Add nutes until mature?

[Daniel Gunloche]

Hello all,

I am in the process of converting my Hydroponic system to AP.  I am planning on cycling the AP system separately (fishless) for a while.  But I understand it will still take over a year for the AP system to mature to full effectiveness.  Why have I never heard of anyone taking TDS readings and simply supplementing the system with organic hydro nutes to maintain the desired TDS readings?  I would think it would not be harmful to the fish if the system will eventually get to that level in a year or so anyway.  And could organic nutes be added to a mature system every year to raise the TDS in winter for tomato production?  Is there a maximum TDS level that the fish can handle? And if so, what would it be?  And would it be taboo to add small amounts of chemical hydro nutes to an AP system until it matures?

Thanks

Dan

[Daniel Gunloche]

Man, You guys are the bomb!!!  (I think that is good right?)

As far as 0.5:1 or 1:1 - I guess what I am saying is the minimum media bed ratio needed to make the system effective, and the effluent goes to nft or the rafts.

As far as "cranking" the channels it would be a matter of pushing a button at the end of the isle.  It would simply (Ha) run a common winch motor (more like three, one on each end of the channels and maybe one center),  The winch would operate a common cable running perpendicular to the channels.  The channel to be shifted would just engage to that cable(s) and be drawn over, the winch would automatically switch off on load when the channel base hits the stop on the one next to it.  My thinking is weight, if the channels where movable, it would be good if they don't weigh a few tons each.  So daily rounds - which is what I do now, would just involve moving each channel over by holding the button for 15-30 seconds or so.  The overhead vine suspension and wrapping down the vines could all be contained within each channel-rack probably as easily as any other method.   

What I am doing right now is I have my tomatoes planted 12" on center in channels, My suspension above has two overhead rails running parallel to each channel, one rail 12” either side of the channel (therefore 24” apart from each other).  So the plants are hung alternating zigzag to either side, making them physically 24” apart lengthwise and 24” apart along the length of the rail they are hung on.  Then next to this rack of course is an isle, then another identical rack etc..  So the idea is to make these entire racks shiftable.. Right now my channels are a sort of hybrid 6” PVC pipe that is level, bare root like NFT but I flood and drain on a timer because I have already dealt with anaerobic zones and damming when I was doing NFT.  My NFT got to the point that my plants liked it much better when I cycled the nft flow off, then flushed at about 3 gpm, then drained off again.  But I like the idea of this system now completely flooding and draining.  It seems to be working well, but I am concerned about root space in the long term. I do have about 1.5” of pea gravel in the bottom of these channels to keep the roots from getting too soggy on the bottom, I know the roots will grow thru it, but think it may still help.  I have a ¾” pvc line running directly below this channel and the ¾” tees up into the channel every four feet, and that is what floods and drains the channel since it is level, and I flood it to about 1” from the top. I cut a 3” wide slot lengthwise out of the top of the channel pipe, then took the removed portion and glued another 4” wide piece of thin-wall pipe to the top of it to make a cap that locks into the slot in the channel (does that make sense?) then I cut these into 10” lengths to place between each plant.  So I have full access to the plant roots for whatever reason.

 

Thanks a ton

Dan

TCLynx said:

I'm confused about what you mean on the ratio for NFT or Raft being 1:1 or 0.5:1?????  For a pure media based system the 2:1 grow bed to fish tank works very well.  To find out if lessor amounts of media work long term while heavily loaded to replace the swirl filters and stuff you should probably ask Chris Smith, unfortunately he has only started changing his systems over to that in the past year or so and I can't say that there are many systems out there running media beds as the solids filters for their raft/NFT systems long term yet.  I know some people who have done it on small scale backyard systems but I don't know how long they have been running nor how heavy the fish loads are.  Anyway, it is still a new method so we are still learning.

 

Deep beds, I love my 24" deep beds cause I do get plenty of filtration while also having beds at a nice working height without having to spend money building stands sturdy enough to support heavy gravel and water.   What about 36 inch deep beds?  Well you might ask OutbackOzzy over on BYAP, he is building a commercial system for trout and his grow beds are full size IBC's.  Again that system is still under construction so it's hard to say what will happen 7 years from now but his old home system had some full IBC grow beds in operation for at least a couple years and seemed ok.

 

Media beds are still a great way to grow plants and I know of some plants that will clog beds with roots but I cope with that by having seasons so I am not growing the same plants year round in the beds so in the off season the worms can break down the excessive roots of the aggressive plants.

 

Now I'm not quite sure how you will provide enough space for big indeterminate plants while moving them back and forth to have isle ways and still be able to wrap down the vines as they grow.  I expect it is possible to do but remember that air flow is important to tomatoes so if you have plants spaced really close to the point of touching each other you will be at great risk of certain diseases and pests really doing you some major damage.  Also, plants that close together, you will need to be out there cranking the aisle over and walking down each aisle and tending/pruning the plants every day to keep the plants from wrapping leaves around each other and making it very damaging to open the aisles if you put it off.  While I understand that space in a greenhouse is at a premium, I have also learned that if it is not really easy to access parts of your garden, you will not go there and do the tending needed to make it productive enough to warrant the premium space.  Make it easy to access the plants.

I don't know how one would to that kind of method for DWC unless your troughs are of a material where you could put on waders and walk in the water without worry of damaging the liner.  You could float rafts back and forth a bit to create a space to walk between.  I don't think you could move the rafts far because the plants are attached overhead so it isn't like you could float them all over the place.  The rafts lend themselves better to smaller plants that are quick and you can plant a whole raft at one end and float it along and harvest at the other end.  I have seen big greenhouses where the entire floor is a big raft bed and the rafts are placed in on one end and floated along as rafts are harvested out of the other end.  There is enough play so that workers can push rafts apart to walk in and tend rafts in the middle but with the smaller plants there isn't as much daily tending.

 

For rafts, the beds/troughs are usually build on the ground with liner and so they could be just about any size depending on the type of liner used but most of the time they base the size on the convenient sizes to cut the 4x8 foot foam to avoid waste and also appropriate width to use the liner of choice most efficiently.  I've done a raft bed around 34 inches wide so I cut the 4x8 foam into a 4' by 32 inch pieces or into thirds.  Most others do 4' wide raft beds when using liner that comes in 6' wide rolls or if you are using liner in a 10 foot wide roll you could to an 8' wide raft bed.

[TCLynx]

Well if that winch method works well for Hydroponics with your channels, then it should work well enough being fed "clean" aquaponic water too.

 

As to what the minimum ration on the media beds to keep the water quality good and not have issues with the beds going anaerobic well if you find you didn't do enough beds, just make sure you have space to install more should you find you need them.  If you are not growing any plants in the beds then it should be reasonable if not easy to do a clean out of them every so often.

[Daniel Gunloche]

To clarify - the hydro system is built - but not the winch system.

Thanks

Dan

TCLynx said:

Well if that winch method works well for Hydroponics with your channels, then it should work well enough being fed "clean" aquaponic water too.

 

As to what the minimum ration on the media beds to keep the water quality good and not have issues with the beds going anaerobic well if you find you didn't do enough beds, just make sure you have space to install more should you find you need them.  If you are not growing any plants in the beds then it should be reasonable if not easy to do a clean out of them every so often.

[Vlad Jovanovic]

Hello Daniel, 

I know that some people are doing well with 20% to 30% media beds sq. footage to their total DWC raft sq. footage, but this is with low fish stocking densities and Friendly's style rafts (4' wide by 12" deep,  though I don't see that the raft style would make much of a difference). This is growing light feeders like lettuce and leafy greens though.Like TC said you could always add more media beds. Or a swirl filter if your stocking densities are high and you run out of room for more media beds. Here's a real good DIY how to vid for an aquaponic swirl filter...   http://www.youtube.com/watch?v=39xT5xzNu3s

You could then feed your worms the muck that you empty from the swirl filter if you don't want to lose those nutes.

[Vlad Jovanovic]

Your original post has just now spurred me to test the water in my little "hydro" set up. I have plants that are 24 days old 16 days old and 7 days old. They are all doing way better than I expected. They are in 2" net pots filled with hydroton, and sit DWC raft style in polystyrene sheet with the holes cut out.  12 liters of water in a plastic tub with 2 air stones and a ladies nylon filled with about 70 grams of worm castings. The light from 2 38 Watt T8's is all they get.

 

Ammonia 0

Nitrite 0

Nitrate <50 but >100

pH 8.7

 

I don't know what else is in there as I have no way to test for it (potassium, phosphates, calcium magnesium etc)..., but again they are doing really really well. And as a "supplemental nutrient"  it wouldn't seem like it would tax the fish at all?

The plants are some habenjero pepper sprouts some romaine lettuce and some kale.