ealrier comment (without beeing too off) there are no visible CO2 bubbles in my tank. But a few hours before lights goes off i see this on the surface. Pure O2 from the plants which could not escape because of the minor surface agitation.


Hi Viktor,
      Yes mate, I agree that in your case those are definitely pearled O2 bubbles held at the surface by the adhesion of biofilm. No argument there, but the OP stated:


			
				bjorn said:
			
		

> ...I just have this problem now with lots of tiny bubbles from the ADA diffuser on the surface..


So I interpreted that to mean that CO2 bubbles coming from the diffuser were on the surface. I couldn't detect any indication of pearling from the OP's tank photo or description so that's why I concluded that in his case this was CO2, not O2.



			
				bjorn said:
			
		

> I think my problem is to do with my external filter and not having enough power


Yeah, that's why I mentioned the 10X rule. We generally suggest that you have a total filter/pump rating of 10 times the tank volume per hour. When you have this level of pumping power then you have more flexibility as regards the outflow configuration. You may want to look at upgrading your filter.

I can't see where anyone has hijacked...we're all trying to solve the OP's issues, right? 8) 

Cheers,


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## RudeDogg1 (5 Dec 2010)

on a similar vein how long is it before plants start pearling because i havent had any of that


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## Mark Evans (5 Dec 2010)

here's my surface movement.



just enough to limit any surface scum build up. Dust also gets consumed.


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## waj8 (5 Dec 2010)

I have almost no visible surface movement. If I drop food on the water surface it will migrate toward the overflow so there is clearly some movement. Keeping CO2 dissolved in water is a function of surface agitation, CO2 concentration below the water surface and CO2 concentration above the water surface. You could in theory, completely seal a tank and inject almost no CO2 and get high CO2 concentrations even with lots of surface agitation. This would eventually be very bad for your fish though. You have to try and keep things at a happy medium. Some gas loss from the tank is good, too much loss is bad for your plants or your CO2 budget.


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## RudeDogg1 (5 Dec 2010)

Nice tank


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