Backyard Aquaponics
A place to discuss aquaponics

Nice little pump Stuart, bit power hungry but if you wanted to move crap that certainly seems to be able to do it. .

You raise an interesting point. I have a DO probe measuring my DO in one tank with 7 x 50mm air stones. I am currently running a DO of 8.7 at 19.06 - 19.25C.

You can see the air colum breaking the surface but it is hard to see the 30mm rise above the water. The DO and Temp probes are too the left.


Water return is via a vertical and horizontal pipe with 5mm jets below the water line. A few more 5mm jets above the water line as visual notification the pump is running ok. This keeps the tank water moving.


I will go out side after dinner and convert the water return so that it drops the water in about the same place as the air stones. Once the air stones are removed we will see what DO is produced.

That is the best I can do for a comparison as I do not have any Ventures handy.

I've got an atlas scientific DO probe but I haven't got it working yet. Kudapudacat said he would help me and I haven't got down to see him yet.

I often wonder how much d.o can be achieved simply by turning the bottom of the tank over with the top so that d.o rich water at the surface is taken to the bottom... A low wattage power head style pump could do this easily

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Stuart that is the same probe that I am using. Did you get a Dissolved Oxygen Circuit board with it.

Yep and I've also got the maintenance kit. I don't have the other "bits" I need which I think includes an arundino board and stuff.

How well is it working?

I do not have any problems with it. I rinse it in tap water once a month but that is a bout it. DO is still 8.08 about 30 minutes after I made the change and removed the air stones.

have you tried the venturi as an air jet?
have it just out of the water shooting back down

just a thought

Ah don't know what you mean

using the venturi, lift the end out of the water just like the photo of the jet...

also try putting the venturi at the end of the hose as the air bubbles join up the longer it is in a hose

If I lift it out of the water I am pretty sure that more air will be entrained but then it is not acting as a venturi but as a water jet that is less power full.

Hi all

24hours has passed and at 19.25C I am getting a DO of 8.08 with the water just dropping into the tank from about 50mm & 2,500L/H.

That is a drop of 0.62 from running 7 x 50mm air stones. So in winter I may just be able to do with out the air stones. I also think that most of that DO is coming from the turbulence in the rest of the system.

Tonight I have just let the water come out of the 32mm pipe with out reducing the size. So I will see what the produces.

After 24 hours with a venturi running on the same water flow the DO is still 8.08 at 19.25C. So the venturi is running the same as the water jet on my system. I will replace the under water jets ans see how the DO goes without the surface disturbance.

It may be that a DO of 8.08 is the norm with the turbulence air rating the water in the sump.