About surface ripple... Little bit confused.

plantsgallery

Junior Poster
Nov 29, 2014
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Hi everyone


Today I'v read the article that surface ripple degasses both O2 and CO2.


According to ceg4048 of UKAPS, agitating moves gasses from the water to the atmosphere, not the reverse.


As a result, agitating the water too much in a CO2 injected tank then you lose both CO2 and O2.


Well, that explains Why I have double trouble, poor health of plants+gassed fish.


I always thought that more ripple = more O2 = more CO2, so I've had excessive agitation as much as possible.


Then why do we make ripples if that has nothing to do with more O2?


To prevent too much CO2 build up with moderate degassing? Well it can be achieve by reducing injection rate?Â*


I'm really confused. Maybe I misunderstood.


Thanks.
 
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gsjmia

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Jan 10, 2010
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I am no expert by any means and hopefully some with better knowledge will reply, but as I understand it, the gasses seek equilibrium and the surface is where the exchange occurs. If you have more Co2 in the water than the atmosphere, the Co2 will seek to escape into the atmosphere. If you have lower O2 in the tank than the atmosphere, the O2 from the air will try to get into the water.


The surface is where the exchange occurs and the more ripple or surface agitation, the greater the exchange.


As stated in this video, Co2 and O2 are independent of each other:



Namely, if you have high Co2, it doesn't force the O2 out or affect it at all.


I think the goal is to have good surface movement without actually breaking the surface.


If you have high Co2 and you have strong surface ripple, then you are most likely flooding your water with Co2 and any change in the other variables could throw the Co2 into higher levels and gass the fish.


Some Co2 variables are surface scum, plant load, temperature, bacteria activity. And, when I had a canister filter, when it gets clogged, the flow slows down and the amount of surface ripple decreases which increases Co2 (and if you are right at the edge of what your fish tolerate, the will gasp and you will lower Co2 injection). You clean the canister, and the flow increases and Co2 decreases. When Co2 changes, the plants reallocate its internal resources to accommodate the new levels, but this reallocation of resources causes a slow down in growth, which can lead to algea. if Co2 is constantly changing, the plant stays in reallocation mode more than it should and leads to algae.
 

plantsgallery

Junior Poster
Nov 29, 2014
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Thanks for your sharing, gsjmia.


Wow equilibrium, That is exactly what I missed.


Now I have idea. Please let me know if I head wrong direction.


Usual CO2 enriched planted tanks are high in CO2 and relatively low O2.


Because both gasses seek for equilibrium state, CO2 goes out and O2 comes in.


Surface agitation accelerates this process.


With nice ripple this process stays in reasonable level, amount of added o2 is bigger than that of co2 lose so in conclusion more co2 can be added. no problem.


However with excessive agitation, like bubbling and breaking, this gas exchanges goes too far so too much CO2 ecscape..


As a result lack of CO2 = less photosynthesis = less O2 and less growth = not happy plants and fish.


Just my thinking. Am I right?
 

Marcel G

Banned
Jun 5, 2012
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Czech Republic
As gsjmia says, surface ripple serves as a kind of catalyzer which speeds up the gas exchange rate. But it's not true that when you have high CO2 in water and you have strong surface ripple, you will end up with super high CO2 levels. In the air there is a certain concentration of CO2, and in the water there is also a certain concetration of CO2. Both system tend to balance these concentrations (i.e. reach the equilibrium state). In the equilibrium state (under normal temperature and pressure) the concentration of free CO2 in the water is around 0.6 ppm CO2. So if you have more than that in your water, the CO2 will tend to escape from the water into the atmosphere. When you'll have less then 0.6 ppm CO2 in your water, the CO2 from atmosphere will tend to go from atmoshere into the water ... until the equilibrium state is reached. The surface ripple is only the "means" ... the "way" how to accomplish this process more quickly.


But the surface ripple has another important meaning in high-tech tanks. When you supply CO2 into your tank, its level constantly rises from the equilibrium state to some predetermined concentration (based on the exact amount of CO2 you supply into your tank => the more CO2 you add, the higher its target concentration will be). But the CO2 suppy tend to increase the CO2 level in a steep curve, which means that once you begin to supply your CO2, its concentration will continually rise (under 1 bps its contration will rise more slowly, under 3 bps it will rise more quickly, but still it will keep increasing). The surface ripple ensures that the CO2 concentration stays at a lower and much stable level.


Look at the picture:


It is a comparison of CO2 level in the aquarium without rippling and with rippling of water surface.


You may also read this article to better understand this process: http://www.prirodni-akvarium.cz/en/technikaCO2nastaveni

co2ph_srovnani_en.jpg
 
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plantsgallery

Junior Poster
Nov 29, 2014
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Amazing article! Thanks a lot!


Then the true role of surface agitation is making stable and flattened level? Great!
 

Marcel G

Banned
Jun 5, 2012
173
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Czech Republic
plantsgallery said:
Then the true role of surface agitation is making stable and flattened level?
Yes, I think so.


You waste some CO2 (as with rippling you have to add more amount of gas), but at the same time you gain a stable and flattened CO2 level during the photoperiod.
 
K

kashkettle

Guest
Thank you very much for sharing that and your insights. I too always wondered what the value was. Interestingly I use a single power head for day to day flow and surface exchange but have two reasonable canister filters in place. I have stopped using the power head several days ago to reach a better saturation and notice slightly more pearling. I had hoped that implies a slightly higher CO2 level, perhaps this is where I am going wrong in terms of stability?