newbi needs info

[ray fox]

ok some background info my partner and i have a small 20 person csa in central ny,usa we are going to to expanding the size of our farm and are also considering adding an ap system to the setup.

so my question is can anyone tell my the diference between gb`s and dwc`s as far as the plant spaceing is concerned?

[TCLynx]

In a media filled grow bed, you can space the plants however you want, it's a lot more like planting in a garden bed.

 

In a DWC raft bed, the spacing is decided when you make the rafts so you are limited by how you make the rafts.

 

What spacing you Should use for different types of plants is dictated more by the plants than by the method you use to grow them.

[ray fox]

thanks for getting back to me.so if im understanding correctly then then only diference is really the ease of planting ad harvest as far as the plants are concerned

TCLynx said:

In a media filled grow bed, you can space the plants however you want, it's a lot more like planting in a garden bed.

 

In a DWC raft bed, the spacing is decided when you make the rafts so you are limited by how you make the rafts.

 

What spacing you Should use for different types of plants is dictated more by the plants than by the method you use to grow them.

[TCLynx]

Rafts are especially good for planting lots of the same compact thing all at the same time and then harvesting them all at the same time since you can lift out a whole raft and set it up at a harvest or planting station and people can work in relative comfort.

 

Media beds are going to be better suited to longer term crops that you might harvest from the same plants for an extended period of time.  If the beds are on the ground though you have to bend for planting or for harvesting small plants but this would be well suited to say growing vines like tomatoes and cucumbers.  If a media bed is built up at waist high though there will be conciderable extra cost in the structure to support water and media up off the ground though to many people the extra cost is worth it for a no bend garden.

 

Now pure raft systems require additional filtration and or cleaning, but they are far more portable if that is of concern.  Gravel is much harder to move from place to place while the water can simply be pumped and the other elements are relatively light.  However media based systems if designed right can use less fish to get more plants since the solids are retained and slowly become nutrients in the media beds while pure raft systems generally have settling tanks and net tanks that have to be cleaned out which looses those extra minerals when the solids are removed.  Now I know there are systems out there that break these rules but most of those seem to be exceptions.  There is also a growing movement to mixed systems that will use media beds to filter the water before sending it to the raft beds but that method is still new so we don't yet have much in the way of hard numbers about how much media bed is needed per some amount of fish and raft in order to avoid ever needed to "wash the gravel again" and I'm sure even once there are several years of experience on this, it will vary from situation to situation depending on the particular worm population and various other factors.

 

Have I totally messed up your design yet and sent you running back to the drawing board?  Probably better now rather than after you have already built everything.

[ray fox]

lol tc actually you have helped me a great deal most of my problem was try to figure out the size of my system acording to my csa orders and some small wholesale orders thats why i needed to know about spaceing. thanks again for all your help and there no such thing as to much info

TCLynx said:

Rafts are especially good for planting lots of the same compact thing all at the same time and then harvesting them all at the same time since you can lift out a whole raft and set it up at a harvest or planting station and people can work in relative comfort.

 

Media beds are going to be better suited to longer term crops that you might harvest from the same plants for an extended period of time.  If the beds are on the ground though you have to bend for planting or for harvesting small plants but this would be well suited to say growing vines like tomatoes and cucumbers.  If a media bed is built up at waist high though there will be conciderable extra cost in the structure to support water and media up off the ground though to many people the extra cost is worth it for a no bend garden.

 

Now pure raft systems require additional filtration and or cleaning, but they are far more portable if that is of concern.  Gravel is much harder to move from place to place while the water can simply be pumped and the other elements are relatively light.  However media based systems if designed right can use less fish to get more plants since the solids are retained and slowly become nutrients in the media beds while pure raft systems generally have settling tanks and net tanks that have to be cleaned out which looses those extra minerals when the solids are removed.  Now I know there are systems out there that break these rules but most of those seem to be exceptions.  There is also a growing movement to mixed systems that will use media beds to filter the water before sending it to the raft beds but that method is still new so we don't yet have much in the way of hard numbers about how much media bed is needed per some amount of fish and raft in order to avoid ever needed to "wash the gravel again" and I'm sure even once there are several years of experience on this, it will vary from situation to situation depending on the particular worm population and various other factors.

 

Have I totally messed up your design yet and sent you running back to the drawing board?  Probably better now rather than after you have already built everything.

[TCLynx]

Ah, well yes the planning for commercial scale it quite a challenge that I'm only just learning.

 

You might want to pick the brains of Gina from Green Acres and Chris Smith since they are both doing combo media and raft commercial operations.

[ray fox]

tc thank you once  again and ill be sure to contact them.i do appologize for not getting back to you sooner your help has been great im glad i found such a great site

 
TCLynx said:

Ah, well yes the planning for commercial scale it quite a challenge that I'm only just learning.

 

You might want to pick the brains of Gina from Green Acres and Chris Smith since they are both doing combo media and raft commercial operations.

[RupertofOZ]

Spacing on raft systems is essentially the same as those used in NFT hydroponics... primarily because they're growing similar crops...

Larger vegetables would require some variation in spacings... but most larger crops probably present potential problems of weight and/or stability in raft systems... unless factored into the sizing of the raft boards...

[RupertofOZ]

The limiting factor of "hybrid" systems will be the sizing of the media beds... as they are the principle filtration method for the system.... stocking densities should be calculated to the filtration capacity of the beds alone...

There will be some additional filtration capacity associated with the raft beds... but limited in respect to the media beds... just view it as a bonus...

 TCLynx said:

There is also a growing movement to mixed systems that will use media beds to filter the water before sending it to the raft beds but that method is still new so we don't yet have much in the way of hard numbers about how much media bed is needed per some amount of fish and raft in order to avoid ever needed to "wash the gravel again" and I'm sure even once there are several years of experience on this, it will vary from situation to situation depending on the particular worm population and various other factors.