DIY Backyard Greenhouse Aquaponics Project – Venturi Aerator

As I talked about in my series on the DIY Backyard Greenhouse Aquaponics Project, I wanted to add a venturi aerator fixture to the pump supply line that Tees off and returns back to the fish tank.

This was a very easy project to do, and didn’t take much time to complete.

Update: I made a small modification to the venturi for better flow. See the bottom of the article.

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The venturi

A venturi aerator is a system with no moving parts that is “set it and forget it” simple. The means to power it is having a pump that’s powerful enough to take some of the water and return it to the tank.

As the water flows, it sucks in air and helps to put more oxygen into the water. This is beneficial for both the fish and plants, and lessens the need for air pumps.

For reference I used Rob Bob’s video on DIY venturi aerators, which is a nice video on making one.

Venturi aerator overall

See the pic to the right for the completed project.

Now let’s get into it!

The parts & tools

First, the parts list (PVC unless otherwise noted):

  • 1″ threaded Tee
  • 1″ male adapter
  • 1″ to 1/2″ threaded reduced bushing
  • 2 x 1/2″ close nipple
  • 1/2″ threaded ball valve
  • 1/2″ threaded Tee
  • 1/2″ irrigation tubing adapter, male threaded to barb
  • 1/2″ irrigation tubing, about 3-4″
  • 1/2″ male adapter
  • 1/2″ pipe, about 1.5″
  • 1/2″ to 3/4″ reducer coupling (looks like a funnel)
  • 3/4″ pipe, about 1.5″ plus 2-3′ to get it into the water
  • 3/4″ 90

The venturi construction generally goes in order of this list.

Also needed are a cutting tool (saw or a pipe and tubing cutter), pipe thread tape and PVC glue.

The tubing cutter is nice because it doesn’t spread tiny flakes of plastic EVERYWHERE.

I bought most of my PVC fittings from Supply House, and though I have no affiliation with them, the prices and shipping have been good.

What I also liked is not having to go the store and search for the parts (or worse, ask the non-existent employees).

They had the lowest price for most of the fittings I was looking for (by less than half), as well as having fittings in-stock not normally found in big box stores.

For example, a 1″ ball valve that’s $5.36 at HD is $1.65 from Supply House. They also carry a 1-1/2″ to 1″ slip reducer for the Affnan-style siphon top and a 1-1/4″ barb to 1″ threaded adapter for my pump hose.

Buying these oddball fittings online was the only option, because no one in town has them.

The total for these parts from Supply House was $6.24 as of 3/18, though not included are the small sections of 1/2″ and 3/4″ pipe, and irrigation fitting and tubing piece I already had.

The build

Note: Make sure to use pipe tape on any threaded parts to seal against leaks and get the threads screwed in well. I also suggest dry-fitting everything first without glue. This keeps “oops” from happening quite so often.

Venturi aerator tee and valveMy pump hose threads into one of the sides of the tee. Your connections may be different, so adjust as necessary.

The 1″ to 1/2″ reducer bushing threads into the Tee, then the 1/2″ close nipple and ball valve.

For my situation, I wanted the ball valve to be on top, with the tee pointing to the right.

Next I screwed in another 1/2″ close nipple, and the 1/2″ threaded tee. The open port on the tee faces up.

Inside this tee and irrigation fitting is where the venturi is where the magic happens.

Water rushing past this fitting creates a low pressure area, which sucks in air from the top of the irrigation fitting.

To get this to happen, cut an angle (about 45 to 60 degrees) on the piece of irrigation tubing inside the fitting.

See the pic, it makes more sense.

My irrigation tubing wouldn’t fit inside the fitting. So I had to cut it lengthwise and trim it until it fit inside the fitting.

Venturi aerator half-inch Tee restriction and 90

Screw the fitting and tubing into the top port of the tee.

Make sure the long part of the tubing faces the water flow. Doing it backwards means getting wet!

In the open tee port, screw in the 1/2″ male adapter, then add a short piece of 1/2″ pipe.

Next comes the 1/2″ to 3/4″ adapter, followed by a short piece of 3/4″ pipe and the 3/4″ 90.

Last, put on the longer piece of 3/4″ pipe to get the mixture down into the water.

Venturi aerator bubbles

Adjustments

I had to adjust the height/position of the angled tubing to get the most amount of bubbles into the water.

You should hear an air sucking sound if it’s working properly, and see a good amount of small bubbles from the water.

I leave this valve all the way open unless for some reason I need more flow into the growbeds, or to adjust the venturi.

Update

Venturi aerator V2

Looking at Rob’s video again, I decided the water might be restricted too soon by the 1/2″ ball valve.

So I swapped out the 1/2″ valve, and put in a 1″ nipple and 1″ ball valve, and moved the 1″ to 1/2″ reducer bushing after the valve.

Everything else is the same, and now it looks like the pic to the right.

It seems like I get a little better flow and more bubbles with the 1″ valve.

Summary

For less than $7 $7.02 in parts I built this effective venturi aerator for my backyard aquaponics system.

It was very fast to build, and should help keep fish and plants happier.

 

 

OK, that’s all folks! Do you have any questions or comments about aquaponics, sustainable homesteading, permaculture design or anything else? Ask your question down below and let’s talk! You can also use the contact form, or email me at info at thepermaculture dot life.

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