Evenly heating a filterless nano cube. - The Planted Tank Forum
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post #1 of 6 (permalink) Old 07-30-2018, 01:24 AM Thread Starter
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Evenly heating a filterless nano cube.

I've just set up a filterless, low-tech, Walstad, 4 gallon (10") cube, with some hornwood, and various low-light plants.

I put in a 25-watt Cobalt Aquatics Neo-Therm heater, in the rear corner, but without a filter, it's not heating the water evenly.

Near the heater, it's 78 F. But, just 3" away from the heater, it dips down to 74 F.

Any suggestions? Maybe I can run 2 x 5-watt heaters, on opposite sides of the tank?
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post #2 of 6 (permalink) Old 07-31-2018, 09:11 PM
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If you have no circulation, you will always end up with hot spots by the heaters and cooler areas the farther you move away.

You will get some Brownian Motion from the excited warmer water by the heaters, but not enough to evenly heat the water column.

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post #3 of 6 (permalink) Old 07-31-2018, 09:30 PM
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Sounds somewhat normal when nothing is used to move the water. Maybe a sponge filter or small pump to move a tiny amount of water, even if there are no fish to wonder about the gas exchange? Bubbles from an airstone do move water as they rise--- but the pump is also noisy for many!
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post #4 of 6 (permalink) Old 07-31-2018, 10:10 PM
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maybe sit the tank on a stand with a cut out in the center for the heater to be
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post #5 of 6 (permalink) Old 08-01-2018, 03:13 AM Thread Starter
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Glad to know this is basically normal for a filterless tank.

Interesting idea about placing the heater in the middle of the tank. Not sure how I'd run the heater's wire though, but definitely an interesting idea.

I may end up running a tiny air stone at some point, but if I can avoid it, that would be better, as it's currently 100% silent, which I really really like.

Thanks folks.
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post #6 of 6 (permalink) Old 08-01-2018, 04:23 AM
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Depending on the room temperature and lifestock, you might not even need a heater.

Or you might be able to find under-the-gravel heating cable or use a CFL bulb in a dome light.
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