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URGENT - Please Help with Electrical Inline Water Heater with Temperature Controller

Hi everyone!

I am a koi hobbyist living in Montreal, Canada. I have an 8000 gallon outdoor pond in which I have 24 koi, ranging in size from 12" to 24". I could or should I say "should" leave them outside for the winter, but I've opted to bring them inside now for many years. I used to have 3000 gallons in my basement winter set up, split between two tanks. One, which was a 1700 gallon above ground pool developed several leaks over the years, so I trashed it last summer leaving me with the one tank, a 1200 gallon capacity. Needless to say, this year fish are very stressed due to being overcrowded. I could give you plenty of more details as to how I care for them,may need for a hospital tank, but I'd rather get straight to my question. :)

Two fish have developed two small ulcers which I am currently treating, but I need to raise the water temperature from its current 60 degrees F to 76-77 degrees F.

I'm on a restricted budget (unemployed), so I am not in the position to purchase an expensive inline spa water heater or anything else in the same price range.

I've attached a couple of videos of DIY inline heaters, easy to make for under $100., but need to know what supplies I would need to change up if going with a higher watt system. I would like to use either a 1500 or possibly 2000 watt element. I'm assuming that the first video below is a 1000 watt or less, because nowhere is wattaged mentioned (unless I missed it). Second video is well under 1000 watts.

So if any of you have experience with these type of DIY devices, kindly advise the correct parts required, meaning: element, size of thermostat controller and If I need a solid state relay? The relay part has me confused as I have never used one in any electrical application. Remember, this is for a 110 outlet, which already has a 1/4 horsepower pump and a hefty air pump plugged in to. What amps should I have on this circuit? (maybe I need to call a licensed electrician to increase amps at my electrical box?)

So here are the a couple links for the general idea.
Please answer ASAP as my two sick fish need more warmth in order to heal.


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All three together fo easy reference.

The palm pilot power supply would do just fine.  

Thanks Steve!!!

Will it work with my ssr that's already ordered? Or do I need to get something else. Here is the link to the ssr that's enroute to me right now.

Also, I telephoned two of Montreal's largest plumbing heating supply stores, and they told me that stainless or incoloy elements are few and far between in Canada, so looks like I'll be driving to New York State on Saturday - that's if all my Canadian inquiry emails come back negative.

Let me know about the ssr, and when my parts stat arriving I'll start some of the assembly... Hopefully I won't hound you or others too much.


Yes, that will work with what you ordered.  


Hi Chris - glad you get sorted.

Just note -  2 of the 3 power supplies you shown is DC 5V - should be fine as the relay works from 3 to 32Vdc.  If you look at Steve's drawing - follow the positive (+) terminal from the walmart/PSU - through the HEATER on the controller to the SSR - mark this as (+) and this terminal relates to the (+/terminal 3) on the SSR. If you get the polarity wrong you could damage the SSR.  One of the PSU's show the terminal polarities as well.

I don't have a controller manual - but don't set the control hysteresis to small - your controller will then activate the SSR frequently to keep the temperature in a tight band. - Each time the SSR switch there is a power component over the contacts and the SSR starts to heat up. So try to mount it on a flat piece of metal - copper/allu/steel to dissipate heat (just don't use your nearest's pots/pans - that's lethal) using heat compound/-washers in between - if available. Also 110Vac is dangerous - so try to keep all open connections covered/insolated.

You don't say what your air pumps current or power consumption is?

Good luck!

Thanks Pieter,

I've been dealing with my sick fish most of the day. Would you or Steve put your stamp of approval on the following element, keeping in mind that I need stainless steel or incoloy for fish.

As I read it, it appears to be stainless steel?


That should be great


Water Pump is large with metal casing. It came pre wired from factory. So are you telling me that since the pump is already grounded that the ground wire from controller box's power cord doesn't need to be grounded to anything? I'm a bit confused... How can a separate appliance, in this case the pump, ground and protect the controller box?... They're separate devices that are wired sepeartley? Please explain

I received my ssr yesterday and the backside of ssr is totally metal... Does this need to be grounded somehow? I was planning on using a PVC OR PLASTIC project box to hold temperature controller and ssr (see ssr photo) and if I understand this installation correctly, the only wiring coming OUT of the project box will be 3 things: controller power plug, wall wart plug and the sensor? Is this correct?

Pleas clarify the grounding of controller (heating element) I don't want to toast any fish.

Thanks to your help to both you and Pieter!

StevedNETN said:

Hi Chris,

You are more than welcome.

The item the youtube build recommends is a contactor.  Similar in many ways to what you have purchased.  No worry with what you have purchased. 

Since you have a wooden tank, I would recommend just ensuring that your recirculating pump is correctly grounded.  It likely has a fairly substantial metal housing, will be used all the time and should have a ground already.  This will suffice.

A "Wall Wart" is a slang term for the little black box that you plug into the wall to power little electronics. It is an AC to DC transformer.  Most people have them laying around from misc broken things.  for example an old toy, rechargable battery or tool, old laptop computer power cord/supply.  Basicly you need a way to get a DC current to run the SSR you purchased. Google "Wall Wart" and you will see what I mean.  

I have read that Stainless elements are best, but with difficulty finding what you need, I don't know if they are really essential.  The standard element would work just fine, I am not sure if there would be some risk to the fish?? May be worth further research there.  Personally, I would purchase the same item used and stocked for water heater.

They are zinc coated and have copper elements.  $11 us. 

You may reach out directly with one of the moderators on this site to ask if they can give you a straight up answer (Based on fact not theory) on if there is any risk in using one element vs another. 

Pentair is a supplier in FL that carries products for commercial aquaponics and aquariums.  They sell replacement elements for systems they sell for this purpose and they are Copper / Nickle elements.  Same as what your local hardware store sells you for your electric water heater.

Also, what gage of wiring should I be purchasing for this job? I'm using a cut off powerbar cord for the controller box plug but not sure what size of wiring I should purchase for the rest?

And how should I cover (insulate) the contact leads from the heating element coming out of my filter tank? Do they sell anything to cap this off or should I just cut a PVC conduit pipe to put over leads and fill with silicone?
Hi Chris, 12 gauge wire should be good for the heater. If the wires on the element are exposed, you could create some type of cover so you can get to them later. I think I would wrap with electrical tape and the put a plastic cover over them too. Be creative :). We're you able to get all your parts?

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