UV-C Pondage

Given the UV steriliser I bought on Facebook Market has been beavering away for over a month now, doing some heavy duty algae killing, I thought I'd check the internals to see whether the quartz tube the UV strip light sits in had become clouded with dead algae.

It's a relatively simple procedure; the water circulates through two chambers shaped like a twin aqualung, each chamber having a quartz tube, which is sealed at the ends with an O ring, inside of which sits the UV light, so it stays nice and dry.

The circuitous route through two chambers means the water is exposed to the UV-C over a length of about 6 feet to maximise the exposure of the algae in the water to the sterilization process.

One simply pulls off the blue, plastic end cap on the UV tube, then unscrew the cap holding the quartz tube in place. Pull out the UV tube, being careful not to touch the glass (hand oils can shorten its lifetime). The quartz tube then slides out, leaving the O ring at the other end in place.

You can just make out the UV tube above.

Below is a view looking down a quartz tube.

It's a relatively simple, but highly effective design.

There was a light misting of dead algae at one end of the quartz tube I extracted, but nothing serious, so I didn't bother dismantling the other chamber. 

I currently have it lying flat on the ground, but when I install the filter in the shed then I'll need to fix it vertically to the wall. To reduce the resistance to the pump I may fix it horizontally near the floor.

The recent hot weather and very sunny conditions have allowed the algae to multiply beyond the capability of the makeshift system I installed, but not by much. A few dull days and it will catch up again.

The box filter I made requires the fine, foam rubber filter to be squeezed out two or three times a day to prevent if clogging, backing up and overflowing. That's not something I'll be wanting to do with the production system, so I'll be dispensing with those and rely solely on bacterial filtration before UV sterilization.