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DIY submersible water heater, build your own water heater

***Be sure to use a GFI plug with this!***

here is a link to the Through-Wall version

 COPPER WARNING! most of the elements are made from nickel plated copper and should not be used!

I have not found stainless elements at Home Depot. Some of the Lowes stores have them.

A quick search on the web will find several types in the 240volt range.

Some links to try:

 1500 watt in the 120 volts stainless steel unit.


 here are some stainless steel options. they only make them in 4000 watt+ at 240 volts.


I've made a few changes to the heater parts list and instructions..


1500-5500 watt stainless element

12 awg cord

1-1/2" rubber coupling

1-1/2" reduced to 1" threaded

1-1/2" reduced to 1/2" threaded

1/2" water tight connector


Temp controller
















install the element into the 1-1/2" - 1" reducer.

...these are made to be inserted in one direction, so you will need to use a grinding wheel, or improvise, to remove the "stop" portion of the fitting.

some are sold with a round edge (pictured here) and some are squared (pictured above)

after removing the stop, connect the wires and install into the rubber coupler.





Here are a couple different

submersible options.

the top one has the wire ran inside the 1/2" irrigation "funny pipe" and fittings.

both work great!










I have used a heavy duty timer to control the temp. 15 mins on the hour will keep 300 gallons warm.

pex supply has thermostats

Use a GFI plug with this unit!





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I have a question for you, Rob

(or any other electrical wizards)-

Suppose I have a 240V element and a 120V power supply.

Does this simply halve the effective wattage?

Here is where my question comes from:

I found some rather brilliant submersible aquarium heaters on ebay.

(the tube is stainless steel rather than glass, and they are really tough!)

They are 300W, with US- style 110V plugs,

but they are labeled 240V.

I contacted the seller, who confirmed that they are 240V heaters.

They appear to work just fine,

but I'm assuming they are producing 150W pf heat.

Am I correct?

Alex and Vlad know more about it than i. but its my understanding that it uses 1/4th the amps.

close shas, you thinking is correct except when dealing with heaters as they are essentially huge resistors. I made that mistake as well... If your heater is designed for 300w at 240v (volts^2/watts=resistance)then your resistance will be 192ohms (this value does not change)@1.25A hooking this up to 120v then (v^2/R=w)=75watts @.625A I had plugged all  this info into my ohms law formulas early on without thinking of the fixed resistance value and it through me all off.I'm working on a dc version of this for my outdoor setup,its significantly safer and offers redundancies for blackouts.

Rob, you have shown us both Camco and Richmond brands

120V ss water heater elements.

I hate to be a pain, but I'm having no luck finding them here in Canada.

Could you please post the parts numbers for these?

Many thanks.

Thanks for the education, Alex.

That explains why these heaters are a bit slow to heat my near-freezing creek water.

Shas, this is the only place i have been able to find a 120v

Dang sweet this is Bass Add! Thanks for sharing, I am noticing that us AP folks are also inventors and mad scientist!! Good stuff, 

I've got my 300gal. tank buried in the ground. Do you think I will have trouble with low temps in the winter? A guy at TX Hydro sold me a 300W heater but the package says it is only rated for a 70gal.....Not sure I should of bought it but the guy has been very helpful in the initial stages of my system.

...ask him if you can get a store credit for it. with your tank in the ground you wont have to run it as much. this heater will boil your 300 gallons if you dont keep it controlled. ...get the thermo/controller, it makes everything better ...ive been very pleased with the 4 i use.

BIG NOTE *** USE THE STAINLESS ELEMENTS, AND A GFI PLUG! ***   ...i feel obligated to remind everyone about this.

Hey Rob,

What is the issue of using copper? Will it contaminate the water?


Hi, can this be used in a saltwater tank? Will the stainless steel heating element corrode?

i have found that Lowes stocks Stainless Steel elements... they are all 220 volt at 3500 - 5500 watt. these can still be used with 120 volt connection. this will drop the wattage down to 1/4th...  the 3500 will run at 875 wich is good for about 150 gallons, and the 5500 watt unit will run at 1375, which will heat 300 gallons. if you really want to get the most out of the heater, go with the 240 volt wiring and the Ranco temp controller from Pex

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