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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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Okay, looks sloppy now as pulling back electrical tape did a number. If you look closely there are three wires (black, white and green). I wired the white one where you see the white letter "N".

If you see a problem, let me know. Also, let me know about peeling back glued gasket under nut and placing ground there.... I was just worried that if I slice open a space for the ground that I may compromise the seal?

Thanks Steve!
Never thought of that, but I'll wait until you comment on photo and grounding issue.

StevedNETN said:

if you plug heater directly into wall, you could watch and see if it heats.  Test heater vs controls 

Looks right to me.  I would twist wires more so they stay under screw better.  Would try plugging directly into plug.  Ground looks fine

K. Thanks Steve. Too tired tonight, so I'll leave for the morning and report back.

... Wish I had some vodka and orange juice!

Later -

9:am this morning I cleaned up wiring on element contacts as advised and bypassed temperature controller and plugged element directly into wall outlet. Water temperature at 9:am this morning was 18.7 C (65.66 F) and at 4:30 this afternoon is now reading 18.9 C (66.02 F).

For what it's worth, I also took my little electrical "pen" current tester and touched each contact on element to see if cord wires are live... Both terminals lite up with no issue.

I was hoping for a faster heat up on 1200 gallons using a 1500 watt element, with an ambient air temperature of 20 C (68 F), but maybe this is going to be a slower process than anticipated?

What do you think... Should it be heating faster?

Also, if temperature eventually climbs significantly, I'll plug back to controller to see what happens?
Sounds a bit slow, but let's watch it over a few days
K. Patience is a virtue... Lol

Have a good one!

Seems to be heating a bit slow.

You need to look for where you're loosing heat/energy

- check voltage over (v) (voltmeter require) & current (I) through (ammeter) heater element.

--- check terminals are properly fastened - loose terminals = volt drop

--- check supply cable thickness.

- check insolation of FT - radiative/convection/conduction heat loss i.e. what else are you also heating

- check insolation of basement - keep heat in room?

Lossless model;

System Volume Litre 1204 Gal 4550.0 4550.0
Temperature Setpoint °C 18.9 25.0
Temperature Startingpoint °C 18.7 15.0
Heater W 1500.0 1500.0
mass to be heated kg m 4550.0 4550.0
water heat capacity J/kg.K c 4200.0 4200.0
Start Temperature °C Ts 18.7 15.0
Target temperature °C Tt 18.9 25.0
temperature difference K dT dT=Tt-Ts 0.2 10.0
Heater Energy kJ Q_heater Q=m.c.dT 3822.0 191100.0
Heater Power kW P_heater 1.5 1.5
Time to temp s t=Q/P_heater 2548.0 127400.0
hr t[s]/3600[s/hr] 0.7 35.4
Good morning Steve,

Thanks for the chart, it's similar to the few I was using.

Temperature overnight increased very little, so that got me thinking... The power wire from element is an old wire I chopped off from a very old small wine fridge. I checked out its gage this morning (via the net) and to me it looks like 16 light duty gage (I had to twist threads together). Maybe I should be using 14 gauge instead, to carry the full load more efficiently. Just guessing at this point, but you did mention it so maybe we're on to something?

No worries about the room temperature. When probe is removed from water it climbs rapidly to catch up to ambient air which is always between 68 and 70 degrees F depending on what the weather is doing outside. Probe controller box is mounted against my coldest outer wall, so that's worst case scenario when testing air.

I'll pick up a 14 gage heavy duty extension cord this afternoon while out and swap out and see where we go from there? Thanks for going that extra mile with chart.

I'll keep you posted.

Hi Chris,  
Peter actually put that info together for you.

A meter is truly the best way to test this, but one sure fire sign that your wire is too small is it will be warm/hot.

If there is any heat from the wire, it needs to be bigger.  

I have a system that I believe holds about 900 gallons of water and i put a 1000 watt heater inline.  I achieved about .5 deg temp rise.  But this was at neutral external temp, so little to no heat loss.  You may need to have a larger element.

With the rig you have set up, you could easily increase the element size. How far away is a 220 volt plug (Dryer?  or breaker box?)

... Just noticed your post was posted at 2:37am! .... Hope you're not losing sleep over this - lol.

Another thought would be a second heating element.  You could add another SSR just like what you have and another element and run a quality (12 gauge) Extension cord to the next nearest plug that is on another breaker.  This could double your heating capacity for fairly little effort.  Do you have a second port in your filter like you installed the first element in?

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