tank circulation

[shamrock]

just wanted your expert opinions on the hydor koralia series for tank circulation. i understand it's used in marine tanks. it has very good output, the only disadvantage i can foresee is aeration and some trouble attaching it to the end of a filter?

thanks

[FuglyDragon]

I use them, good even flow. Moving the water around increases oxygenation. They are pretty much stand alone though, dont need to be attached to filter outflo. Only problem i have had is you have to be very careful not to break the ceramic shaft while cleaning them. Very strong magnetic mounting system, way better than the usual suction cup approach

[MatsP]

The koralia series of circulation pumps are indeed very nice.

I'm not sure what problem with attaching it to the output of a filter would be - if I had one, I'd just hang it somewhere to make the flow of water better - filtration system is a separate unit, not something you connect a Koralia pump to.

Aeration is probably not an issue either - the real benefit of pumping air into the tank is twofold:
1. It circulates water up/down in the tank, causing more even distribution of oxygen in the water. The amount of oxygen taken up by the water is much better at the surface of the tank than the small bubbles that occur in the water when you add an air-stone - but the airstone makes more water come into contact with the surface air, so there is a good benefit there.

2. In a tank with a closed lid, it forces fresh air into the tank.
This allows new oxygen-rich air to enter the system, and the air with more carbondioxide to be expelled from the tank.

As FuglyDragon says, moving the water in general will help the level of oxygen in the tank.

--
Mats

[shamrock]

thank you.

while we're on the subject - how do these compare to the eheim circulation pumps? they're about the same price, but koralia has incredible output in comparison? the only disadvantage(?) is the fact that you cannot add a diffuser.

thanks

[MatsP]

I'd go for the Koralia. I have a two Eheim Compact (and about 5 with a similar concept from Hydor), but at present, I think the Koralia pumps are a better choice. Just make sure you don't get one that is TOO big... You want a total turnover rate in a tank that is about 10-30x, if you are keeping plecos and such.

--
Mats

[shamrock]

great. thanks a lot. definitely going to consider the koralia. for my next tank set-up.

[FuglyDragon]

I have both as well and find the Eheim compacts tend to clog up much quicker than the koralia and require more frequent cleaning (usually weekly) to unclog the intake. Also they produce a totally different type of current, the eheim is a direct jet the koralia is a more diffused cone type effect.

[bronzefry]

I use 1 Hydor Korelia Nano on a

Chaetostoma milesi

tank, 20 gallon long. I found out who the alpha male was very quickly. The only time he comes down is when I do a water change. I need to unplug it.
Amanda

[andywoolloo]

I have koralias in two of my tanks, with pl*cos. One is the older one and on is the newer one. I have always been very pleased with them both.

[shamrock]

great. they do sound reliable and easy to maintain. (or easier rather). what about diffuser? i guess that's out given it's shape. just thinking of how Haavard Stoere has set up his circulation pumps (incredible tanks btw), he's made some sort of a housing underneath and put a few filter pads. i think MatsP has already answered the diffuser part by suggesting it's circulation rather than bubbles? correct?

thanks again

[2wheelsx2]

I don't use my powerheads for the diffusion function, as least not the way people traditionally use them. I run Koralias near the surface of the water and have then ripple the water surface for contact turnover during lights on. After lights out, I have a Aquaclear with a venturi to enhance the gas exchange because my tanks are planted. This serves 2 purposes. I hate looking at bubbles in the water (my plants pearl like crazy already) and also allows me to have less noise (no bubbling) during lights on, but more air during lights out.