I have been wanting to build a system with 50/50 media bed/floating raft for ages, I've got most of the design plan figured out, just gotta build it.
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| What raft systems can grow vs our gravel beds. http://byap.backyardmagazines.com/forum/viewtopic.php?f=1&t=4815 |
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| Author: | DanDMan [ Jan 21st, '09, 02:08 ] |
| Post subject: | What raft systems can grow vs our gravel beds. |
I was looking at a UVI short course pdf and they claim to get 11,000 pounds of fish in a 4 tank (~28,000 gallons of tank). At this rate I should be able to from 360 pound of fish in 1000 gallons. Anyway, what I noticed is that they are growing the following in their raft system: Tomatoes Okra Zucchini Squash Basil Lettuce Watercress Chives Chamomile Squash Parsley Cantaloupes (rock melon) Zinnia Now that pretty much seems to be what grows well in our flood and drain systems. Im sure corn would have grown also but its hard to place that in a raft. They have a solids removal filter followed by a bio filter. Now I have to question whether or not I should not try a large raft system. My next grow bed will hold 17 cubic yards of gravel (13 cubic meters). The less gravel I have to buy wash and haul the better! Perhaps I could have half of it in a flood and drain grow bed and the other half in a raft system. Have any of you had first hand experience with the University of Virgin island's systems? Their bio filter seem to be very small compared to our grow bed bio filters. Does anyone have any more information on how their bio filter and clarifier is constructed? I have a blower already so I could get lost of bubbles into the system. Thoughts? Comments? Morning Star Fishermen sell a similar system that separates solids and has a bio filter with half the volume of the fish tank. I already have almost 1200 gallons of gravel so if that can provide enough bio filtration than I need not even add more gravel to the system when I add another 1000 gallons of fish tank. |
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| Author: | Dave Donley [ Jan 21st, '09, 06:19 ] |
| Post subject: | Re: What raft systems can grow vs our gravel beds. |
I am interested to see a flood and drain bed followed by a raft bed. What ratio gravel bed to raft bed? not sure... |
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| Author: | earthbound [ Jan 21st, '09, 19:46 ] |
| Post subject: | Re: What raft systems can grow vs our gravel beds. |
I have been wanting to build a system with 50/50 media bed/floating raft for ages, I've got most of the design plan figured out, just gotta build it.
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| Author: | Jensilaedi [ Jan 21st, '09, 20:57 ] |
| Post subject: | Re: What raft systems can grow vs our gravel beds. |
so what's your main barrier EB? |
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| Author: | DanDMan [ Jan 21st, '09, 22:25 ] |
| Post subject: | Re: What raft systems can grow vs our gravel beds. |
I noticed that the filter to water ratio of the morning star fishermen's small systems is 1 gallon fish tank to .5 gallon biofilter. I guess they are using bird netting for the biofilter / fine solids filter. Of course a packed in net is going to have a lot more bio active surface area than expanded clay or gravel. EB I would be interested in hearing what what you think the minimum ratio needs to be. I guess part of that depends on how much if any of the solids you remove before you filter it. It seems to me that if their system can grow fruiting veggies without much mineralization going on then perhaps a simple swirl filter to remove most, but not all, of the solids might be a better way to go. Also, worth noting is the fact that they use a net pot with compost to grow the plant in. The compost may be providing some measure of trace elements or minerals. |
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| Author: | earthbound [ Jan 22nd, '09, 19:54 ] |
| Post subject: | Re: What raft systems can grow vs our gravel beds. |
I'm not planning on removing any solids. Just pumping into the first two growbeds which will act as solids removal/biofilter, then out of them into the floating raft which will be two beds. UVI had problems with fruiting plants and found that they had to leave their solids in the system to a greater extent when growing fruiting plants. Main barrier for me? Time and space.. Would like to do it here at the shop, but then we have to be careful about having experimental stuff set up. No sooner do you set up an experiment of some sort and people say "Oh I like that, how much is that?". We want to test things thoroughly before hand and there's always the chance that it won't work well, but I doubt it... |
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| Author: | Food&Fish [ Jan 22nd, '09, 20:39 ] |
| Post subject: | Re: What raft systems can grow vs our gravel beds. |
We want to test things thoroughly before hand and there's always the chance that it won't work well, but I doubt it... dont go down that road just keep doing it till it does |
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