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By: [ Editor ] Asked from United States of America

Having some problems heating tank...

So, after 1 waterbed heater would only get my water temp up to ~84 degrees F on its own, I tore my tank all back apart, pulled up the liner, and put TWO more waterbed heaters underneath it. I did not expect any further problems but so far it isn’t looking good even with all that extra heating power. I have all three heaters cranking and currently I’m at 92 degrees F. (This is plain water, test phase still.) Tank is 8x6x6'. I also have not cut ventilation in yet and am wondering how much that will also work against my heating.

Anyone have any insight as to how much better the water will heat with salt in the tank? I have the salt finally but I’m being a chicken about throwing it in because I currently have no way to reclaim it and don’t want to see end up down the drain.

I guess worst case scenario is that I have to add an external inline heater?

Thanks!

-Don

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terrence brannon [ Moderator ]

Anyone have any insight as to how much better the water will heat with salt in the tank?

I think it will heat worse. It is harder to heat salt water than plain water.

I guess worst case scenario is that I have to add an external inline heater?

My tank dimensions are the same as yours in terms of length and width. But I’m only 32 inches high total. How cold is the room. And is there 2 inches of fiberglass insulation below the tank as most heat escapes out the bottom.

But yes, JBJ aquarium heaters are hot I do the passive heating for my tank WITH epsom salt and no problems. I turn off electricity while I float and get 2 hours easy.

NN comments
dcorsmeier
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Actually, every reference I’ve found says the heat capacity of salt water is less than fresh. This means, degree for degree, salt water is easier (takes less energy) to heat than fresh. Therefore it heats faster. Unfortunately, the best explanation I can find is: http://www.swri.org/10light/water.htm

Haven’t had time to consult a chemistry book (or chemistry person).

terrence brannon
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@dcorsmeier Yeah I read on Specific Heat and Specific Heat Capacity here: http://www.iun.edu/~cpanhd/C101webnotes/matter-and-energy/specificheat.html

and it’s in agreement with what you said – it takes less energy to heat salt water than plain water.

But: (1) I know from experience, that I’ve had a plain water tank with 10 ins of water at about 93.0F and the second I drop in salt, the temperature plummets (maybe the salt itself was cold?) (2) the more granular the salt, the faster it dissolves. If you just dump salt into a waterbed situation like yours, the waterbed heaters have been known to go into overdrive and melt the bottom of fiberglass tanks… just ask Tim Strudwick. (3) maybe our calculations need to take into effect the heat required to create salt water. That is, while the SHC of salt water iself may be lower, the heat required to create salt water may be higher. The Deep Self recommends dissolving epsom salt into water heated to 130F. I often would turn on the tap to full hot and watch that salt dissolve like a hot knife through butter.

So once you get salt water, maybe it’s all downhill there. Why dont you ask here: http://groups.google.com/group/sci.chem/topics

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