Backyard Aquaponics
A place to discuss aquaponics

it was 180 watts your right. I bought one at my discount from my plumbing supplier and got it for $171. However when i was driving home i noticed on the box that it said it had a oil bath for the bearing . So i turned around and took it back for a refund. I remember reading a post to beware of oil filled models because of possible fish kills. So went to look at a grunfos pump of the same specs and they wanted $380 .. which i thought was a rip off. So now im trying to source a ebara optima as a few people have them and they come recommended. the max head height i need would be 4 mtrs.
peace and subwoofers
Pete

i rang ebara and a salesperson informed me that the optima indeed has an oil bath on the seal but he said it was food grade oil. What difference would food grade oil make? I priced a couple of other pumps a grundfos kp150 submersible $384.30 and a davey dyna 8000 @ $341.28 any one had any experience with these? They both sound a little excy.

I think any oil would probably be bad

Get one of the Tornado pumps - they are great

Harbor Freight #14287 - ~$10 on sale
The claim of 59" lift seems to be about right. "190 gallons/HR"

Real numbers:

Consumes ~19W; not real accurate timing of 1l is ~ 5 seconds at ~12" 'head' , 3600/5 = 720; 720/3.76 = 191.48 gallons/HR. That is close enough for me.

I bought 2. One will be a spare.

Ron

3-phase is something you and most other folks do not have. In the US we have 120V (a sine wave at 120V and a neutral), 240/220V (it varies) made of two 120V 180 degrees apart (picture two sine waves with opposite timing and magnitude..when one is at max the other is at max in the minus direction so they add up to 240V. 3-phase is something altogether different...

Nocky mentioned in his post that he bought a solar powered pump and it did not perform as advertised. Has anyone used a solar powered pump with success? What about a battery back-up? I'm trying a small 100l system and I am wondering if I could go solar.

Thanks

Battery and inverter works well for me as the backup pump

Brand & Model - Ebara Optima
Capacity - 8500L/h
Electrical - 240V, 250W
Max head - 7.5m
Cost - $240
Duty Cycle - 15 minutes on 45 minutes off, 24hours a day
Start Date - 1st January 2008
Expiry date - 21st July 2008

When it was working, it was solid, expected it to last a big longer than 6 months... especially for the price and from the reviews I've read. I'll let you know how the warranty claim goes.

Your a lot calmer than I would be......you paid top dollar for what is suppose to be a good pump. Make em pay.

some tips on choosing pumps and improving your pump's performance:

first a note about pump types:
Centrifugal pumps are not positive displacement pumps (i.e. a piston pump positively displaces the same amount of water with each stroke of the piston).
You cannot smother a positive displacement pump. Impossible. If you try to do that, either something will burst or the motor will stall and burn out.
Positive displacement pumps typically have an energy efficiency of 85-90%.
Positive displacement pumps are expensive and need maintenance.

Centrifugal pumps are much more affordable and very reliable.
But they can be smothered. If you put a ball valve on the pump's exit and slowly close it, the pump will continue working, but more and more of the water is slipping between the impeller and the housing and more and more energy is transformed into noise and heat.
Centrifugal pumps typically have an energy efficiency of 40-65%.

centrifugal pumps are designed to have the best efficiency at a specific combination of capacity and head occurring at the same moment.

Posting max. capacity and max. head of a pump given by the manufacturer is irrelevant, since these never occur at the same time: at max. capacity a pump will not overcome any head, at max. head almost no water will come out of a pump. It will be smothered.

The thing to post is capacity @ head. This can be derived from the chart which any good pump will provide.

This allows you to calculate pump efficiency if you also know the power consumption.

how to calculate pump efficiency:

pump effect (kW) = head (bar) * volume (l/min) / 600

pump efficiency (%) = pump effect (kW) / energy input (kW)

Example: Brand & Model - New-Jet pump NJ3000 gives
2700 l/hr @ 0.38 m head
and
500 l/hr @ 2.63 m head

I have put all the available data in an excel sheet:

per hour per minute head in m head in bar pump effect input efficiency
per hour per minute head in m head in bar pump effect input efficiency
2700 l/hr 45 l/min 0.38 m 0.038 bar 0.003 kW 0.055 kW 5.2%
2500 l/hr 42 l/min 0.75 m 0.075 bar 0.005 kW 0.055 kW 9.5%
2200 l/hr 37 l/min 1.13 m 0.113 bar 0.007 kW 0.055 kW 12.6%
1800 l/hr 30 l/min 1.50 m 0.150 bar 0.008 kW 0.055 kW 13.6%
1500 l/hr 25 l/min 1.88 m 0.188 bar 0.008 kW 0.055 kW 14.2%
1100 l/hr 18 l/min 2.25 m 0.225 bar 0.007 kW 0.055 kW 12.5%
500 l/hr 8 l/min 2.63 m 0.263 bar 0.004 kW 0.055 kW 6.6%

ooops, just found out that one of my pumps is very energy inefficient
please help me find a better one

still you can see that this pump was designed to best perform at between 1.75 and 2.00 m head.

this is the only serious way to compare pumps.

design your system, define head and capacity, then go play with the charts to choose the right pump.
To my opinion propeller rather than impeller pumps are the best choice since they are designed for high capacity at very low heads which is what we want. they are just not easy to find.

now for the tips,

1. pump only straight upwards directly to the head you wish to obtain
2. after that, let gravity do he work and use open gutters rather than closed pipes.
3. over dimension the vertical stand up pipe from the pump to the head
4. over dimension all return pipes or gutters
5. to compensate for over dimensioning, only use thin walled drain pipes/gutters: they are MUCH cheaper and they will easily withstand the small head needed in an aquaponics or aquaculture setup. Over dimensioning them has the further advantage of giving you more rigid pipes, so you can put much less supports.
5. avoid all possible unnecessary appendages, pressurized filters, ball valves, etc... This is easy, it will simplify your system and save you a heap of dollars.
6. take the misses out for dinner with the savings

Greetings

Frank

Excellent stuff! Answers a lot of questions.

Thanks Frank, that certainly helps immensely

Damn you Frank, now I have found out all the things I have done wrong

Well done Frank, now I have an excuse to redesign my system

thank you folks
I really needed this.
I have been bashed on another forum for daring to suggest that some improvements might be possible.

the subject was aeration.

you might entice me to stick my neck out again (it is down so deep it will take me some time to find it) and post it here too.

so thanks again

greets

frank

This may seem like a stupid question, but I am going to ask it anyway
Has anyone checked that a centrifugal pump draws the same amperage at various heads?

the only stupid question is the one not asked

in theory wattage, thus amps stays constant with a centrifugal pump as it sort of auto regulates by pumping more water @ lower head and less water @ higher head.

but no, I never checked

frank