Tuesday, 4 September 2012

New Grow Bed - Siphon Strainer

It has been months since my last update. Lots of bad things happened to my system - powdery mildew on okra, potassium deficiency, unexplained guppy deaths, and a dead plecotamus. The pleco was my favourite fish and I still couldn't find a proper place to respectfully bury it so I froze its body in the freezer.

I am now constructing a second grow bed to double the filtration capacity of my current system. In this post, I will roughly show how I designed my siphon strainer. My siphon design is based on Affnan's time tested mini siphon design. I also designed a strainer holder as I do not like the idea of gluing the strainer to the bottom of the grow bed.

I am a perfectionist and I love geometrical symmetry and patterns. To make sure my design is "perfect", I drew guide lines using a mechanical pencil to mark the points where I will be drilling or cutting. I measured them precisely to the limits of my visual acuity. I used various techniques to draw those parallel lines on the pipe. I also figured out a way to obtain the very center of the end cap. There are a total of 4 x 16 holes on my strainer each 10mm in diameter. A chose a triangle design for the strainer holder to minimize obstruction.

To make perfectly aligned holes, I start by drilling 1mm diameter holes precisely on the marks. I then gradually increase their size by using larger and larger drill bits until I reach the desired 10mm diameter size. Drilling the holes using the largest drill bit right away will cause too much slipping as I am using a hand held power drill.

The end cap is cut using a hacksaw with a piece of straight wood used as a guide. The hole in the middle is cut out using a 25mm holesaw.

I removed all access plastic using sandpaper and grind stones. I used an orbital sander to speed up the process. Erased any remaining pencil lines using an eraser. Any stubborn price tag or sticky tape glue can be removed easily using lighter fluid or paint thinner.

I drilled a drip hole on the bulkhead fitting as advised by Affnan. I then removed a piece from the bottom end of the short 20mm pvc pipe so that the drip hole is not blocked by it. I can also close the drip hole simply by rotating the pipe.

Finally, I tested my strainer holder design by assembling all the parts together. The modified end cap is able to hold the strainer securely without obstructing the holes too much. Measuring precisely pays off!

Thanks for reading!

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