newbie question on flow

filipem

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May 21, 2008
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I currently have a 46 gallon tank that is filtered by a ehiem 2217 and a ehiem 2213. I am thinking about adding more current but I have never used a powerhead or pump before. How do they work and what should I look for?
 

Gerryd

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Sep 23, 2007
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Depends on the type.

It is simply a water pump that goes INSIDE the tank. Once plugged in it moves the water around, with no filtration.

As an example, the Hydor Koralia pumps have a magnet that splits inside and outside the tank.

They have a spindle that allows the pump to be positioned well and in different directions.

They come in different sizes and can really improve flow.

Hope this helps.
 

captain_bu

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Nov 7, 2007
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I put a Koralia 3 in my 50 gallon long tank and it was way too intense. It certainly moved a lot of water but I couldn't find a way to situate it so that it wasn't blowing over any plants, making craters in my substrate, or creating too much surface turbulence. I took it back and got a nano. I agree that it does not move a ton of water like the larger Koralias but I am now able to get a bit of additional flow where I want it. That was my primary goal, I already have two canister filters on the tank so the powerhead is not my primary circulation source. I like the physical size of the nano a lot better too, I found the larger Koralia to be kind of intrusive. In a large tank though I think the Koralias would do an excellent job.
 

schwark

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Aug 18, 2008
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I have a 20 gallon tank with a Marineland Bio 220 filter (up to 40 gallons). How do you really know if you do not enough flow? I know flow relates to oxygen, and I should possibly test for oxygen, but I wanted to get a little more information first. Thanks for the information ahead of time.
 

Carissa

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Jun 8, 2007
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You want to be able to see all the plants moving around a bit. Flow is important to plants because that's how they get nutrients. If flow is bad, plants will be limited by how fast they can get nutrients from the water column.
 

schwark

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Aug 18, 2008
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Oh, well that is good to know. I might have to look into purchasing a pump or possibly an air stone then. Most of the plants move around a bit, except there is a corner where there is not as much movement... and that might be a good reason why there is a lot of dust like material (flourite substrate probably) sitting on the plants. Thanks again for the help!
 

Gerryd

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Hi,

I know flow relates to oxygen, and I should possibly test for oxygen

Flow is important for other reasons, namely to push nutrients to each plant and to wash away waste products and detritus.

I would NOT advocate the use of an air stone. This will only cause surface ripple which while adding 02, will also drive off c02.

You are better off with either a better/bigger filter, or the use of a small powerhead such as the Koralia nano.
 

Carissa

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Jun 8, 2007
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Airstones are fine for non-co2 tanks that are small (like 20g or less). They help keep co2 levels stable in that type of environment, and provide some extra circulation in a tank with a very small water volume. But in a larger tank, or one that is co2 injected, a powerhead is a better idea.
 

vlvtrope

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Jun 12, 2008
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Flow

I'm really surprised that you do not have exceptional flow with two canister filters. Are you sure you need more current? I have one Magnum 350 and it's like a tropical storm in my aquarium. I have to do things to try to subdue my current. Is there some movement among your plants? If so, I would stick with what you have now.
 

VaughnH

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Our viewpoints about water circulation are in flux right now. Based on the limited measurements Tom made, of CO2 concentrations in various areas of his big tank, we may find that a lot more water circulation is desirable. For now I think it is better to have what appears to be too much than to have what we would have thought would be plenty.

Water circulation doesn't need to mean a huge blast of high velocity water from a small area water outlet. It is better to use something that moves a lot of water, but not at nearly as high a velocity - like a Koralia type powerhead, for example. I have a #2 size Koralia in my 45 gallon tank now, with most of the aquascape in the center of the tank, so the powerhead creates a nice circulation around the center. This has been set up for about 10 days now, and the fish all seem to enjoy it.
 

filipem

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May 21, 2008
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I added a kordila nano today. It's a fantastic powerhead. I no longer have any deadspots around my plants. This powerhead is a far better design for this application then any other one that I was able to find. It's magnetic mounts and adjustable head make this a very easy device to position and hide. Thanks for the recommendation I'm very satisfied with this product.
 

VaughnH

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If I am not mistaken, Powerheads were originally designed for use with undergravel filters. They mounted on the water tubes from those filters to lift the water flow from the filter, which required that they produce enough head pressure or suction to do that, which caused them to be made with centrifugal rotors. Over the years powerheads began to be used for other reasons, but their basic design didn't change. The Koralia type powerheads are unique in using a boat propeller to move water, which gives the high flow rate, but zero head pressure, and low flow velocity that we need for circulating water in the tank. And, the Koralia, in particular, is well engineered with its magnetic mount and swiveling head. I think it is a break through design!
 

keigo

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Sep 1, 2008
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VaughnH;28135 said:
If I am not mistaken, Powerheads were originally designed for use with undergravel filters. They mounted on the water tubes from those filters to lift the water flow from the filter, which required that they produce enough head pressure or suction to do that, which caused them to be made with centrifugal rotors. Over the years powerheads began to be used for other reasons, but their basic design didn't change. The Koralia type powerheads are unique in using a boat propeller to move water, which gives the high flow rate, but zero head pressure, and low flow velocity that we need for circulating water in the tank. And, the Koralia, in particular, is well engineered with its magnetic mount and swiveling head. I think it is a break through design!

Actually the correct name for the Koralia "powerhead" should be wavemaker. This is a very common device which almost everyone in the Marine hobby will be using it.

The better brand wavemaker will be "Tunze" which is far more powerful and better then koralia.

But for planted tank Koralia will be more then enough. Tunze will be more suitable for people with big tank and still want good engery saving wavemaker. :)
 

aquafan

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Sep 5, 2008
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so a small power head or hob empty filter is alright for a natural aquarium for water movement only,wont disturb the co2 or substract?

Randolph
 

jeremy v

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Apr 17, 2008
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Randolph,

In a natural tank (without CO2 being injected) a powerhead is fine. It will increase circulation, and as long as the surface of the water is not being broken and is not rippling from the powerhead, CO2 loss will be minimal if anything.

The empty HOB filter will lose you some CO2 from the water breaking when it falls back into the tank. Remember though, in a non-CO2 injected tank, all a powerhead, air stone, or HOB filter can do is decrease the water CO2 levels to equilibrium with the air, which is about 2-3ppm. They can't drive the CO2 lower than that, because the air will just put it right back into the water, so if plant growth is really slow a HOB filter or powerhead can actually be slightly beneficial by keeping the tank CO2 levels from going all the way to zero by continually pulling small amounts from the air and maintaining equilibrium.

Most people want plants that grow much faster than that really slow rate though, so that's why they want to boost their CO2 in any way possible. The only way your tank can have higher than equilibrium concentrations of CO2 (without injecting CO2) is by trying to hold onto the by-products of fish respiration and bacterial action in the substrate as well as possible. The more fish you have, and the more decomposing matter/bacterial action there is in the tank, the more possibility you have for higher than equilibrium CO2 levels in the tank. That higher than normal concentration of CO2 is what you risk losing with too much surface agitation, nothing more.

Have a good one, Jeremy
 

aquafan

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jeremy v;28585 said:
Randolph,

In a natural tank (without CO2 being injected) a powerhead is fine. It will increase circulation, and as long as the surface of the water is not being broken and is not rippling from the powerhead, CO2 loss will be minimal if anything.

The empty HOB filter will lose you some CO2 from the water breaking when it falls back into the tank. Remember though, in a non-CO2 injected tank, all a powerhead, air stone, or HOB filter can do is decrease the water CO2 levels to equilibrium with the air, which is about 2-3ppm. They can't drive the CO2 lower than that, because the air will just put it right back into the water, so if plant growth is really slow a HOB filter or powerhead can actually be slightly beneficial by keeping the tank CO2 levels from going all the way to zero by continually pulling small amounts from the air and maintaining equilibrium.

Most people want plants that grow much faster than that really slow rate though, so that's why they want to boost their CO2 in any way possible. The only way your tank can have higher than equilibrium concentrations of CO2 (without injecting CO2) is by trying to hold onto the by-products of fish respiration and bacterial action in the substrate as well as possible. The more fish you have, and the more decomposing matter/bacterial action there is in the tank, the more possibility you have for higher than equilibrium CO2 levels in the tank. That higher than normal concentration of CO2 is what you risk losing with too much surface agitation, nothing more.

Have a good one, Jeremy
Hi Jeremy
I read Tom Barr's thread on non co2 non excel aquarium set up, suggested to have some sort of water ciculation for plants without robbing the co2, I was thinking of a small powerhead, thats the reason why I asked.Thank you for your post.
Randolph