# heater under sand?



## sasquatch-exists (Feb 25, 2009)

can you put a fully submersible heater under a thin layer of sand?


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## ben1988 (May 2, 2009)

i am pretty sure nothing is suppose to touch the glass of the heater at all...


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## 810Aaron (Apr 19, 2009)

I use 2 200watt Stealth heaters in a 120 gal tank and they are both buried under a half inch to three-quarters of an inch of sand, I don't seem to have any problems.


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## Mikey13 (Apr 1, 2008)

I don't think that it would be dangerous to do that at all, but the physics of it is pretty simple.......a buried heater will be almost worthless to the rest of the tank. Would you skip ductwork in a home and just pipe warm air a foot under the earth and hope it warmed the entire house? In floor heating might be fooling someone into thinking that this will work in an aquarium but the 2 scenarios are quite different. With no water moving across the heaters surface, i would take a wild guess that you are wasting 70% of the potential heat output you have just to hide it. Just my .02 worth.


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## sasquatch-exists (Feb 25, 2009)

I thought that the energy would be transferred/absorbed by the sand primarily....But I'm no chim major so....


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## BurgerKing (Jul 1, 2008)

I'm with Mikey13. If you're trying to hide the heaters then just place them close to the sand surface where they get some decent water movement. I've seen people bury heaters in nano tanks without any negative side effects, but I consider that a completely different scenario.


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## Toby_H (Apr 15, 2005)

I've only used Visi Therm Stealth heaters for a number of years which have a plastic exterior as opposed to glass... so my comments are based on experience with them... experience with glass submersible heaters may vary...

These heaters can be buried and they still work... but they are less efficient...

The sand acts as a 'buffer' between the water and the heater... thus if the water experiences a change in temp (for example: water change, direct sunlight, AC vent blowing directly on tank kicking on for first time that day, etc) it will take longer for the heaters thermostat to acknowledge/receive the change.

Therefore the heater may not kick on as fast or turn off as soon as it would when in uninterrupted water contact...

A buried heater will transfer energy/heat to the and the sand will carry it to the water. This also decreases efficiency as when the heater turns off (already delayed) the sand will still be warm and will continue to heat up the surrounding water. Likewise when the heater first turns on (already delayed) it will take some time to heat the sand to a temperature that can then heat the surrounding water...

When burying heaters I have not noticed any major temp swings, but in my experience tanks with buried heaters have a much less stable temperature. For reference I have stopped burying heaters in sand due to the above experience...

Instead I simply place them behind decor in an area with higher current. I often use powerheads to prevent waste/debris from collecting in/under/behind decor. So I hide both the powerhead and the heater behind the decor...


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## noddy (Nov 20, 2006)

The only way to bury a heater under a thin layer of sand, would be to bury a thin heater. I personally don't know of any.


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## cichlidsandmore (Jul 14, 2009)

I'd contact the specific manufactuer to make the best and safest call.

I've heard some heaters are designed to only be installed upright. Not to ring alarms, but a good aquarium guy said he's seen some burst being laid on their side.

With overflow systems, he recommended placing them upright and deep in the external section of the overflows. The warmer water comes directly out of the jets and distributes through the tank quicker and more uniformly.

The deep, external overflow position also keeps the heaters submerged during water changes to help prevent damage to the heaters glass tubes from rapid temperature extremes.

Placing the bottom end of the heater tube in a small piece of hot water grade PVC can keep the bottom of the heater tube lined up and the hot glass tube off the overflow plastic.


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## frank1rizzo (Mar 14, 2005)

They will heat up the sand and turn off because they have reached the desired temp. Meanwhile the rest of the tank may be 5 degrees colder then you wanted. You need to have water flowing past the heaters for them to work. There is little to no water movement under the sand.

I would not recommend it.


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## madjecks (Jun 8, 2009)

Mikey13 said:


> I don't think that it would be dangerous to do that at all, but the physics of it is pretty simple.......a buried heater will be almost worthless to the rest of the tank. Would you skip ductwork in a home and just pipe warm air a foot under the earth and hope it warmed the entire house? In floor heating might be fooling someone into thinking that this will work in an aquarium but the 2 scenarios are quite different. With no water moving across the heaters surface, i would take a wild guess that you are wasting 70% of the potential heat output you have just to hide it. Just my .02 worth.


just wondering how you can compare a x gallon tank to a house with piping underground. This sounds pretty much like a furnace heater concept in a home.The Heater is under the gravel, the heat rises and circulates via the filters/power head/whatever, but I hardly think you would lost 70%, I'm sure with proper water circulation you probably wouldn't see any loss at all. I'd not use glass heaters :lol:


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## madjecks (Jun 8, 2009)

frank1rizzo said:


> They will heat up the sand and turn off because they have reached the desired temp. Meanwhile the rest of the tank may be 5 degrees colder then you wanted. You need to have water flowing past the heaters for them to work. There is little to no water movement under the sand.
> 
> I would not recommend it.


This however is a better argument! But I still think with good water movement You won't see much of a difference.


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## frank1rizzo (Mar 14, 2005)

Even with good water movement, your not moving the water around the heater. If you had the thermostat for the heater switch in the tank, then it would work, but since the switch is located on the heater itself, it will shut itself off.


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## Toby_H (Apr 15, 2005)

essentially... the sand acts as an insulator...

Therefore the heater will turn on and start heating the sand... as the sand retains heat the heater will reach it's preset temperature and turn off... just because the sand surrounding the heater is XX*F does not mean the water flowing in the tank is that temperature...

So burying a heater is unlikely to damage the heater... but will result in less temperature stability and will loose some efficiency... It is arguable how much efficiency is lost, but the big downside in my opinion is the loss in stability...


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## Mikey13 (Apr 1, 2008)

When i made the statement about trying to heat a house with plumbing from below it, i was only trying to show the inefficiencey of the set up as an example. As it has been said here by someone else, the sand doesn't allow an EFFICIENT transfer of heat from the heater to the rest of the aquarium. I'm not saying it won't add any heat to the water.......just that it's not at all efficient. What i meant by the 70 % part was that you might be losing that amount of POTENTIAL heat energy getting into the water instead of possibly having premature shutoffs or starts, which aren't using the heaters full capabilities.
If you want to keep looking at it in relation to a house....picture using your current furnace, but let's say you told the builder to just run ducts in the cement slab of the basement. The amount of heat you are able to generate is the same...just delivered differently. Your basement might have a warm floor, but your upstairs bedroom is going to be pretty chilly even if you had a fan blowing from your basement(much like a power head in the tank). Compare this to a duct system that uses delivery and return flow in every room, with the same generated heat, and this dispersion(like a non-submersed heater near a powerhead) is vastly more efficient and uniform through the entire house. 
I suppose to beat a dead horse.......under sand takes away any direct radiation of heat via water movement which was how it was designed to be used. If i had a 90 gallon tank with no water movement and a strong heater in one absolute corner....i bet there will be a significant cold spot in the other.

Bottom line....if your set up works and you're happy, then keep rockin' that. I wasn't trying to judge or change the way anyone runs there stuff, i was just trying to explain what i had said to you a bit better. In my opinion...the fact wether it's glass or plastic isn't really the issue here. It's wether it's the smartest move or not.

Take care....


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