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hey guys,

I have my 110 hightech high light tank up and running and im seeing some dead spots that could use some directed flow. i have a single 300gph power head in the tank now and was thinking about adding one or maybe two more. Ive read tho that water movement depletes Co2 and adds oxygen, i thought as long as i dont break surface tension im good.

thoughts or input. thanks!
 

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If you increase circulation, you'll cause some loss of CO2. Since this is a high tech tank, you solve that by increasing the CO2.

I use a pair of 500 gph JBJ Oceanstream Circulation Pumps and a Duo Wavemaker (available as a complete package) on my 90 gal planted tank and they are there for the same reasons you want them, to eliminate dead spots.
 

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Any loss of CO2 can be compensated for by increasing your CO2 injection and the addition of O2 is a good thing for all of your tanks inhabitants. A good vigorous surface ripple, short of causing splashing, is a good way to increase O2 levels.
 

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Essentially by moving water across the waterline it causes more water to come into contact with teh air and makes for higher gas exchange, especially when its from the bottom to top. People have reported better gas exchange then using a spray bar by doing this.
 

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Running a 56 gallon column. My Fluval 301 outlets toward the surface, such that I have some rippling effect. Having O2 is important and as previously noted, you can turn up you CO2 if needed. Lower in the tank I use Tunze Nanostream circulation pump. This strategy has worked real well!
 

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Your tank out gasses CO2 because of the higher partial pressure of the gas dissolved in the water than in the air coming in contact with it. The higher the difference in the partial pressures the faster the transfer of CO2 from water to air will take place. If the water was not moving at all then the water near the surface would have less CO2 in it than it would at depth. Dissolved CO2 molecules would have to be passed from the depths up through the water column to the water/air interface before they could pass out of the water. Thus the rate of out gassing would be relatively slow.

Since no water movement is not desirable in a planted tank the moment you begin to circulate the water the you begin to bring water with higher CO2 partial pressures in contact with the surface and thereby increase the out gassing rate. Disturbing the surface tension of the water reduces or removes particulate and other foreign matter (the scum factor) that would otherwise also impede the out gassing process. So the more circulation and surface agitation the faster the out gassing will take place, but only to the limit of the speed related to the difference in the partial pressures.

One of the simpler ways of slowing down the out gassing process is to raise the CO2 partial pressure in the air that is in contact with the water. A glass top on your tank will achieve this very well. The better sealed it is the better your tank will hold on to its CO2. It is so easy to achieve high CO2 levels this way that you need to be careful of distressing your live stock.

If you aren't maximizing the CO2 being dissolving into the water in the first place then you may be wasting a great deal more CO2 this way than the waste resulting from the increased out gassing caused by greater circulation. Try hooking an in-line disperser to the intake on one of your power heads.

As the folks above point out simply increasing the CO2 flow rate will compensate for any CO2 lost to increased circulation and this is by far the simplest solution.
 
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