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The Role of Gas Exchange in our Aquarium(s)
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By Tommy Gun at 2007-12-19 19:46
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[CENTER][B][U][FONT=Times New Roman][SIZE=3][COLOR=blue]The Role of Gas Exchange in an Aquarium[/COLOR][/SIZE][/FONT][/U][/B][/CENTER]
[B][U][FONT=Times New Roman][COLOR=blue]Abstract[/COLOR][/FONT][/U][/B]
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[SIZE=3][FONT=Times New Roman]After noticing that one or more of our fish are behaving abnormally, rather than coming to the immediate conclusion that some sort of illness or injury is to blame, it is always best to look at one of the factors we have the most control over – water chemistry. The following information and ideas have been compiled to help us better understand the role of dissolved oxygen within our aquarium water, how we can control gas exchange, and the benefits of doing so. [/FONT][/SIZE]
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[FONT=Times New Roman][COLOR=blue][B][U]Wait a Minute…What exactly is Gas Exchange?[/U][/B][/COLOR][/FONT]
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[FONT=Times New Roman][SIZE=3]When speaking of an aquarium, regardless of whether or not it is a freshwater, brackish, or saltwater tank, gas exchange refers to the process of releasing carbon dioxide (Co2) from water while at the same time, replacing it with oxygen (O2). As I am sure you have guessed, even though our fish utilize gills versus lungs, the byproduct of their using O2 to ‘breathe’ is the same as us land dwelling creatures…they create Co2. However, in water, oxygen levels can be depleted over time enough to literally suffocate your fish, leading to death.[/SIZE][/FONT]
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[B][U][FONT=Times New Roman][COLOR=blue]How do I Ensure Gas Exchange Occurs?[/COLOR][/FONT][/U][/B]
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[FONT=Times New Roman][SIZE=3]Luckily, promoting gas exchange is often times as easy to do as it is important to do. In general, all a hobbyist needs to do is apply some method which will ‘churn’, agitate, or otherwise disturb the tank’s surface water. Of all methods available, these are the most common:[/SIZE][/FONT]
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[U][FONT=Times New Roman]Air Pumps and Air Stones:[/FONT][/U]
[FONT=Times New Roman][SIZE=3]I am sure that most all of us are familiar with air stones and air pumps, in fact, I am willing to be that more than two thirds of us are using one or more right now. That said, I am also willing to bet that a good percentage of hobbyists who use them believe they are beneficial because they pump air directly into the water, which is not exactly the case. In reality, the action created when the pockets of air provided by the air pump and air stone hitting the surface is what really oxygenates the water. This is important to know because it may help us place our air stones in order to gain the most benefit as possible.[/SIZE][/FONT]
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[U][FONT=Times New Roman]Filter Returns[/FONT][/U]
[SIZE=3][FONT=Times New Roman]For those of us who use HOB filters (hang-on-back), we may actually be gaining multiple benefits above and beyond the original purpose of filtration. In fact, one of these benefits is certainly gas exchange because most HOB filters return water to an aquarium such that, again, the surface water is disturbed. However, for those of us who use canister filters, we have a very strong ability to gain that same benefit. One way to do that is to focus the return flow from a canister filter so that it also disturbs the water by using certain plumbing attachments. In fact, in both my FW and SW tanks, I use a spray bar with the holes pointed towards the surface water in order to promote gas exchange across the widest area as possible.[/FONT][/SIZE]
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[U][FONT=Times New Roman]Power Heads and Misc. Water Pumps[/FONT][/U]
[SIZE=3][FONT=Times New Roman]By now I am sure you notice that the ‘theme’ here, so I will not dwell on the subject too much other than to say many hobbyists, including myself, employ water pumps and power heads in order to agitate a tank’s surface water, thus utilizing another method of promoting gas exchange.[/FONT][/SIZE]
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[B][U][FONT=Times New Roman][COLOR=blue]How can I be Sure that I my Water is Oxygenated Enough?[/COLOR][/FONT][/U][/B]
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[SIZE=3][FONT=Times New Roman]Since most, if not all, of us do not own any sort of scientific equipment which will tell us exactly how much oxygen is dissolved within water, we need to rely on other indicators and observations in order to make a judgment call as to if we are doing enough to promote enough gas exchange to supply oxygen to our fish.[/FONT][/SIZE]
[SIZE=3][FONT=Times New Roman]Probably one of the best indicators we can use are our fish themselves. For example, in the photo below you can clearly see that all of the fish in this tank are literally gasping for air at the surface of the water; where more oxygen is available. This is an extreme example of course; however, it does give a good example of what can happen if we do not consider gas exchange fully.[/FONT][/SIZE]
[CENTER][FONT=Times New Roman][SIZE=3][IMG]http://i96.photobucket.com/albums/l162/tommygunnz76/graphix/LackofO2_0001.jpg[/IMG][/SIZE][/FONT][/CENTER]
[SIZE=3][FONT=Times New Roman]On a less dramatic note, we can watch the respiration rate of our fish often with the intention of trying to notice if our fish are breathing hard or gasping. While this could also be a sign of other issues, as long as we are prepared to react quickly, attempting to increase the dissolved oxygen available to our fish is always a good idea. In my home, mostly because I have spare or extra equipment from previous set ups, I have at least one air pump and air stone for each tank that is running right now. The reason I kept that equipment all this time is because of the exact topic we are talking about right now…having the ability to quickly increase the gas exchange rate of a tank in a hurry. In fact, the photo above is one that I took of my own tank a couple months ago. [/FONT][/SIZE]
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[B][U][FONT=Times New Roman][COLOR=blue]Conclusion[/COLOR][/FONT][/U][/B]
[SIZE=3][FONT=Times New Roman]While there are many methods of promoting gas exchange, including those not mentioned above, the primary concern for all of us remains the same – to ensure that there are adequate levels of dissolved oxygen in our water – with one important consideration being the addition of an air stone may not prove sufficient in every case. [/FONT][/SIZE]
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