Day 8: Growing Raft

The most common commercial growing system for aquaponics is the raft method.  So, of course, it would be silly for me not to give it a go.

The only major problem I have with this method is that the current 'norm' for this process is using rockwool as the growing media for each plant 'pod' in the raft.  Rockwoll is made by heating rocks such as basalt and chalk and actually making a wool-like mat.  I'm concerned about the way these rocks are mined, and about the sustainability of such a product.  Also, I have read that rockwool can pose a problem in that it must be pH buffered before use.  Again, this usually requires chemicals.  Eventually, I intend to look into coir (recycled coconut husks) for this instead of the rockwool.  But, for now, I don't have any coir so I am using plain old polyester fiber fill.

 

I actually find this to be a great inexpensive filter media (though I realize it's probably not the most sustainable material that ever existed, either).

The raft itself is simply a piece of styrofoam cut to fit the water chamber with circular holes cut in it for each plant.  These styrofoam rafts should be able to be reused for years to come.   

The plants were transfered to the raft on day 8.  About 3 of the plants shriveled and died.  I later determined this was because the roots did not reach the flowing water below.  The polyester fiber fill does a great job of holding the plants in place, but there is not enough in each cell to really be able to wick much moisture up to the plant.  By 14 days, I found the root systems were much larger and far more viable for transfer to the rafts.

 

Day 4: Holy Moses!

According to the package, these lettuce seeds have a germination time of 7 to 14 days. 

I don't know how accurate that estimate is, but in this system I have seen germination of these seeds in 3 to 4 days.  Cool!

Just look at all that root growth in the matter of a day!

The lettuce seeds (both varieties) are the only seeds that have germinated.  Many of the basil seeds appear to be getting almost moldy.  I'm unsure as to whether this will cause them not to germinate, or if it is just a deceiving appearance.  Time will tell.

Day 3: Lettuce Germination

Horray!  I spotted some tiny lettuce sprouts on Wednesday morning!

They're tiny, but if you look closely you'll be able to spot them!

Assembly - Complete

Finally, my aquaponics system is built and partially set up.

The frame is wood.  I decided this would not only be less expensive to construct (than to buy a metal shelving unit), but also easier to set up exactly how I wanted it.

There are 4 water chambers within the unit.  The top receives the water pumped from the fish tank, and the lower 3 units are gravity fed with drains and pipes. 

The bottom chamber drains back into the fish tank by gravity as well.

(the water is cloudy from the addition of the gravel media - it was cleared up by the filters in 12hrs)

 

There is currently nothing in the top chamber.  I may eventually hang lights from the ceiling to operate this chamber as a growing chamber, but right now I don't have enough fish to make this necessary.  At this point, I intend to add bio balls to the top chamber to utilize it soley as a biological filter.

The second chamber is a gravel media growing chamber.  It has been planted with two varieties of lettuce and various herbs.  These seeds were all sewn on 10/11/09.

Sewing seeds has definitely been a learning experience.  Because the water line must be very close to the top surface of the gravel, even very slight adjustments in water flow can cause the seed to be washed away.  It is likely the lettuce seed that was sewn closest to the in-flow side of the chamber has been spread throughout the gravel media.  I will definitely work on developing a better seed sewing procedure.

The third chamber will be set up to be a gravel media growing chamber.  Because the gravel was so dirty, even after cleaning, the third chamber currently serves as a filter.  I do intend to plant this chamber after I have partially grown out the second chamber to get an idea of new techniques to try (the filter floss on the left will likely eventually be replaced with gravel media).

Only the second and third chambers are currently supplied with grow lights.  The fourth chamber will also have lights before it is seeded.

The fourth chamber will likely be used for a raft growing system.  Currently I am searching for a sustainable alternative to rock wool to start the seed in.  I am also researching good materials for the actual construction of the raft.  (I am considering insulation board)  Until the raft is constructed, the fourth chamber will be utilized solely as a filter.   

Field Trip: Growing Power

On Saturday, September 5, my Dad and I went to the Growing Power greenhouses in Milwaukee. They have a tour every day at 1:00, and we thought it would be a good weekend to go since everybody else was headed "up north" for the holiday weekend.

Growing Power does lots of cool stuff at their greenhouses. You should check out their website if you're interested. (link on the left)

I'm mostly interested in their aquaponics system. There are plenty of things I would choose to do differently, but just by seeing their system I learned a lot.

Here's how their system works:

The 'tank' is 4-5' deep, and is dug right into the floor of the greenhouse. then lined with a membrane much like a pond liner.

That white container suspended over the tank is an automatic fish feeder.

Thousands of fish live in this tank. This is where the 'aqua' part of aquaponics comes from.

These are Perch in this tank

Plants have no use for ammonia, and at high enough levels it is very toxic for fish, too. So, if you don't have a nice colony of good bacteria in your system, and you pack your tank full of fish - you're just facilitating a fish massacre. I think this is probably the number one thing people mess up with raising fish. It's BIOLOGY, people! Embrace it!

Here is a lovely diagram showing how the toxic ammonia is converted to nitrogen. This is why supplying a nice place for the 'good bacteria' to live is so important in an aquatic environment.

Once the ammonium has been converted to nitrates, it becomes VERY useful to plants. This is where the 'ponics' part of aquaponics comes in. Using that nitrogen rich water, you can grow plants hydroponically.

The water from the tank is pumped through pipes up to the growing beds above it.

Then, by gravity, the water travels all the way to the other end of the bed.

At Growing Power, the growing beds run the full lenth of the tank, which runs almost the full length of the greenhouse. I highly doubt this is the way I would do thing if it were my system, but it seems to work for them.

Once the water reaches the other end of the bed, it is drained back into the tank.

This tank is prepared for Tilapia. They are vegetarian fish, so they like to eat the duckweed that is floating on the top.

Growing Power also does a lot of vermicomposting. Here is one of their outdoor composting piles. They use this pile for 'worm breeding' though I'm not entirely sure why that would be necessary. Either way, it's a nice compost pile.

Here are some of their vermicompost bins inside the greenhouse. Again, not so sure that's how I would do it, but if it's working for them that's great.

They also harvest honey.
Dad says he wants to do this. I think that's great - I'll be happy to eat some of his honey.

Here's another part that gets me all excited.
They have chickens, ducks, and goats. I want me some chickens! I'm still pondering goats, sheep, etc. I think sheep would be a great route as far as my interest in herding dogs goes.

Help me, Rhonda! Look at these adorable babies.

They can keep over 100 chickens in one end of a hoop house. Chickens also generate lots of heat, which is great for winter heating of the hoop house.

Yay for fresh eggs! Growing Power produces 20 dozen a day.