Trough aeration increases plant growth!!

[Chris Smith]

I have seen several aquaponic farms in the area that have been adding supplemental aeration in their troughs and getting dramatic increases in plant growth in the immediate area of the aeration. Seeing this happen has prompted me to add aeration to my troughs. I just got done running main lines with a blubber every 4 feet in my troughs. I hope to increase my plant growth with the extra DO.

I plan to add an air stone every 2 square feet in my micro system as experiment to compare to the commercial system.

My current theory and direction are going toward a low water transfer of about 2 gpm through the troughs and high aeration. I will down size on the water pumps and add to the air pumping capacity. My electricity costs $.44 kw hr so I want to get the systems as efficient as possible.

 

 

[Christian James]

the other question is if it's the root agitation or the actual dissolved oxygen that improves the plant growth?

[Kobus Jooste]

I have been following this discussion for a bit and want to throw in a question.  If the rafts benefit from having oxygen and water in contact with the roots, what would cost more and work better: submerged roots that are aerated, or having spray bars in the raft structure that are pump driven?  Obviously with the latter, if there is a power failure, the roots will be at risk of drying out, but I was wondering about the viability of modified aeroponics on a large scale

[Michelle Silva]

Kobua, I like that idea. I don't have an air pump and would like to figure a way to not have that extra expense. I recently changed the fish tanks to have more airtion into each. I also have 55 vertical stacks that also recirculate back to the raft tanks and was thinking  I might try increasing the amount of times I water those to increase oxygen, I only do it three times a day now.

I was trying to figure out why plant growth doesn't seem to be as fast as the first few harvests I had...possibly a few things here.. the cold weather we had lately here in Florida, more plants now and not enough fish...just added 50 more goldfish so will see if that helps any.

Kobus Jooste said:

I have been following this discussion for a bit and want to throw in a question.  If the rafts benefit from having oxygen and water in contact with the roots, what would cost more and work better: submerged roots that are aerated, or having spray bars in the raft structure that are pump driven?  Obviously with the latter, if there is a power failure, the roots will be at risk of drying out, but I was wondering about the viability of modified aeroponics on a large scale

[Ryan Chatterson]

I would look at the fact that there arent any commercial aeroponic farms in the US as a sign that the technology hasnt been refined enough. You have to have a high pressure pump to force the water through a fine filter before you get to the sprayers or they will clog. With hydro, cleaning the filters is not quite as burdensome but with AP, you have a lot more solids to deal with. As you mentioned, you also have the chance of total crop failure if the filters clog or the pumps stops.

Water pumps generally take more electricity to run then air pumps. If you want to eliminate one of the pieces of equipment, you can run air lifts instead of a water pump and use a single dedicated pump/blower for your air source.

[Ryan Chatterson]

And Chris, have you taken any DO readings(before or after the addition)?

[Kobus Jooste]

I'm sure you guys are correct about the cost benefit analysis, but it is still something I would like to try.  I have made small pvc spray bars (larger holes in it than typical aeroponics I think) that could produce a decent spray, but may not clog up on pre-filtered AP water.  Likely a gimmick for smaller systems though :)

Ryan said:

I would look at the fact that there arent any commercial aeroponic farms in the US as a sign that the technology hasnt been refined enough. You have to have a high pressure pump to force the water through a fine filter before you get to the sprayers or they will clog. With hydro, cleaning the filters is not quite as burdensome but with AP, you have a lot more solids to deal with. As you mentioned, you also have the chance of total crop failure if the filters clog or the pumps stops.

Water pumps generally take more electricity to run then air pumps. If you want to eliminate one of the pieces of equipment, you can run air lifts instead of a water pump and use a single dedicated pump/blower for your air source.

[Chris Smith]

I have not taken any readings since adding the bubblers. I just finished the project yesterday. The last reading was 4 in the troughs so I assume that it is higher now. I do not own a digital meter but can borrow one again soon. I was using a test kit that involved lots of steps and many drops. I found that it was not accurate when compared to the digital meter. My plants were growing fine with the DO at 4 but I want to increase the growth rate. I diverted some of the air that was going to my fish tank over to my troughs. I used many small bubblers and each one has a 1/4 drip irrigation valve so I can adjust the amount of air at each stone. I did not add any extra air pumping capacity. The fish seem to be fine. Their tank is now a mellow jacuzzi. It seems to be enough air and water moving to break down the solid waste.

Ryan said:

And Chris, have you taken any DO readings(before or after the addition)?

[Chris Smith]

I am currently working on an aeroponic component  that will add on to one of my systems. I have a different approach than spray bars and anything that can clog up easily. I will post on it once it is running.

Kobus Jooste said:

I have been following this discussion for a bit and want to throw in a question.  If the rafts benefit from having oxygen and water in contact with the roots, what would cost more and work better: submerged roots that are aerated, or having spray bars in the raft structure that are pump driven?  Obviously with the latter, if there is a power failure, the roots will be at risk of drying out, but I was wondering about the viability of modified aeroponics on a large scale

[Michelle Silva]

Just FYI,  haven't had any clogging issues yet (3/8" feeder tubes come off the main tube) over the verticals...hoping the pressure will be enough to keep them clear,plus the only go over there once water has made it up and back through the three rafts.

Chris Smith said:

I am currently working on an aeroponic component  that will add on to one of my systems. I have a different approach than spray bars and anything that can clog up easily. I will post on it once it is running.

Kobus Jooste said:

I have been following this discussion for a bit and want to throw in a question.  If the rafts benefit from having oxygen and water in contact with the roots, what would cost more and work better: submerged roots that are aerated, or having spray bars in the raft structure that are pump driven?  Obviously with the latter, if there is a power failure, the roots will be at risk of drying out, but I was wondering about the viability of modified aeroponics on a large scale

[Michelle Silva]

"Water pumps generally take more electricity to run then air pumps"...? The water pump I have from Aquatic Ecosystem uses 95 watts of energy (950 GPH). Cost was around $100. I was originally advised that I needed to have an air pump and air stones when I was first setting up from a few others... didn't get one because the ones I found were so expensive, plus the addtional cost of all the air stones and thought I would try first to see how well it works without.

I'm curious what the DO is at and will be borrowing one soon to check. What is the preferred DO level?

Ryan said:

I would look at the fact that there arent any commercial aeroponic farms in the US as a sign that the technology hasnt been refined enough. You have to have a high pressure pump to force the water through a fine filter before you get to the sprayers or they will clog. With hydro, cleaning the filters is not quite as burdensome but with AP, you have a lot more solids to deal with. As you mentioned, you also have the chance of total crop failure if the filters clog or the pumps stops.

Water pumps generally take more electricity to run then air pumps. If you want to eliminate one of the pieces of equipment, you can run air lifts instead of a water pump and use a single dedicated pump/blower for your air source.

[Kobus Jooste]

Had to giggle at my own caution here.  I thought the same thing, but then checked my near identical response because I thought things may be different in the US!  A 45 Watt water pump drives my large research greenhouse, while the smallest vortex blower I could find, at 70 watts, cannot push air below 1 meter in depth.  I quietly think there is scope for pump-driven large systems without air stones.

Michelle Silva said:

"Water pumps generally take more electricity to run then air pumps"...? The water pump I have from Aquatic Ecosystem uses 95 watts of energy (950 GPH). Cost was around $100. I was originally advised that I needed to have an air pump and air stones when I was first setting up from a few others... didn't get one because the ones I found were so expensive, plus the addtional cost of all the air stones and thought I would try first to see how well it works without.

I'm curious what the DO is at and will be borrowing one soon to check. What is the preferred DO level?

Ryan said:

I would look at the fact that there arent any commercial aeroponic farms in the US as a sign that the technology hasnt been refined enough. You have to have a high pressure pump to force the water through a fine filter before you get to the sprayers or they will clog. With hydro, cleaning the filters is not quite as burdensome but with AP, you have a lot more solids to deal with. As you mentioned, you also have the chance of total crop failure if the filters clog or the pumps stops.

Water pumps generally take more electricity to run then air pumps. If you want to eliminate one of the pieces of equipment, you can run air lifts instead of a water pump and use a single dedicated pump/blower for your air source.

[Ryan Chatterson]

The perfered DO level would probably depend on who you ask but I say as close to saturation as possible. O2 is directly related to growth rates so the higher the better (unless you get into pure oxygen but thats a different story). The actual amount in the water will depend on the water temperature. The colder the water, the more O2 it can hold. Get your water temp, then stick it into google and look at the saturation level. Compare that with your reading and it will give you an idea of where you stand and where you want to be.

As for the water pump/air pump...it's kind of like comparing apples to oranges so I shouldnt have just said it's cheaper. It will of course depend on the price of the pumps in question, shipping, warranties etc but if you design your system with close water levels so that you are able to utilize airlifts, you can cut down on the power needed considerably. You can pump 1200gph with 1cfm from a $60 airpump (25w) if you design the system with farily close water levels and use the correct size piping for the airlifts (several 1/2" - 3/4" pipes vs a single 1 1/2" pipe).

I helped design a 4 trough raft system utilizing only airlifts for a lady about a year ago and it works great. Doesnt chop up solids, low watt draw, 1 pump for the entire system, etc...just need to keep a close eye on water levels during the planning/building. :)