Backyard Aquaponics
A place to discuss aquaponics

Here's a design using your passive return for extra aeration. Waterfalls are effective at oxygenation for small to medium sized systems but you need the height and volume of water return to supply enough dissolved oxygen.

As long as your return water is enough to fill the narrow end of this design your venturi will kick in adding bonus air as well.

Cool, I was wondering about using a venturi to add air.

It would be nice to reduce the system I have now to using a single pump (I am using a sump pump for a return to aerate the water ala S&S). There are many ideas to pick from on here. I had been pondering a some sort of "sacrificial" side stream with a venturi and mini-showerhead to aerate the water enough, lacking a powered return. (I actually think the sidestream thing is in the barrelponics manual somewhere)

This would work since the feedline doesn't see a pressurized stream.

DAMN ... more ideas to consider... LOL
keep these ideas comming, sooner or later we will all contribute to a 'super system', running perfectly in all areas...

Anyone built a venturi, and can post a picture? I read this link(s) that Johnnie posted and it got the neurons firing...

http://leisure.prior-it.co.uk/build-diy ... ml#buildit

there are quite a few good site for models of venturi intakes

http://leisure.prior-it.co.uk/diy-build ... he_Venturi

plus the diagram above

These 2 sites
http://leisure.prior-it.co.uk/diy-build ... turi.shtml
and
http://leisure.prior-it.co.uk/venturi-mods.shtml

were interesting for me with regard to venturi...

am- venturi is not just what I thought it was.
I remember using a venturi to suck the air
and excess resin from foam sandwich boat building,
..paper tigers a type of light weight twin hull yacht.

So this one guy in England is the only source for DIY venturis? Where is the Aussie pride?!?

we had better put something together then hadn't we!

As far as I can ascertain what the hell this venturis is and what it does and what the guy used to make his all you need to do is:

Get a handful of kids elastasince(non-toxic), cut a hole in the top side of your pipe, stick the plasticine in the pipe to make it narrow and then to rewiden again, stick a straw (or another piece of small piping) in the rewiden part of the elasticine (or mould it around it to ensure no plasticine blocks the small pipe) and bob's your uncle, more air in your water.

I hope that made sense.

Is it silly to say only use it after the pump and after any inclines.

that makes sense... too much air definately affects the ammount of water you pump will put out...
My pump (a retrofitted pool pump) stopps pumping water alltogether when the air builds up in the pump...

am- as you say to much air can make a pump cavetate, wearing out bits before they need be.
Ok if you pump has 'hydroscan" or some such thing to avoid overheating.

Totally agree with both of you, only after any pumps, and after turns could be a good idea. In the documents on the Venturi the guy has it about 20cm's back from where the water takes it's final turn and back into the fish tank.

Cheers,

Duncan.

Good placement of the air inlet. one of the things i remember from trade scoll for trade number one is that the point of lowest pressure occurs a caertain distance AFTER the orific, or venturi "neck"

B2B, do you remember something like this?

Steve