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seeking advise from the more experienced members in our hobby

Seeking advice from our aquaponic community regarding power usage and pump usage


Hi everyone, We live in NW Oregon and the weather is mild this winter, so we are going forward with greenhouse projects, to jump start our growing season.   Currently we have been using goldfish,   in a chop system, letting the system idle down in late November, keeping the water flowing, and then jump starting the system in late February or March depending  freezing temps with a scratch built heater.

Last year I focused on growing tomatoes, cucumbers, peas, beans, salad greens, some herbs, strawberries, asparagus, and celery.    We had a pretty successful garden.   My wife let me replace the greenhouse with a nicer wood and plastic panel structure.  So This fall when we idled down, we  moved  a few rabbits into some of the growing space; and  a small space heater. 

Our system is designed around the pump I selected for the job.  Like a lot of people on here we wanted the moon at first on a shoestring budget, so I opted for using a harbor freight pump.  And it has worked great for its purpose.  But after a brief description of our system I am looking for a few thoughtful ideas on my setup as we expand to raising fish and the associated needs.  

Our system is 1  Ibc tote with top as main grow bed.  Ibc tote has an insulated cover,  I use gravity fed 1.5” pvc  to fill three grow beds with manual valves, and each has a bell siphon feeding into a single 4” pvc sewer pipe.  All collecting in a 55 gallon trash can; in the bottom sits a Hydro star 1600gph pump with a float switch and return 1.5” pvc return line.

   When the pump is activated it does three things.  I have two splitters on main outflow of pump.  Siphoning off some of the water pressure to feed vertical grow towers and pushing some water through 100 feet of 1/2 “ black poly tubing for solar heat in addition to returning water to ibc tote.   The main return pipe from pump has enough pressure to slowly rotate the entire amount of water in the fish tank, which helps with solids collecting in the middle of tank, where I’ve put the intake for the grow bed plumbing.   I also drilled a few holes near the top of the pipe before it goes down to the bottom and it pulls in air which blows out in bubbles to oxygenate the tank and prevents back siphon issues when pump shuts off.

The other end of the poly Solar heater also feeds back into fish tank after it is heated in the tubing.  And excess water from towers drains back to sump.   The solar heater works pretty good when its not frozen outside.  I have a kitchen temp probe jammed into the out flow and it shows real water temp.

For heat I built one of Rob’s designs and used a timer, last winter I had a lot of power outages, and water  losses.  And gave  up on it.   So this year I went with a stock tank heater, on the same timer and will be plugging that in real soon. 

We use 95% rain water to fill our system, and use hydroton for our grow media we Also have T5 grow lights as needed to extend growing.  For power we have been sharing a few plugs from an outside workshop that has a single 20amp circuit breaker with a gfci. 



So here is what I am seeking advisement on


I am unable to run a dedicated power supply back to the greenhouse area for another year.   


So with the current setup I have in place sometimes we pop the circuit breaker at the gfci when both the pump and the heater are on at the same time.  The end result is if not caught within a few hours, the water is drawn down to about 2/3 full in the ibc tote before the airbrake stops the gravity flow out. And I lose the warm water to feed a nearby hedge. Plus have to add more water.  And reheat it. 

First attempt at solution resulted in moving the outflow plumbing higher up the ibc tote side to allow less water to escape when power fails. Which also effects the outflow volume that feeds off of gravity. 

so I may still rework the plumbing in this area, (future upgrade)

second attempt has been to shut off the pump at night, and just heat the tank, till around 11am, So far this has been working.  1 timer for power to pump and one timer for power to heater; Pump during the day, heat at night.    But water temp fluctuates a lot, so still not getting a steady temp in fish tank.


If I were to replace the pump out with say a pond pump that moves 400gph would it  require less power to run, so as not to overload when the heater/ timer  comes on.

 And would I need a larger sump volume to accommodate a pump that was constantly on?

And would it also handle all three tasks of the larger pump or would I need more than one pump to cover my three areas.

If you made it all the way to the end of this ramble,  I would value any input   Look forward to a few ideas from people in similar setups.  This is still in a hobby phase for us.  So keep that in mind.  

I am ready to get the fish fingerlings on order and am just looking for a way to keep power usage manageable, and safe. And not kill off the fish.  I am sure I will find many other ways to kill them as we go along.

Cheers ,

Mark Gordon

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Comment by Pieter Swanevelder on January 29, 2016 at 3:58am

Hi Mark

Glad you could sort out the trip - those (geyser) heater element sure do cause trip once damaged/scaled - finding a crack element not always easy!

Maybe consider adding a phase controller to the heater circuit (i.e. modified light dimmer circuit) - you'll probably will need to swap the triac (of light dimmer circuit) to handle full load - 9A (12A triac i.e. BTA12 or similar  -  should be safe) - - this will allow you to control the maximum wattage (i.e. current) in the circuit - You can then set up the 1000W heater to run at < 500W - freeing up current capacity for your larger pump - i.e. go for slow consistent heating rather than quick fast heating - of course I do not know your operating environment/requirement - i've tried to do some sums to see how long it took the 1000W heater to heat up the water - but it's so fast I decided I need to sleep it off and revisit the model. Do you have any info on water temperature and time heater is on?

some reading matter

Comment by mark gordon on January 28, 2016 at 10:39am

Hello Pieter,

I have been testing the setup again,  I located a different type of pump,  I think its a danner mag , not sure it says model 5 utility and pulls .8 amp at about 465 gph.  so its been running for three days, I am going to keep my other pump setup as a backup for when I need to add water,  this little pump will do the job  for now.  My heater was causing the fault,  I discovered that the element has cracked in turn caused the gfic to pop.  So its been pulled out and I am going to order a new element next week.  and rebuild it again.   As far as I could tell the gfci would trip after the pump kicked on, when the heater was already in use.  the lights have been off, so no indication of a flicker.  

I want to thank you for the help  as I looked up and learned about the power usage. I  can tell there is a lot more to learn.

 So far I have been able to answer a few questions;

 1. my sump is about 48 gallons and I will be replacing it with a different design probably a bout 75-100 gallon Rubbermaid water trough.  this will give the little pump more capacity, and I could probably move my goldfish into it.  

2.  Fingerling fish will be ordered next week and I will house them inside my house in a real aquarium while I work on greenhouse power/ heat project. I have had an aquarium for over twenty years, so this will be the easy part.

3.  our Vertical towers will be put on hold this year.  I had 5 setup and they worked okay, but will be focusing on the main grow beds and we can always expand later on again.

4.  Solar heater also can wait.  I was using 100ft of black poly1/2 tubing, coiled up on my nearby workshop roof

and as water was pumped through it was warmer by about three degrees,  But with the little pump it barely can keep up just moving the sump water. 

5.  I have replaced the power line with new 10 gauge power cord. its only 15 ft long. 

Thanks again.  I will be in touch.  and will post some new photo's soon


Comment by Pieter Swanevelder on January 25, 2016 at 4:11am

Hi Mark -

Thanks for the info - first - typical disclaimer re expertise. Note that I'm not living in America - so I'm possibly not knowledgeable regarding American/state wiring practice/code.

Pump - I could not find much info on the type of motor in the pump-set (i.e PowerFactor?) - but typical these size pumps are single phase induction motors (I've seen a "start up"  capacitor in one of the maintenance manuals) )- you can expect a start-up current of 5x to 6x rated current.  Thus ensure that your Circuit Breaker is rated at the correct curve  - typical a C or D-curve - you can find a summary here:  (refer instantaneous tripping current)

Do you experience the trip during start up of the pump - or when pump and heaters are working for a while?

Power Cord - We have 1,5mm Cu dia as nearest to 16AWG - for 15A @ 25ft give a voltage drop larger than 5% - consider a Power Cord with 4mm Cu dia (6AWG) - if the line voltage drop is to large - this will result in pump to draw more current as it tries to speed up.  Also the 15 Amp is very near the rated current of the power cord - this will result in heating of your cord with increase in resistance, drop in voltage, etc..

Maybe consider adding a circuit breaker rated for each circuit - i.e. D6 for pump, D10 for combined heaters.

Sump - i've got a similar set-up as you (sans solar panel and VT (in work)) - I've sized my sump for 60% Grow Bed volume  (3x 1.1x0.9x0.3m^3) + spare -> ended up with 1m^3 as I've got the capacity available. Probably will need to add once I've added my VT's. i.e.sump need to be able to take volume of VT's + GB + spare ( I also got a few fish in my sump to take care of mosquitoes)

Solar Panels: i've noted on my swimming pool passive heating solar panel that they're very susceptible to wind (convection loss) - if the wind blow over it - they act like heat radiators! these are the low heat panels (<65degC) - open to air - what type of panel do you use? how do you control heat flow?  I was thinking of similar panal - but with additional transparent cover to isolate from wind.


From Aberdare cable cataloque (low voltage)

type AWG Metric Current rating Volt Drop Distance Load Current VoltDrop
mm A mV/A/m ft m A V
16 1.29
15 1.45
1,5 17 29.00 25 8.33 15.80 7.64
surfix 6 4 30 11 25 8.33 15.8 2.90
cabtyre 1.5 16 32 25 8.33 15.8 8.43
cabtyre 4 32 12 25 8.33 15.8 3.16
AWG-Metric conversion
Cable data
Pump Radiant Heater Tank heater Lights total
Power 660 300 1000 W
Supply Voltage 120 120 120 V
Power Factor 0.7 1 1 PF
7.86 2.5 8.33 18.69 A
Start Up factor 5 1 1
Start up current 39.2857142857 2.5 8.33
Comment by mark gordon on January 22, 2016 at 12:46am

Power extension cord is 25ft, it's probably 16 gauge.  No markings on it,  Its probably over ten years old. I remember I chose it because it would fit under the shop door when I closed it.  

power meter is 119.8 +/_.2 at the plug in workshop.  Power in greenhouse is 120.6 +/_ .2 volts.  I think the wire on the heater is 12 gauge.    I rebuilt it about two months ago.  Last spring I was running it on a separate line directly to the gfci plug.  After I rebuilt it,I shortened the wire, and just plugged into the same line as the pump.  After work tomorrow I'll test it with the pump again and give you the numbers.  

As I start looking all the changes since I first started down this path.  I need to find time to become an electrician.

I appreciate the help

Comment by Pieter Swanevelder on January 19, 2016 at 7:20pm

Thanks Mark

Please advise length of feeder cable (from main db to greenhouse) as well as wire gauge AWG/copper diameter - this is to determine the voltage drop in your feeder cable.

Does the power trip when you start the pump and heater is on or vise versa?

If possible - please measure the line voltage at your greenhouse db. 1) pump & heaters are running 2) nothing is running. 3) during pump/heater start-up - (if your lights dim during start-up of either - please note.)


Comment by mark gordon on January 19, 2016 at 2:07pm

Hi Peter,

I found a power calculator online and ran the math.  

Power useage for greenhouse   


Single 110 power outlet on a 20amp breaker shared with my workshop


Hydro star 1 HP Stainless Steel Submersible Dirty Water Pump with Tethered Float 2910 GPH

Ac 120 volts  draws 5.5amps under load  calculator = (660 watts)


Heater ( currently  using )  am open to other options

Allied precision submersible tank heater 1000 watt 120volt  


 Radiant Space heater 300 watt,  only use when temp at night drop below freezing, as we are housing our meat rabbits in greenhouse over the winter.   So it is on on a quarter setting so probably 200 watts an hour for the last month.  Also keeps whole greenhouse above 45* and keeps the moisture off the walls and ceiling.  

we have it on a time for about 14 hours a day at this point. 


I have a few different timers most of them are 24hour settable.

Pump                   660 watt

Radiant heater      300 watt

Tank heater          1000watt 

Total with internet calculator says I am pulling 15.8 amps

So I guess I need to either not heat my workshop space, or locate another circuit that I can attach my heater  power supply to. or down size my pump  or both


Is it safe to use a heavy duty power cord and run it say about 50ft, and still pull 1000 watts through the line or Should I bury it in some conduit ?

Comment by Pieter Swanevelder on January 19, 2016 at 5:04am

Hi Mark

Just confirm the pumps power (see HydroStar 1600gph ~ 0.5Hp)

What is the power output of your heater element?

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