Direct flow through system??

[David Nabong]

Earlier in October I had the opportunity to do the tour at Growing Power's facility in Milwaukee. While everything together is very cool, I naturally left with more questions than when I arrived. The big question is what the recirc system they use is most like? Besides the biofilt from the plant beds; which is gravel, supplemented with compost, an primarily monoculture watercress, and strong aeration, the water goes up and comes down.

The raceways work out to 1 fish per gallon(somewhere in the 10000 gallon range), the water is totally opaque and they harvest truckloads of watercress. However the beds don't appear to be ebb and flow, just gravel beds with fill on one side and drain on the other end. I suppose since watercress is an emergent plant, it can handle being wet all the time, but has anyone ever seen, or used this technique? It seems to be somewhat like NFT, but I'm not real sure.

It would seem to be a relatively easy way to go, if you could do more terrestrial type plants, but like I said the AP systems were more or less monoculture.


Thanks,

d

[Sylvia Bernstein]

Touche, my friend. We have our work cut out for us, and the mountain is high, but that doesn't mean we can't climb it.

[Sylvia Bernstein]

Kobus, it occurs to me that given where you are you might not know about Will Allen and Growing Power. TC and David, jump in here if you think I'm exaggerating, but in my opinion Will Allen is the face of Urban Agriculture in the U.S. He won the very prestigious MacArther Fellowship (AKA the Genius Grant) a couple years ago, has spent time at the White House, and was recently named one of Time Magazines 100 most influential people in the world. Pretty tough for "everyone else must push as hard as they are"! Overall, he is a great spokesperson for bringing attention to the possibilities of growing food locally within an urban food desert. Overall, he is doing much here to make aquaponics known - if someone here has heard of aquaponics chances are they heard it from some association with Growing Power. The problem is that all that publicity is for an aquaponics system that can only grow watercress and water soil filled pots, requires cleaning a couple times a year (I didn't know that David, but it makes sense), is 3" deep, and encourages a 1 lb of fish to 1 gallon of water stocking ratio. I run into people here regularly who confront me with one of these "realities". "Don't you have to constantly clean out your grow beds?" "Can't you stock 1 fish for ever gallon of water? (just got asked that last week)" "I hear you can only grow watercress and lettuce in aquaponics." It is a marketing and education challenge for those of us heavily involved in aquaponics here.

Your question about "what is aquaponics" is an interesting one that I've seen tackled to various degrees on other sites. I'd love to see it posted as a forum topic here and see what happens. :)

[TCLynx]

I definitely see and agree with Sylvia's point. I would hate for people to try their methods (or more likely a simplified version of their methods) and fail only to decide Aquaponics is bunk and give it a bad name.
Just because their heavily stocked, mature, labor intensive method works for them. It definitely doesn't mean some one can start up a simplified version of it and stock it as heavily from the start and expect anything but likely disaster/disappointment.

[David Nabong]

@Sylvia- one thing our tour guide let go, and she visibly was wondering if she should have, was they are purchasing all male tilapia, she did indicate they are looking to implement their own breeding program, however we all know there is a cost effective way to achieve all male populations, and a less cost effective way. Again, I love their message, however, I encourage all to read between the lines of copacetic and pastoral Milwaukee. I can't imagine what the harvested Tilapia taste like, and we were informed they are harvested and processed directly from the raceways.

[David Nabong]

@sylvia, and if the goal of their system is to show people that high quality protein can be raised, and high value crop is easily marketable, along with the pretense of "almost organic" I agree, it does border on heresy. I have also read, and my experience there (albeit a tour, not a weekend workshop) that they are notoriously secretive of their methods, mostly by oversimplifying them i.e. a little gravel here, add seeds, bunch of fish, voila!
@Kobus- they readily admit a gross amount of physical labor, and are glad for the volunteers that come in, especially, as noted in Syl's blog 200+ participants, including cleaning out the media beds1-2x per season, the beds serve as bio and mech filtration. So of the multiple systems you have running which do you find to be least demanding and most productive, including livestock?
@lynx-they also said they had toyed with taro root, if they are going for food for the multitude perhaps they should try rice. I think one of the reasons their methods seem to work well is because they control the outflow of info (pictures are only for personal use, not to be posted to social networking sites). Don't get me wrong, I think the message is there, but like Sylvia says does it turn morn people away when they try?

[Sylvia Bernstein]

Kobus, I beg to differ. Murray and I visited JT's Growing Power system together after the class that he taught in Denver and he expressed some of the same concerns about the design that I had. It is, I believe, about a 3" deep gravel bed topped with vermicompost, with another shallow bed on top for watering plants in pots filled with a soil mix with a capillary action. Great for growing watercress, and watering dirt filled pots, but my concern is that this is becoming the most visible face of aquaponics in the U.S. Plus there is the problem of very high (1:1) stocking density...

I don't know how this compares to Murray's new CHOP 2 design. He is still using flood and drain in 12" beds, but my understanding is that he has modified the plumbing to prevent solids build up in the sump tank. He has proposed modifications for filtering solids if you want to add on raft or NFT beds, and showed how to add a 2nd pump for redundancy. Not sure where the comparison is to Growing Power...

[TCLynx]

I agree Kobus, variety is great. Find what works for the particular goals of the system while also keeping the fish, plants and yourself happy. I'm also finding that certain growing methods may be more productive for me at different times of year too based on what grows well in my seasons.

[Sylvia Bernstein]

Hi David,

I've been to Growing Power as well, and wrote a blog post about my experience . I also did the interview for the cover story of the current issue of BYAP magazine on Rick Mueller, the guy who runs their AP systems. I think your observations are completely acurate. I would describe their system as a continuous flow shallow media bed system that is being optimized for maximum fish stocking density and not for the plants. JT Sawyer in here has built one of their systems, and my impression is he wasn't thrilled with it (he has since gone to standard 12" deep media beds, right JT?).

While is bordering on heresy to be critical of anything at Growing Power, I will say that I am concerned that they have become the most visible example of urban aquaponics in the U.S. Clearly their system works great for watercress, but could be much better designed for growing anything else...except maybe a lot of fish...and maybe that is just their goal. I worry, however, that people make the pilgrimage to Growing Power, see what they are doing, go home and emulate it, are disappointed, then walk away from aquaponics because "all it can grow is watercress". I also worry about those very high stocking densities. There is a non profit group in Denver that has set up a Growing Power style farm - even had Will Allen out to inaugurate it - and they just stocked their 300 gallon tank with 300 tilapia. Yikes. Hopefully they will be successful, but I'm afraid the more likely scenario is disaster. Rick has a long history in the aquatic industry - these people do not.

[TCLynx]

Hum, what to call a gravel bed with constant flow through like that. From back in my hydroponic days we called a trough of bed that had a constant flow through the bottom of it but that was filled with media a Modified NFT method. Not quite what they are doing with the water cress I know but by doing something like that you could grow plants that like it drier though you wouldn't be getting much filtration benefit from the media if only the very bottom of it were getting wet.

There are some other useful water plants though like water chestnuts that might be good to grow that way.

I know of a few AP set ups out there that run constant flood beds with a fairly high constant water turn over rate and they seem to be doing fine with both their trout and their veggies, when running constant flood one just needs to keep a closer eye on the water level and washing off the roots of transplants before putting them in and perhaps planting stuff a bit higher than normal if they don't like wet feet. I've got several beds running constant flood and other than the banana roots clogging things, they seem to be doing better than I expected.

Sorry I don't know too much about growing power's exact methods but it does seem to be working for them.