DIY Zakki Sieve

[gmessler]

Has anyone done a DIY Zakki build?

Here's one....

[Grumpy]

If you use "advanced search" on the right near the banner of this page, and search "diy sieve" you will have several hits. In the past, folks had difficulty finding a source of wedge wire screen material.

[gmessler]

Thanks Grumpy. I tried that and it doesn't appear to be any "zakki" style sieves.

Well...Here's the first DIY "Zakki" build.

[gmessler]

So a little backstory to explain why I built this.

Two years ago I found a couple of EA pond sieves for sale at a great price. They weren't the Cetus but a cross between the Cetus and an Aquaforte Ultrasieve 3. I had a difficult time getting any information on the units and Evolution Aqua ghosted both my phone calls and emails to get any information on specs or replacement belows / parts.

Because I was feeding two units with 3 water sources I built a 100 gallon collection tank that my two bottom drains and the skimmer would feed into. The tank would also serve as a safety net allowing the pond level to only drop 17" before the outputs to the sieves sucked air.

Unfortunately with both units tied together they wouldn't supply a 6200 GPH pump without sucking them dry.
I decided to lower the units 4" below their "pond level" lines. This meant that when the pumps turned off the water would overflow the units so I built up the sides an additional 5". To my disappointment they still couldn't supply the water flow that I needed. The issue looked to be more about flow to the units but I believe the units had their own issues as well.

Last year I decided to make an attempt at my own "zakki" sieve however after purchasing the pipes my personal life got a little crazy and I had to put off the build until this year.

Here's my build......

[gmessler]

I set out hunting for 24" sewer pipes. I was surprised how many were out there and available at a reasonable cost.
I found these two for a total cost of $200. I do intend on building a second unit, likely this year.

Later I found a 36" tall blue one when construction crews were redoing the water/sewer lines in a neighboring community.
They let me have it for free.

[gmessler]

My next step was to source 3/4" solid PVC sheet for the bottom. I was shocked at how expensive it was. Over $500 for a 4'x4' piece
Because my pipes were long enough I decided to try my hand at creating my own flat stock from the pipe.
I first cut about 27" of pipe off then measured 27" of circumference and cut that.
Here's what I ended up with.

[gmessler]

The next step was to build a makeshift oven. I used some scrap 3/4" plywood I had laying around.
I made it 12" tall and 36"x36". I cut a hole in the one end for my propane heater.
Knowing that the fumes from PVC can be flammable and that the oven was made of plywood I kept several fire extinguishers and the hose handy while I heated the pvc.
I raised the "oven" up about 1/2" all the way around so the air would circulate more evenly.



I put a thermometer at the far end and kept the oven at about 280 degrees. It only took about 20 minutes to heat the sheet to where I could flatten it out.
Unfortunately the heater was pointed right at the side of the pvc so it burned the edge a bit. Luckily I only needed about 25" so losing some of the edge was not a show stopper.
Once it was heated enough I put a piece of 3/4" plywood on top of it and rolled the car onto it until it cooled. Instant flat stock!

[gmessler]

Because I was using the wedgewire from the EA sieves I needed to make the Sieve taller (the sieves from EA are narrower and longer.
This also helped because of the depth of my filter pit meant less bricks to raise it to the height I needed.
After I cut the pipe to length I needed to create a level surface.
I used a 2x4 frame and a makeshift router sled to level it.
The pic shows me practicing on the 2nd pipe.
I actually routed both ends.



In order to make sure the pipe to flat stock connection was as close as possible I re-heated the flat stock in the oven.
This time I added a diffuser to keep the heat from burning the edge any further.
Once the flat stock was soft I placed the 24" tube on top of the flat piece so that it molded to the exact shape of the tube.
I then drew lines across the flat stock and up onto the tube so that I could re-align them later.

[aquaholic]

This is a very interesting project. I'm fascinated by your plywood oven as I'd like to bend acrylic sheets and PVC pipe. How high can you heat before the plywood gets too hot? How do you know when the PVC gets soft? How do you circulate heat inside the oven for even heat and how do you stop the heat escaping as your propane gun is exterior?

I'm also very interested in the pressure seive. Why couldn't you raise the walls higher on the open model? You can get wider diameter pipe or an open channel (aquaduct) to supply and drain. Perhaps I don't understand the pressure seive concept correctly.

Looking forward to more of your comments and photos - thank you!!

[gmessler]

Hello aquaholic,

The plywood oven is definitely not a safe idea but on a budget it worked just fine. At one point I was playing with trying to heat different things and had it at about 325 degrees for over 3 hours.
The only issue was when I had the torpedo heater too close to the opening and the edges of the plywood around the opening started to char a bit. I could have probably wrapped the opening with tin foil but It never became an issue.
In order to help keep the heat even inside the oven I raised the entire thing off the floor by about 3/8" with blocks. That allowed the hot air coming in to flow past the part and out the bottom of the sides. There is no bottom on this makeshift oven.

I was very surprised that it only took 20-30 minutes to heat that piece of 3/4" stock to flexible soft. I checked on it periodically to see how soft the part was.

As for the original Sieves, I did extend the side walls by 5" but even lowering the unit 4" (1" safety zone) did not provide the flow I wanted. Another issue I ran into with the EA sieves is that as the screen clogs, the weir just continues to go down. This supplies more and more water which just fills up the area above the screen.
Something else I feel is an issue, but I get why they did it, there's an opening at the top of the screen so that if the screen clogs the water just flows out through that opening direct to the pump. Unfortunately because of the way the sieve is designed the incoming water runs past the screen causing a swirling motion and all that waste that collected on the screen and collection area at the bottom of the screen now goes through that "emergency" exit filling the pump with all that muck.
This became an issue for me because there were several 3-4" fish that had made their way into the sieve. I was busy and decided to come back to clean the screen about 30 min later and the fish were gone. That's when I discovered the opening. Needless to say I had quite the mess with all the ground fish in my pumps and filters.

As for the feed to the sieve. It's a fixed 100mm pipe that goes to a bellows that feeds the weir. There's no way to increase the input size.

[gmessler]

After the heated flat stock with the 24" tube on it cooled I turned the tube over and then placed the flat stock back on the top being careful to align it to the exact location it was marked at.
I drilled three holes through the flat stock into the tube and used drywall screws to temporarily hold what would become the bottom in place.
I used a flush cut bit in my router and followed the contour of the tube. In hindsight I should have used a much smaller bit. I used a 1/2" when a 1/4" would have made it easier and not had so much "sawdust"?

One thing I can say about this project...the amount of pvc sawdust created seems endless.

[gmessler]

The finished piece turned out better than I had planned.
More later on the brown lines on the PVC pipe.

[gmessler]

I next marked the bottom for holes about every 1.5" or so all the way around. I drilled through the flat stock and into the tube with a small bit. Then removed the flat stock and re-drilled those holes larger in it so that the screws wouldn't grab the flat stock but would hold tight in the tube. Knowing that the screw driving into the PVC tube would pull up a little I slightly countersunk the holes in the pipe as well as counter sunk the flat stock.
Next step was to use a coarse sandpaper and remove the charred surface from the outer edges of the inside surface of the flat stock. I did this to help the glue to stick.



Next I coated the first 1" of the inside edge of the flat stock and the mating surface of the pipe with clear primer. Once I felt it was primed enough I coated both surfaces with heavy duty PVC cement.
Working quickly I flipped the flat stock onto the pipe and screwed the two pieces together using stainless steel screws.

[tbullard]

Are you going to glue all of the joints versus plastic welding?

[gmessler]

Hi tbullard,

At first I all different sorts of ideas on attaching not only the bottom but the incoming pipes as well.
Long ago I had purchased a plastic welder but couldn't seem to make it work properly.
Turns out if I had spent some time watching videos on welding plastic and had taken my time I would have learned something.

My thoughts on the bottom were originally just to let the glue / screws hold the bottom in place.
Later on you'll find out how that worked out.

[gmessler]

I moved on from the bottom to the 4" input. I thought I'd give a shot at tapping a hole into the 24" pipe.
I cut slots in a 4" steel pipe and welded a steel bar across the back as a handle.



I practiced on a piece of the cut offs from the 24" pipe.
it worked however it was difficult to get it to start and as a result the hole wasn't straight.
If I were to try this again I'd make the slots a bit bigger because I had to stop about every 1/4 turn to clear the slots.
The idea was to thread it and then glue in a threaded connector in place. I decided to move on to welding instead.

My next attempt at the 4" inlet was to try my hand at welding plastic again.
using the Harbor Freight model 96712 welder.
my first welding attempt was using the Harbor Freight 57731 weld rods. Making sure to use the one that was PVC.
It didn't turn out so well. it was quite burned and didn't look so good. Although later I decided to try to break that partial weld and it took quite the beating before the weld broke.
I turned to youtube and watched many videos and decided to try again but using different weld rods.
The new rods looked like two rods Siamesed together. And they were white so it should look better.
More on the welding situation later.....

[gmessler]

In watching the welding videos one of the things they discussed was scraping off the very outer layer of pvc.
What I discovered with my pipes was that they were very oxidized. Remember the brown lines in the pipe I showed earlier?
That is a result of the oxidization. A bit of scuffing with a sanding disk and I was back in business.
You can see in this pic of my very next weld using the new rods and having the oxidation removed.
You can see that where the old layer wasn't cleaned actually burned.



I only welded around 70% of the way around on the outside.
Then decided to test just how strong the weld was.
It took about 8 to 10 really hard hits with the side of a hammer before it finally broke.
I used the side of the hammer to distribute the blow more evenly so it wouldn't just punch a hole in the side of the 4" pipe with the hammers head.
I was very pleased with the results. the weld itself actually held. It broke the PVC out of the 24" pipe instead of the weld breaking.





Knowing that the finished product would be welded on the outside as well as the inside I was feeling pretty confident that welding would work just fine.

[gmessler]

Here's the inside of the 4" to 24" pipe connection.
I think the weld turned out well. The outside looks pretty much the same with a little more brown on it.

[gmessler]

I purchased a 10" PVC pipe for $100 for a 10' length from Craigslist.
There were several purposes for this. First so that I could create some flat stock.
And to make the water way from the 4" input up to where the weir would be.
I'm sure there's plenty of other ways of doing this.
My thoughts were that if later I decided to add a 2nd feed pipe I could put it anywhere between the existing pipe and the weir.
So far my cost for making two of these filters is $300



The above pic was a section I cut off to make flat stock.
A quick trip to the plywood oven then a little time between the sidewalk and a piece of 3/4" plywood with the car on top made more than enough flat stock for now.

[gmessler]

Next step was to work on the water way that brings the water from the 4" pipe up to the weir.
I put a piece of heavy paper on the end of the 24" pipe and traced it's radius.
I also cut a portion of the 10" pipe that would be the transport.



I cut the 24" radius off the paper then transferred that to the piece of flat stock.
Then fitted it to the 24" pipe to check fit. A couple of trips between the 24" pipe and the belt sander and I had a perfect fit.
Placing the 10" partial pipe on top of the flat stock I marked the Cut line for the flat stock.