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Houliham
03-31-2011, 11:24 AM
I have a raft system and a chop system. The chop system is taking off with the lettuce. The raft system's lettuce is growing real slow and is starting to get little black dots on the leaves. Any suggestions?

keith_r
03-31-2011, 11:48 AM
are you adding air to the raft tanks?

Houliham
04-01-2011, 10:00 AM
yes there a have bubble stones.

urbanfarmer
04-17-2011, 11:05 PM
You don't need to add air to your floating raft system if you're growing lettuce! :-)

davidstcldfl
04-18-2011, 06:43 AM
You don't need to add air to your floating raft system if you're growing lettuce! :-)

Wow, this is a first Urbanfarmer....that is, I disagree with your advice to some degree. Of course there are lots of variables....how much water, how many plants, tempt of water, length of the raft beds, ect.
I have seen pictures of other people's raft systems...it was obvious 'where' the air stones were located, because there was a noticeable size difference in the lettuce plants. They were much larger near the air stones.
In general, it's better to have more air then not. Especially now that the water is getting warmer.

Houliham, I too have a mixed system, my lettuce does grow faster in the gravel beds then in the rafts. I guess because of the concentration of nutes in the 'sludge' building up in there :D .
The growth of the lettuce in the rafts has improved as the system has matured. I do add a little liquid iron...I also use Maxicrop with iron.
I find the lettuce does better when the PH is just under 7...6.8 seems to be good for my system's lettuce.
Sorry, not sure what your black spots are...? I haven't had that issue.

keith_r
04-18-2011, 08:03 AM
if the roots in the raft are dark colored or black, it's root rot, and the roots need more oxygen..
raft systems definitely need oxygenation!

urbanfarmer
04-18-2011, 10:39 AM
Good, I was hoping to turn a few heads (pun intended)! I recently sat through a lecture with Dr. Tyson. He's a hort science guy from UF and the Director of the Orange County extension. He stated that floating raft systems didn't need added oxygen; so, of course I had to question him. He proceeded to display pictures of different farms that raise crops hydroponically without any aerators. The local farmers here in Florida grow with no aerators or pumps!!! Their yields are not affected, and they have found that they don't get any difference by adding these devices. I was as shocked as you were, but not is it only scientific fact, but many many farmers are doing this here in central Florida!!!

He did state not ALL vegetables and fruits can be grown like that. It is possible to have a specific species of lettuce that can't grow in there, but in general he did state lettuce can and will grow without added oxygen or a reduction in yield. Also, the accepted way to grow plants that want more oxygen is not to add aerators, but to provide a gap between the water and the roots at the top. :-)

University of Florida raft system example: http://edis.ifas.ufl.edu/hs184

davidstcldfl
04-20-2011, 07:19 AM
Wow...that's interesting U. F. I wonder if there is some difference between the hydro and the AP systems ...? I wonder how often in the hydro, they change water (keeping the DO up)...?...don't they have issues with some kind of bad bacteria attacking the roots....?
I wonder how many 'actually tried it' both ways....or are they just doing what others are doing ?
Did he happen to give you any links to some documentation ?

I took some lettuces to the flea markey in a small floating raft set up. The 1st weekend, I had no air ( or water movement) and the roots started getting dark by the end of the 1st day. The 2nd weekend, I had a small air pump and a few stones...the roots/plants seemed better. The water wasn't very deep. Not exactly 'scientific', but the results where obvious. The air temps were about the same both weekends.

I'm waiting for permission to post a picture....it shows an AP trough of lettuce ( in rafts) and the lettuce over the air stones are much larger then the rest. ( I don't know what the flow rates were, or the PH and other factors of the water in the picture)

Here's 2 links to a news letter from Friendly's Aquaponics, in regards to what they have found about added air in their AP systems... scroll down and look for 'Aeration In Aquaponics Systems'
http://hosted.verticalresponse.com/5273 ... 51f16240b/ (http://hosted.verticalresponse.com/527375/990fe8f2ff/1451002247/851f16240b/)
http://hosted.verticalresponse.com/5273 ... 51f16240b/ (http://hosted.verticalresponse.com/527375/197a440b0b/1451002247/851f16240b/)

Friendly's is doing tests on reducing the water 'flow' through the troughs and increasing the DO instead. They think there is less power needed to add air VS. the power to move the water. (Of course, there are lots of variables on the different pump ratings) Every little reduction in power counts...especially for what they pay in HI.

urbanfarmer
04-20-2011, 02:11 PM
I haven't looked for anything specific because so many hydroponic/aquaponic farms are apparently doing it this way. I believe the trick is adding a gap that's few inches between the bottom of the raft and the top of the water for oxygen hungry plants (this is why I have seen in EDIS (http://edis.ifas.ufl.edu/) articles). I haven't really looked into it because he was more than confident about it and he showed so many examples of farms that did this and have been doing it for years if not decades. Also, we have a local restaurant called Scorpio's and they have this exact setup outside with basil and lettuce (in front of the restaurant). I looked, and they don't even have a gap under the raft and they go from seed to harvest without adding any oxygen. It's just a barrel with water and a styro raft on top. They also have this setup at the demo garden at the Orange County extension, and it's growing great: http://edis.ifas.ufl.edu/hs184

I don't put much faith in companies that sell training and materials for the same system designs they are supposedly "researching"... seems like a conflict of interest at a minimum... To be honest, I think any of these companies that charge $1500 for a 4 day seminar for training on aquaponics could care less about the quality of the material they put out. There is plenty of scientific information out there, and there's no reason why they make up concepts or explanations for things instead of doing the research and presenting the facts... you definitely don't get what you pay for. Not a fan of Friendly's to say the least... Anyway... I digress.

I think more information needs to come out in a practical format so people have the right facts about aquaponics. Knowledge on how to feed yourself and your family should not be sold to the public for a profit... ESPECIALLY if it's not right... OK, I'm off topic... sorry... this is just a real issue that peeves me off, and I'm so glad we have a forum like DIYAP to help people out, out of the good of our hearts and not to fill our wallets...

davidstcldfl
04-20-2011, 03:31 PM
Your right, most of the AP experts selling stuff/systems are...well, questionable. I've read enough about Friendly's set ups and have actually looked at one of their commercial set ups over in Brooksville FL. Pretty impressive.
I know the owners....I can hook you up with a free tour of the one in Brooksville...so you can check it out first hand...? Since your in the Master Gardener's program, 'maybe' they'd even let you 'sit in on' the next commercial classes in Oct.

Sure, Friendly's AP are making money by doing the classes, but they are also making money with their AP set up. If it doesn't produce, they don't make money. ( un-like science that has a budget that they 'must spend to get more'...on whatever they are trying to prove :P )

For sake of argument, lets say their system does work....
you pay them 1500 for the 4 days,all the books,the plans, and the hands on training......or....
you do like I did, sit in front of the computer for countless hours trying to find info, hopefully from some one that actually knows....then you try this and that, till you get it right. Thank the Lord, I did get lots of good help here and got to see a few systems in person (which only made me want to spend 'more' time changinfg stuff...lol) Your paying, one way or another.... :P :lol: :roll:

Back to adding more air....

If the bottom of the raft isn't in the water...you lose some good surface area for the bacteria to grow on. The Dr's idea of having 2 sheets of styro, with the hole in the top one being bigger and filled with vermiculite (or was it perlite...maybe hydrotron would work too) sounds like it would be a great way to give more air to the plants ( I think he was talking about tomatoes)



here's a picture of spinach grown in a test by A.U. The left has added air...the right doesn't.
http://i931.photobucket.com/albums/ad157/davidstcldfl/airhelps.jpg

rfeiller
04-20-2011, 03:51 PM
Passion is a good thing.
Oxygen is being introduced where and how is what I'd like to know. The chemical cocktails are complex that the large growers are using. They have developed systems that apparently are industry standards in your area.
See what you can find out urbangardner, a lot of Hydroponics in my area haven't found large aquaponics.

I can understand charging for information. There was a time when people from around the world would call day or night demanding I teach them everything I knew for free so they could raise thousands of discus and become millionaire's the fact I had invested many years in developing my system didn't matter to them. When I would refuse they would become rude and angry.

urbanfarmer
04-20-2011, 04:08 PM
Your right, most of the AP experts selling stuff/systems are...well, questionable. I've read enough about Friendly's set ups and have actually looked at one of their commercial set ups over in Brooksville FL. Pretty impressive.
I know the owners....I can hook you up with a free tour of the one in Brooksville...so you can check it out first hand...? Since your in the Master Gardener's program, 'maybe' they'd even let you 'sit in on' the next commercial classes in Oct.
David, that would be really great. I could not pass up an opportunity like that! :-) As I have told many people, Friendly's training seems the most comprehensive based on their outline (click) (http://www.friendlyaquaponics.com/docs/Friendly%20Aquaponics%20Commercial%20Training%20Ou tline.pdf). However, I have spoken with several people that were "unimpressed" with the training and felt they did not get their money's worth. The trainings from other companies I have seen were definitely not worth the money. There's way more information on the Internet for free, and most folks would be better off joining a forum like this one to get started. On more note though, I am not saying that their system would not necessarily work. If one guy tells you to buy $5000 worth of air pumps and another guy tells you to simply life the rafts up a few inches (practically no cost) and both systems yield the same... well they both work, but in my opinion spending the $5000 is stupid in this case. A lot of these trainers may have in fact created a system that works, that I don't doubt, but they start talking about the "science" behind what and why, and they're literally blowing air out their @$$ because they really don't know, made stuff up (not to deceive anyone they think they're right), or heard something through the grapevine that's just not true. A perfect example are these "rules of thumb" regarding ratios. Most folks get told one thing or another, and the ratio only takes into consideration grow bed area and tank gallons and fails to address the fish mass and feed rate. Dr. Wilson Lennard has a tool that tackles this on his website for backyarders... ANYWAY, I hope you see what mean :?

urbanfarmer
04-20-2011, 04:12 PM
Back to adding more air....

If the bottom of the raft isn't in the water...you lose some good surface area for the bacteria to grow on. The Dr's idea of having 2 sheets of styro, with the hole in the top one being bigger and filled with vermiculite (or was it perlite...maybe hydrotron would work too) sounds like it would be a great way to give more air to the plants ( I think he was talking about tomatoes)



here's a picture of spinach grown in a test by A.U. The left has added air...the right doesn't.
http://i931.photobucket.com/albums/ad157/davidstcldfl/airhelps.jpg
I will try to find more specific research on this as I am sure it has been done, but the farmers here in FL have tried adding air (because this is what they hear through the grapevine) and have discovered it made no difference in their yields. I mean these guys make a living off these VERY SIMPLE designs. If we slash away the crap in most systems with Occam's razor or hell just apply the K.I.S.S. principle, commercial producers can save money on initial equipment costs, maintenance, consulting and training fees, and possibly avoid other unexpected complications from complicated system designs!!!

urbanfarmer
04-20-2011, 04:35 PM
Passion is a good thing.
Oxygen is being introduced where and how is what I'd like to know. The chemical cocktails are complex that the large growers are using. They have developed systems that apparently are industry standards in your area.
See what you can find out urbangardner, a lot of Hydroponics in my area haven't found large aquaponics.
Well, assuming you have a gap or some exposed surface, oxygen can enter the water there.

Also, below is not a complex chemical cocktail nor is it technologically advanced compared to anything :lol: tee hee

Add water-soluble fertilizer, such as 20-20-20 with micronutrients, at a rate of 2 teaspoons of fertilizer for each gallon of water used in the water garden. In addition, add Epsom Salts (magnesium sulfate) at a rate of one teaspoon for each gallon of water. Use a soft broom to mix the water & fertilizer in the garden or premix all fertilizer in a bucket before adding to water garden. http://edis.ifas.ufl.edu/hs184


I can understand charging for information. There was a time when people from around the world would call day or night demanding I teach them everything I knew for free so they could raise thousands of discus and become millionaire's the fact I had invested many years in developing my system didn't matter to them. When I would refuse they would become rude and angry.

You have a point... Human nature can be very ugly... I'm no Ghandi. I have no idea where we can start, but I do know that I will try to help people if I can. Obviously, as a Master Gardener I help people for free all the time, and I have experienced folks that get rude and angry because they don't get the answer the want. It's pretty unreal, but those folks are few and far between. Who knows... :shock:

rfeiller
04-20-2011, 09:03 PM
i believe in helping others when given the opportunity, that is my responsibility as a human being.

the hydroponic farms in my area are considerably more complex then 20-20-20. i know of no commercial operation that uses 20-20-20. each time the solution is circulated the water is striped and new chems are automatically injected into the solution specifiically formulated for the crop being grown. total computerized lighting (natural and artificial), chem injectors, carbon dioxide, oxygen. real estate is too valuable out here to leave it to chance.

i can't imagine even a large commercial aquaponics set up not tweaking and adding nutrients that are compatible with the fish. they are in business to make money and not the business of sharing information.

davidstcldfl
04-21-2011, 06:26 AM
David, that would be really great. I could not pass up an opportunity like that!
This is a tour of an organic, aquaponic commercial farm in/near Brooksville, FL....using the Friendly's set up....troughs with floating rafts.

They have free tours on the 1st and 2nd Saturday of the month. The next one will be May 7th...at 10:30. They like to have RSVP, because, they try to keep it to less then 30 people. If anyone is interested, RSVP here....(email works best, most times they are too busy to really have a chance to talk on the phone)
http://www.greenacreorganics.biz/contact_us.html

davidstcldfl
04-21-2011, 07:27 AM
I started to do a little search on 'hydro' culture, since I'm not too familiar with it. Man, I didn't know there were so many sites for hydro 'cash crops'... :lol:
Now I see how it's possible 'not to' have extra air in 'static hydro'....Like U.F. said, have the roots up out of the water/nutes some by having part of the raft out of the water.
One static display I was reading about, was changing the water/solution once a week...that would keep up the DO to 'some extent'
In NFT....I found they said the plants would run out of nitrogen on 'long' runs 'before' they actually would lose DO ( on fast growing plants). On long runs, they said you could just add more nute solution at a 2nd entry point at about 1/2 ways.

So in "hydro' one can get along with out extra air.

That's what I was asking earlier....what's the difference between the 2 systems...?...Why could hydro get along without added DO ?

Since aquaponics IS different then 'hydro' the same guidelines won't always apply to both. Since AP is trying to mimic nature...we know added DO has to help the overall system. Between the fish, veggie plants and the bacteria...more DO is better.

I would still would consider Friendly's info on DO and water flow to be 'at least' a good starting point. If anyone is really 'pasionate' about this. Perhaps, do your own testing of their figures...I'd be the 1st to like to see the results.

urbanfarmer
04-21-2011, 09:24 AM
OK great I will contact them. Thank you

Yes, lots to consider and more research is needed. I just want to add that I had a floating raft system with no added oxygen and the plants were doing great. I left about 2 inches of a gap between the raft and the water. I had different kinds of lettuce and 1 onion plant (just to see) (56 heads of each type of lettuce with 8x 2'x4' rafts). The reason I "had" it is because when the storms came through it damaged the foundation and then it collapsed a few weeks later. I was going to surprise you guys with the pictures and my data/research on it... Each head of lettuce was sitting in a peat pellet (which actually isn't the best, but cheap) and they were still doing fine with no root rot or signs of disease. Anyway, this was supposed to be my experiment, but it got destroyed. I will rebuild it at some point, but currently I don't have the time. I think it can work, but like you said, someone needs to at least try it long term or research needs to come out specifically for aquaponics!

urbanfarmer
04-21-2011, 09:31 AM
i believe in helping others when given the opportunity, that is my responsibility as a human being.

the hydroponic farms in my area are considerably more complex then 20-20-20. i know of no commercial operation that uses 20-20-20. each time the solution is circulated the water is striped and new chems are automatically injected into the solution specifiically formulated for the crop being grown. total computerized lighting (natural and artificial), chem injectors, carbon dioxide, oxygen. real estate is too valuable out here to leave it to chance.

i can't imagine even a large commercial aquaponics set up not tweaking and adding nutrients that are compatible with the fish. they are in business to make money and not the business of sharing information.

For starters, it definitely depends on what you are growing. The examples he gave of successful small farms had no equipment running whatsoever, but they were only growing lettuce. They had the floating rafts in a greenhouse, and that's it. We didn't discuss the fertilizer in detail, but I am fairly confident they were not using anything too expensive. From a business perspective, there's no reason to increase your cost of production when there are viable alternatives that costs considerably less. With that said, I know we have all seen the hydroponic farms with all kinds of gizmos and gadgets. All I can say is that they keep it real simple down in these parts, and the restaurant Scorpio's I mentioned seems very happy with their 20-20-20 and no added oxygen setup. If the consumers like the product and the businesses are capable of producing at lower expenses, why can't that be a reality? I leave you with that thought... :mrgreen:

keith_r
04-21-2011, 07:26 PM
so is this a hydroponic site or aquaponic? :o

just kidding..
but, ap and hydro are completely different animals.. with fish in the mix, added oxygen is essential... it's not just about what is "sufficient" for the plants, but the what is the optimum balance.. :mrgreen:

urbanfarmer
04-21-2011, 10:05 PM
so is this a hydroponic site or aquaponic? :o

just kidding..
but, ap and hydro are completely different animals.. with fish in the mix, added oxygen is essential... it's not just about what is "sufficient" for the plants, but the what is the optimum balance.. :mrgreen:
You make an excellent point. Fish typically need a minimum of 4 ppm DO whereas plants barely need 2 ppm DO. Therefore, wouldn't the fish being alive indicate we have enough DO in the system? :lol:

I don't have a high density system, but my AP setup has no aerators besides the agitation from the water return. 1 pump and that's it. The fish grow fine and so do the plants, even when I had the floating raft system.

Last point, aquaponics is hydroponics as far as the plants are concerned. Try, if you will, to illustrate just what a plant needs that is different in aquaponics than in hydroponics. AHA! :mrgreen: (keep in mind the limiting factor for the DO is the fish not the plants as the plants needs about half as much DO as the fish to survive)

rfeiller
04-21-2011, 10:21 PM
without a doubt the bottom line is the nutrients needed by the plant does not change whether it is aquaponics/bioponics or hydroponics or does it? bioponics of any sort have mychorriza, fungi, bacteria, that aid in the absorbtion of nutrients by the plants whereas hydroponics does not offer these advantages and must rely on the correct pH for the proper absortion of nutrients?

urbanfarmer
04-21-2011, 11:29 PM
Traditional hydroponics can have mycorrhiza whether intentional or not. With that said, have you ever seen mycorrhiza on your roots in aquaponics? I have not seen my roots show signs of it. Even so, that doesn't really change things. In hydroponics like we have or traditional hydroponics, the water flows across the roots pretty readily. As shown by research, the more water movement there is the lower the nutrient levels can get because the plant is still able to absorb the nutrients it needs.

None of this has any bearing on the dissolved oxygen levels. :twisted: