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DIY Heater in Canister 11/8/2013
I tried searching your site for this info but only came up with a blank
page. Just my computer or does this happen to everyone?
<Not to me; and I hope not others>
I ask because my computer is over 10 years old and does some weird
things with certain websites.
Alright, what I'd like to do is install a Cobalt Neo Therm 25
watt heater in a Fluval 106 canister filter. I plan to cut the
cord and run it through the side of the canister... So in your opinion,
what's the best way to seal the hole?
<Well; you could get/use a compression coupler... rather than some sort
of grommet... But I wouldn't do this install... too much chance of
trouble if the heater fails somehow, water stops going through the
canister. There are in-line heater holders... I think Lifegard has a
The cord on this particular heater is flat so I don't think a
watertight cord-grip would work. I'm thinking about using either RTV 103
silicone sealant or some sort of epoxy that's safe to use with
saltwater. If you think epoxy is the way to go, could you please
recommend a specific product?
<Either a commercial one as shown, or submersible, hang on the side...
don't do this. Bob Fenner>
Re: DIY Heater in Canister
I've been meaning to plug my power strip into a GFCI for a while now but
never got around to doing it.
Thanks for reminding me. I'm going to order a duplex receptacle this
I've been thinking about all the things that could go wrong with this
install but the only thing that I can think of is that it might leak a
little from where the cord would exit the canister.
<... what if the power goes off to the canister or it's motor fails...
you won't have heat... OR worse, the heater fails, melts the canister;
or cracks the heater's glass... stray electrical potential... real
trouble. Let alone, the voiding of warrantees for the heater and
canister; your insurance company not backing damage stemming from your
That doesn't seem too risky and could be fixed. I don't see all the
potential problems you see - hopefully you can help me to understand.
You mention that if the heater fails there could be trouble. I don't see
any trouble except that I would probably have to replace the heater. And
you mention trouble if water were to stop passing through the canister;
doesn't seem like a big deal other than I might have to clean out the
filter media... or, if it stops passing water due to pump head failure I
might have to replace the head or the entire filter. But there would
still be plenty of water in the canister to keep the heater submerged (I
think) so it (the heater) wouldn't run ''dry''. I constantly monitor my
tank with an in-tank thermometer so I'll know if something is amiss with
One thing I have considered is that due to all the pressure created by
the canister filter, it might break/leak through the seal on the top of
the Neo Therm heater where the temp. control button is but have no idea
how much pressure that seal can handle nor do I have any idea how much
pressure is created in such a small filter. Think I'll have to contact
the manufacturers on these two items. And when you made mention of
Eheim's struggle with producing a resistant heater, were you talking
about pressure resistance?
<... just heater failure period>
Any info you could provide to help me understand why this project is
such a bad idea would certainly be appreciated.