Benefits of Vermiculite Growth Media for Separating Seedlings

Two of my aquaponics vegetable grow beds have a top layer of vermiculite.  I have detailed this in earlier postings. [Grow-beds-and-media-stackup.]

Some vegetables are very sensitive to root disturbance.  An example of this are pepper plants and specifically bell peppers.  Normally, to cover less than 100% germination, a gardener will plant 2 or more seeds (depending on expected germination rates) for every seedling desired.  When the seedlings are at their first true leaf you would cut off (kill) the less desired seedlings in a bunch to prevent disturbing the roots of the chosen seedling.

I found that vermiculite does not hold to the fine roots of seedlings. What I have been able to do then is to gently pull seedlings apart from the vermiculite and place them in another spot (making a hole for them with my finger).  The ones remaining do not get disturbed, and the transplanted one continues to grow also.  I did this first with tomatoe seedlings that had reached their first true leaf.  Tomatoes are hardy plants anyway.  But after that, I successfully did it with bell pepper seedlings.

This is a picture of seedlings in a bed of vermiculite. The red circled ones have been transplanted and doing fine after 3 days.  Note the coir pots for some of the seedlings.  These are meant to be transplanted into other beds. Since it is all soil-less I can even put them into the hydroton beds.

This is growth after 11 days total.  Note the transplants are doing fine. If you lift transplants when they are bigger, you need to be do it more slowly and gently as they have more rootlets developed.  I separated the two larger peppers on the left side just after taking this picture, and the one pulled successfully with vermiculite attached to its rootball.

Starting Seeds in Aquaponics Beds

Starting seeds for your aquaponics grow beds depends on the substrate you are using.  See this entry for options.  If you use vermiculite on the upper layer, you can just spread small seed on the surface and cover with a thin layer of more vermiculite.  Larger seeds can just be embedded in the vermiculite.  If you are using Hydroton, you can also embed larger seeds like beans just under the top layer.

For small seeds in Hydroton, or for more controlled planting in any media I prefer to use coconut husk pots with a vermiculite media.  I can germinate the seed either indoors or in the greenhouse, and then put the entire pot into the grow bed when ready.  This can be used in any media grow bed, including Hydroton.

The benefit of this technique is that you are not introducing organisms into your ecosystem that may be present in regular soil, you have control over the planting, and you can germinate the seed in optimum conditions for the appropriate seed.

Aquaponics:fouling water and other problems

Problems to be encountered in Aquaponics systems:
* predators: raccoons, opossums, they will eat your fish or destroy your grow beds looking for snails
    --> mechanically protect: cover fish tanks, enclose system
    --> simple styrofoam has shielded my system from these predators, though they did cut through my plastic door before I put foam on it also

* sludge fouling your piping and grow beds
    --> use a sludge separator: http://wolfenhawke.blogspot.com/2012/09/aquaponics-sludge-separator-update.html

* water fouled: this could be for any number of reasons, but most likely it will occur from overfeeding.  This can happen accidently due variations in an auto feeder
    --> turn off all feeding until water clears, don't worry, your fish can survive days without food
    --> if you see excess floating food, remove it
    --> if possible replace at least half of your water, but don't fret it if you cannot replace
    --> if you are using a timer on your water pump, bypass it so it is running 24/7
    --> run the system continuously until the water clears -- it will, then restart normal operation

* mysterious fishkill:  your fish are dying but the water is not cloudy
    --> this is rare for tilapia farming
    --> check your chemical levels
    --> check for dead fish fouling the water
    --> check the tank temperature -- sometimes heater elements will fail on
    --> check for water getting too cold -- temps lower than 55F are bad for Tilapia
    --> proceed similar to water fouled actions above: but on chemical imbalance, you will also need to investigate -- this could happen if you didn't "start the fish tank" and you put a lot of fish in at once, see http://wolfenhawke.blogspot.com/2012/10/starting-fish-tanks.html

 

Monitoring Aquaponic Grow Bed Water Levels

With ebb and flow water systems, it is useful to monitor your water level under the surface of your grow media.  This is a simple but effective method do that.

As you are filling media into your bed, put a length of 1.5" PVC pipe in the bed vertically in the media.  Allow the top to protrude above the media surface by a good 2 inches (5cm) at least.  If you are using fine media, it would be good to attach some fiberglass screening with plastic lock ties at the bottom of the pipe.

Now make the indicator using a straw and a piece of styrofoam that is smaller than the diameter of the PVC pipe.  Say about 1.5cm in width.

 Picture showing styrofoam with straw embedded.  Note the graduations marked on the straw.  This is long because I use deep grow beds in my setup.

Picture showing the level meter in operation.  Water filling the grow bed is causing the indicator to rise.

Salads with Ebb and Flow? YES!!

In aquaponics systems, salad greens are normally grown in a flow or flood system with the roots continuously in running water.  I have a deep bed ebb and flow system and recently populated one bed with mesclun salad mix seed.  I used the vermiculite bed for the salad greens.  Please see http://wolfenhawke.blogspot.com/2012/10/aquaponics-grow-beds-and-media-stackup.html for various media stackups.  Seeds were just spread on top of the fresh vermiculite.

The following picture is a successful yield offered by this method.

Bell Siphoning for Aquaponics Grow Beds

Aquaponics systems use one of two water recirculation systems primarily.  One method is the "flood system", "flow system", or "constant flow" system.  This system runs the water continuously through the root systems of vegetables.  The other method is the "flood and drain" or "ebb and flow" system.  This system adds water to grow beds causing the water level to rise to just below the media surface, and then drains the water and repeats the process continuously.

Flow systems are good for salad green farming.  Flood and Drain systems are good for all types of vegetables but are a little more complex.

As you have seen from my setup schematic, http://wolfenhawke.blogspot.com/2012/10/single-pump-aquaponics-system-design.html, I use Flood and Drain in my system.  This is accomplished by using a bell siphon in the grow bed.  This apparatus does not use energy but counts on vacuum created in a sealed water system.  There is plenty of information on building your bell siphon.  One paper is available here, http://www.ctahr.hawaii.edu/oc/freepubs/pdf/BIO-10.pdf.

Since my grow beds had a drain plug on the side, I used this. I do not recommend going from the side as the setup is more complex to tune, but I am showing this for interest/information.  Certainly, you can setup your similar beds with the draining straight down.

As you can see, my internal standpipe makes a 90 degree bend which is non-standard.















After that the bell pipe is installed on the standpipe.  Note, one disadvantage with the 90 degree standpipe connection, is that the bell pipe cannot seal as far to the bottom.  The top of the cut at the bottom of the bell pipe determines the minimum level of water in the grow bed.  My bed will have about two inches of water always at the bottom.

After this stage, you can fill the planter with your media.  As you can see, one benefit I do have with the 90 degree install, is that I can tune the height of the water draining by turning the bell pipe and standpipe as a unit.  I had to do this on all my planters to get the desired height -- this is likely because I do not use "snorkels" on my bell pipe and the trapped air is compressing and affecting the rising water level.

Single Pump Aquaponics System Design

I use an architecture in my aquaponics setup that requires a single pump per fish tank used.  This minimizes electricity and vastly reduces the complexity of the control system.  The water is pumped to my sludge separator design (see blog for details) which is at the highest location in the system.  Gravity is then used to move the water from the separator to the grow beds and back to the fish tank.  Using more than one fish tank in the same system requires balancing the effluent water from the grow beds and this will be addressed in another article.

The schematic of the setup is shown below:

The fish tank is shown below:

 













The sludge separator is shown here.  The pipe on the right is the influence. The pipe protruding from the front is the overflow back to the fish tank (a safety measure).











Here the piping is shown from the grow beds (3/4") to the collector (2") which returns the cleaned effluent back to the fish tank.

Since I use flood and drain as my water distribution, I could technically just keep the water pump running. I use drains on the side of the grow beds.  This side draining is much less efficient than bottom draining and what happens is that the water slows down in draining as it gets to the bottom of the bed.  This causes an equilibrium to be reached if the water pump is left on all the time.  At equilibrium the water is about 1/3 depth in the grow beds at all times.  I alleviate this problem, and save electricity to boot, by putting my water pump on a timer that runs 30minutes on, 30minutes off continuously.  This means I only pump half the time. It also allows the grow bed to get flooded and drain once per on/off cycle.

I have not had trouble with the side draining, but it does take a little tuning of the bell siphon.  We will cover this siphon design on another article.

Aquaponics Grow Beds and Media Stackup

Aquaponics is the raising of fish (for food) and recirculating the water through grow beds to grow vegetables (for food).  The ammonia that increases in the water in the fish tank is converted to nitrite and nitrate through the same process that occurs in a successfully operating fish tank.  In a display fish tank, this conversion occurs in the media in your filter and other areas (under the sand).  It is important to note that your fish tank filter's primary purpose is providing the media for the nitrogen cycle bacteria to thrive.  In aquaponics, this media is the material used to grow the vegetables.   The benefit of this is that the vegetation gets the nitrates they require directly as part of reducing the poisons in the fish water.  Thus you get a closed nitrogen cycle system.

On the post, Freeland-fp100-as-aquaponics-growbeds  I noted the Freeland bins that I use for my deep root grow beds.  On this post I will describe the stackup I use for the media.  The pictures below show a bed with hydroton as the top layer and one with vermiculite as the top layer.




The beds after being cut are 20" deep.  The bottom 6" are washed 3/4" gravel.  There is a long air stone buried in the bed at this point.  This is optional to have, but I wanted to inject air here to prevent any anaerobic bacterial action here.  A summary of the stackups I use is drawn below.

In some beds, I use Hydroton for the whole top layer (about 6" total depth).  In some I use about 4" of Hydroton and 4" of vermiculite.

The reason for the vermiculite is for seeding directly and for a variety of grow media depending on plant preferences.  Fine seeds work very well directly in the vermiculite.  I have had success with mixed salad green seeds, as well as tomato and cee gwa in the vermiculite.  I have had success with cee gwa directly in hydroton also.  In general for the hydroton beds, I start seeds in coconut husk pots filled with vermiculite.

The vermiculite really encourages robust root growth.  When harvesting often the top 3" of vermiculite is saturated with root (especially when growing tomatoe) and this must be disposed of and replaced with fresh material.  Below is a photo of vermiculite saturated with tomato root.  Also is a photo of cee gwa roots that were grown in hydroton.

Salad growing in a vermiculite bed:

Night Fennel harvest

I learned from UC-Davis that Fennel root grows well in California.  I planted this from seed in the greenhouse over the winter.  This is the second harvest of my roots.  This done at night while I was cooking some curry.  The root can be cut into 1" slices and baked with olive oil and balsamic vinegar. The stalks can be cut and used like a feathery celery.  I cut stalks up to 1cm lengths and put half of one roots worth in to a curry. The baked roots are delicious and all the parts have a slight anise flavor.

Freeland FP100 as Aquaponics Growbeds

I use Freeland FP100's for my growbeds.  I run deep grow beds.  That is, at least 12" grow depth for the plants.  This is not usual, but I found from my normal growing that plants do a lot better with deep roots.

I recommend the FP60 for those who are interested in this design. I just happen to get the FP100's at a good price.  As you see though, I effectively cut them down to FP60 size.

This is the starting point:

A nice unit.  Made in the USA. http://www.freelandind.com/fipolytanks.htm

Next I cut the top off using a sawsall.

Don't these look like very nice garden bed separators?  Good recycling use.  That's another post.

Note, the FP100 has a drain pre-plumbed.  This is re-usable, but the internal fitting is aluminum. This needs to be replaced with a 1" FT to 1" SLIP adaptor.  The FT portion just replaces the aluminum threaded fitting.  Put teflon tape on the plastic thread prior to putting the FP adaptor on to prevent slow drip leaks.

This is a picture of a completed grow bed.  It is filled with a hydroton mixture.  Due to the pre-fit drain, this setup is configured to drain from the bottom side.  Normally beds are made to drain down.  This works without tuning, but what happens is that the drain is not at a consistent speed. The drain starts quickly then slows down for the last third of the level.  It takes about 10 minutes to fully drain the bed.

You can see the overflow on the top left of this bed.  This is made with 1" hose and uniseal fittings. http://www.aussieglobe.com/uniseal3.htm
The small hose is for air being pumped into the bottom of the bed.

I will post the siphon design for this bed and also the media layers I use in future posts.

Cheers.