Aquaponics-Building a 3 stage filter

In moving forward in our aquaponics adventure in the greenhouse, my next step was to build a constant height system vs the fill & drain systems (See previous post for explanation of each) that I had previously built. One issue which presented itself was that an additional piece

3-stage filter
3-stage filter

would have to be added-some kind of filtration system, since the constant height grow bed has no grow media-only water. with foam rafts. Putting the brain to work, I came up with a plan to build an inexpensive 3-stage filter.

The first stage  would have to remove solid waste, followed by a second stage to remove smaller impurities. The third stage was the most important, being that it would not only filter but grow necessary bacteria to return to the fish, known as a bio-filter.

3 stage filter-water inlet installed with uni-seal
3 stage filter-water inlet installed with uni-seal

I started with a 5 gallon bucket.  The

3 stage filter-uni-seal for water inlet
3 stage filter-uni-seal for water inlet

bottom of the bucket would serve as a swirl filter for solid’s extraction, which would need a water inlet near the bottom. Drilling a hole and using a uni-seal for 1/2″ PVC, I inserted an inlet pipe, adding a 1/2″ 90 inside to promote the swirl in the bucket base.

3 stage filter-hardware cloth cut into large "X"
3 stage filter-hardware cloth cut into large “X”

From here, I would need something very sturdy to keep the base of the bucket open-for swirl process, yet be able to hold the weight of the foam and bio-filter: enter hardware cloth. The hardware cloth would add enough stability in the base of the bucket to support the weight of the next two stages. I cut the hardware cloth into a large “X” leaving a circle in the center the

3 stage filter-Hardware cloth table for inside bottom of bucket.
3 stage filter-Hardware cloth table for inside bottom of bucket.

same size as the internal dimension of the

Cut a gap in one of the corners to accommodate inlet pipe.
Cut a gap in one of the corners to accommodate inlet pipe.

bucket. I then folded the legs of the “X” to make a table of about 4″ high, which would fit down tightly inside of bucket.

Swirl section of 3-stage filter
Swirl section of 3-stage filter

This was the hardest section to do, working with the hardware cloth. The next step would be the foam filter, which would be as simple as cutting a round piece of foam to fit tightly inside bucket on top of table.

3 stage filter foam cut
3 stage filter foam cut
3 stage filter foam inserted
3 stage filter foam inserted
3 stage filter bio-media
3 stage filter bio-media

 

 

 

 

Once the foam was in place, it was simply a matter of rinsing my bio-media and adding about a 6″ layer on top of the foam filter. This completed the 3 stages of the filter, which left me with only a way to pump the filtered water back into the grow bed.

My initial thought was to use a gamma-seal lid and pressurize the filter from the pump so it would flow from the lid of the bucket back to the tank. Unfortunately, even a gamma-seal could not hold the pressure and leaked horribly.  I mean this as no detriment to gamma-seal’s as they are great for food storage etc, but just could not maintain a seal under pressure.

So rethinking, I just added a 1″ drain through the top portion of the bucket and positioned the bucket so it could just flow back into the grow bed.

3 stage filter with gamma-seal did not work
3 stage filter with gamma-seal did not work
3-stage filter as hooked to my constant height aquaponics tank.
3-stage filter as hooked to my constant height aquaponics tank.

 

The filter has been hooked up now for a full day and seems to run just fine. I will be adding some gold fish to the system today to start getting the ammonia and ph balance right before I add my tilapia fish next week.

UPDATE: Adding an auto-clean to the filter.

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