# Straight answer on aeration



## Akiles (Apr 24, 2018)

Hi there,

I have just started my first planted tank (first tank of any kind actually). It's a 30 gallon planted fairly heavily with DIY co2 and a canister filter. The filter is the Fluval 204. Co2 is injected directly into the filter intake. My question is about surface agitation as it pertains to aeration. I have read numerous conflicting things about whether or not an air stone or powerhead is needed. Some say the filter should be enough to provide surface agitation. But there is virtually no movement on the water surface of my tank. It's basically still. I would like to avoid putting in an air stone or something because I don't want more mechanical crap in my tank messing up the aesthetic. 

So my question...how necessary is it really and what's the least intrusive way of getting some oxygen into my tank? I should note it's an open tank. No top.


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## Marten (Apr 15, 2018)

You could adjust or modify the outlet of your canister filter to break up the surface of the water a bit.


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## CRS Fan (Apr 21, 2010)

Another option would be a Hydor Koralia circulatory pump. The are easy to install and adjust directionally. In a heavily planted tank this would help with CO2 dispersion as well.

Best regards,

Stuart


Sent from my iPhone using Tapatalk


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## Akiles (Apr 24, 2018)

Do you mean the output or the input? I was under the impression that the output was meant to be much lower in the aquarium than the intake. But I don't really understand why. I was contemplating raising the input a little to barely break the surface of the water but was worried about excessive air getting into my filter and then evaporation might lead to a situation where it's sucking dry. Did you mean the output though? Because that seems safer to have breaking water level but I'd need to adjust it big time since the mechanism is designed to be closer to the substrate for reasons maybe someone can explain to me.

I will look into that pump as well, thank you. Seems like a good piece of kit. So small according to the dimensions listed on Amazon. 

Are there any devices that operate purely on surface agitation? I'm imagining like a propeller that could attach near the surface and simply disturb the water. Because after all, they say an airstone doesn't introduce oxygen by the bubbles as you might think but by the surface agitation those bubbles produce once they break the water surface. 

Thanks!


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## charlie1 (Nov 27, 2015)

Something to think about- CO2 is very easily out gassed from columns of water, hence too much surface agitation could cause rapid co2 depletion , this is especially so with DIY sugar and yeast co2 production when it`s already a difficult task to maintain proper co2 saturation.


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## EDGE (Aug 24, 2010)

Akiles said:


> Do you mean the output or the input? I was under the impression that the output was meant to be much lower in the aquarium than the intake. But I don't really understand why. I was contemplating raising the input a little to barely break the surface of the water but was worried about excessive air getting into my filter and then evaporation might lead to a situation where it's sucking dry. Did you mean the output though? Because that seems safer to have breaking water level but I'd need to adjust it big time since the mechanism is designed to be closer to the substrate for reasons maybe someone can explain to me.
> 
> I will look into that pump as well, thank you. Seems like a good piece of kit. So small according to the dimensions listed on Amazon.
> 
> ...


Output / Outlet is the return from the filter - where water comes out of the filter. Input is where the filter suck in the water. You can get a "lily pipe". 




Surface agitation / ripple looks more natural than blasting air bubbles in the water.

With good plant growth and CO2, there shouldn't be a need for surface agitation during the day because the plants are expelling O2 through the leaves and roots. At night time, that is a different situation and depend on your bio load. a few smaller fish can get by. a heavily populated fish tank or a couple large fish will probably end up suffocating if they cannot breath from the surface as a last resort.

The "straight answer" is play it safe and add an air stone or some way to create surface ripple / agitation at night.


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## Mick2016 (Jun 16, 2016)

Whereabouts is the OUTPUT of the filtered water (i.e. spout) returning to the tank. If it is near top of the tank's rim, you could lower your water level enough so that the outflow of the filtered water "hits" the surface - causing more ripple. Of course, this is all individual to the design of the actual outtake spout as well as the amount of splash or noise created. In effect, the water release drops into the tank.

I have my H.O.B. filter's spout touch the water's surface so there is virtually no splash or noise. Slight ripple. However, I also have an air stone in the tank.


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