Richard bray

Dry Layer
Active Layer 8” - 9”
Sludge Layer
In order to accommodate these layers, a grow bed needs to be at lease 12” deep, but it's best to leave a few inches of empty space betwee® the top of the media and the top edge of the grow bed. Ideally, grow beds will be 14” deep.
The most common containers used for grow beds in media-fillec systems are:

• IBC totes
• Stock tanks
• Storage barrels/drums
• Household storage totes

Metal containers can leach chemicals into the water, and are unsuitable for any part of an aquaponic system. Wooden frames lined with pond liner are an option, although it works best if the frame is or. the ground to support the weight of the media.
As long as a container is at least 12" deep, inert, durable, and workable it is a candidate for a grow bed. If you have a readily-available supply
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of containers you want to use as grow beds, find the SPI code to see if they are food safe:

• 1 PET (Polyethylene Terephthalate)
• 2 HDPE (High-Density Polyethylene)
• 4 LDPE (Low-Density Polyethylene)
• 5 PP (Polypropylene)
• *7 PC (Polycarbonate)
• *7 uPVC (Unplasticized Polyvinyl Chloride)

The number "7" on an SPI code means other plastics, and includes many plastics that are not food safe.
If you will only have access to your grow bed from one side, limit the width of your bed to 28” or less. If you will be able to access both sides of your grow bed, limit the width to 4' so you can easily reach the Center from either side.
Fish and Fish Tanks
The fish in an aquaponic system serve one vital function:
• Digest fish food and excrete ammonia and solid waste
The waste from fish is what provides food for the bacteria—not plants—in your system. The bacteria will break down the waste into riant-soluble nutrients, which also cleans the water as it is returned back to the fish tank.
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The materials for a fish tank need to meet the same basic requirement as those for grow beds. However, while grow beds should be wide a relatively shallow, fish tanks should be deep with a relatively small diameter. This allows the water in the tank to resist major temperature fluctuations, which stress out the fish.
In a continuous flow system, water is constantly pumped from the thank through the grow beds, and back into the fish tank. This keeps the water at a consistent level, which lowers the stress level on the fish.
However, there are many drawbacks to a continuous flow system with media-filled beds, so most growers opt for a flood-and-drain system with a sump tank. A sump tank will collect water after it drains from the grow beds, and pump it back into the fish tank at an even rate.