Backyard Aquaponics
A place to discuss aquaponics

I would like to see I'd an eductor using a stream of high pressure air might make a better airlift pump. Right now all of the airlift pump designs I have seen are quite unrefined.

Okay,

So given PLJs clarification and tofu's insight my question is pretty much answered. And along with SV I'll be setting the idea aside unless better data is available.

Since the very small motive nozzle is required, and we tend to use low pressure pumps, I conjecture that pushing water through the motive nozzle will result in significant head increase and flow decrease.

So, for the application of increasing ft input flow and stirring solids I would expect them to have little value, as the addition flow increase would be largely offset at the motive nozzle.

For application as an aerator... Maybe, but consider that more flow=more splashing without the eductor.

Anyone concur?


Edit- LOL, although that video is pretty impressive. Wonder what it looks like without the nozzle.

Ron's questions is still valid. Though I suspect that with commodity equipment you will run into a similar trade off

Thats the comparison that needs to be done

Ok SV Im ready to debate the power usage on pumps.

If you restrict a pump the output in watts will decrease but the power usage will increase becuase the amps are increasing as the restriction becomes greater.

Power usage is directly related to current draw... more load, more current draw, more power usage, more cost.

Is that with open impeller type pumps? An engineer friend told me that open impeller pumps can be different to enclosed ones. The open impeller ones like pond pumps can spin freely in the water.

You can argue all you want. You are still wrong
You are confusing AC and DC motors.
And are really confused with your power rules.

DC motors increase power draw with load, ac motors increase power draw with speed.
Increasing load on a dc motor increases current draw, like you are suggesting.
AC motors work differently.
The current draw is directly related to motor speed, so increased load reduces flow, which reduces impellor speed, which reduces draw.

With power, Power (Watts) = Voltage (V) x Current (Amps)
So on an ac motor the voltage is staying the same, so if power drops, the current draw has to drop with it.

More load, less speed, less current draw, less power usage, less cost.

Nice explaination.

Thank you

Its not an argument.... its a debate Andrew.. tut, tut!

Im not confusing anything.

Ive discussed this with one auto electrician and three high voltage electricians today and they all tell me that your wrong.... thats good enough for me.

Ill get some notes together tomorrow and explain... hey, you may learn something.

One question charlie....

Have you measured it ?

I thought the same as you.
So I connected to a power meter to test my theory.
I has seen it with my own two eyes.

Dont ask an auto sparky. What do they know about ac power?

i'm an auto sparkie and a mech engineer, the Mrs is also a mech engineer and we have been both taught (at different uni, auto sparkie school doesn't go into pumping) that when using impeller type pumps (which is the type of pump that pond/waterfeature pumps are) flow reduction causes less power consumption.

does it have any effect on pump life?

Nope.