Friday, April 15, 2011

Early Season Update

First, an update on my sand-based system. I noticed today that the water was collecting on the surface of the sand more than usual. Turns out that an algal mat is forming, and as a result, the water was having a hard time permeating into the sand. This is to be expected, and it's not a big deal. In fact, I think the algae will play an important role in the nutrient cycle for the plants I'm trying to grow. Problem was easily remedied by poking a few holes in the sand using a piece of 1/2" PVC pipe.  I imagine I'll have to do that regularly. Luckily, I planned ahead for something like this, and created channels in the sand around the outside of the grow beds for the water to move through. Since I don't plan on planting anything in these channels, I'm not interfering at all with any of my plants by poking holes into the sand.

My pond-based system is cranking along nicely. I'm in full swing in terms of spring veggies. See photos below. I'm particularly excited about the strawberries. They look fantastic, and there look to be a record number of berries on the way. I thought of a new term today for my system: "aquapondics". You heard it here first!

Cilantro in rear (left), arugula in rear (right), spinach in middle, and broccolini on left/right front

Strawberry grow bed. This grow bed is devoted entirely to strawberries, and they survive year-round (even when the entire grow bed froze solid with ice this past year)

Two tomato seedlings just planted on left, spinach in the middle, broccoli on right (with some leftover cilantro growing up in the spinach)

Pond with grow beds in the background


AquaMonster said...

Are those growbeds filled with sand all the way?
Why? I cannot think of one good reason to use sand instead of gravel or something else (other than to try it just to see) I once tried aquarium gravel and it became horribly clogged up in a few weeks. (Whereas there are people with 3/4" gravel growbeds that have been running 4 years without incident..) How long has the sand been going, and how has it worked for you? Beware the algae growth could turn into a big slimy problem! - I am afraid the poking of holes may only help in the short term, and later you could have a problem..

Brian Naess said...

Why sand? Well, Dr. Mark McMurtry who basically invented what we now call aquaponics used sand and is a big proponent of sand as the ultimate media. He says that sand has exponentially greater surface area for the beneficial bacteria to bond to, and I believe that - it makes sense. If that's true, then it stands to reason that a sand-based system will filter the fish waste better. I'm hoping it means I won't have to filter the water as often, as each time it passes through, it comes out completely clean. If that's true, then it stands to reason that you could save money on electricity with a smaller pump. Sand is certainly a lot cheaper than hydroton, and it's a ton easier on the hands than gravel.

But, if I'm honest, I'm trying just because I want to see if it works. No one else is doing it, and everyone says it won't work. Maybe they're right, or maybe their wrong. I'm the kind of person who needs to find these things out for himself.

Dr. McMurtry said that the algal colony will form a mat initially, but will then die off. This will act to release all of the nutrients that the algae have taken in and act as an additional nutrient source.

There is a 2" layer of small river gravel on the bottom, with sand on top, so no, the sand doesn't go all the way to the top.

I've been running my gravel/hydroton system for 3-4 years now without cleaning it out once, so I know what it can do. I was looking for a different sort of challenge. If it doesn't work, then it's not a big deal to dump the sand out and throw some gravel in and crank it up again. If it does work, then maybe I'll find out that it is superior than gravel or hydroton or any other media, which is what someone who devoted their entire Ph.D. work to aquaponics has claimed.

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