Clear plastics for DIY UV sterilizer

Reefs and Geeks · Mar 24, 2021

Hello,

I want to build a DIY UV sterilizer, but am having trouble finding acceptable materials to use to transmit the UV through from the bulb to the water. Any recommendations, particularly plastic if it's an option, for clear material that will both transmit UVC and not be degraded by it over time? Is glass the only option?

Also related, I haven't looked as much into it myself yet, so the answer might be out there and relatively easy to find, but what kind of o-ring material should be used with UV light? Are Buna or Viton okay?

A bit of background...

For a long time I had always wanted to try a UV sterilizer, but avoided it due to the cost. I wanted to build one instead, but never got around to it partly due to the cost of a good bulb and ballast. Eventually I got a Jebao and while it seemed to help, I wasn't happy with it. I ended up upgrading to an aqua UV, which I like more, but even with an appropriately sized one, I still wish I had something a bit more powerful, and just can't seem to get the idea of making one myself out of my head. I'm a strong DIY type of person, and would prefer to DIY on most projects, even if it's not a cost savings to do so. I've been wanting to make a UV sterilizer for years now, and don't think I'll be satisfied until I do it. I now have the means to make one (even if it costs as much or maybe even somewhat more than a commercially available one) and really want to do it as a fun project and a bit of a challenge. I'm mainly hung up on the glass tube that's traditionally used for housing the bulb. My design ideas don't necessarily need to be round, so even a flat sheet of material would do fine. I like the idea of plastic for it's workability compared to glass (more DIY!) so would prefer that if possible. If that's not an option, than I'll just make my design work around using glass.

Thanks!

mickeysreef <*))))< · Mar 24, 2021

its not a coincidence that everyone uses glass. maybe time to look into making glass as a diy

threebuoys · Mar 24, 2021

You've probably already thought about this, so apologies if you are already beyond this point in your project.

I believe an advantage of a glass shield to surround the bulb is to provide a means to remove the deposits which will accumulate there from the minerals in the saltwater. Removal of the deposits from plastic without damaging the sleeve to the point the UV rays are degraded would be more difficult. Wish I knew of a better option because this is a project I've often considered.

The O-rings material will be dependent on whether they are directly exposed to the UV or not. The ideas I've had would likely not expose the seals to the UV rays and would only require protection from the contents in the saltwater.

Good luck

taricha · Mar 24, 2021

quartz specifically is necessary to transmit the germicidal wavelength - 254nm to the water around the bulb. Neither normal glass, nor any plastic I'm aware of will be optically clear at 254nm.

example

Randy Holmes-Farley · Mar 24, 2021

I have plastics in the lab that are used in spectrophotometers, but those are very low UV light levels.

IMO, the main problem is going to be degradation of the plastic, not getting one that works initially. Degradation will cause increased absorbance, brittleness, and eventual cracking.

UV Transparency | TOPAS

TOPAS® COC Qualities UV Transparency Ultraviolet light is key to many modern analytical and diagnostic test methods in healthcare, life sciences, and chemistry. But without UV transparent materials, many forms of analysis would be impossible. Fortunately, Polyplastics and TOPAS Advanced Polymers...

topas.com

"Fortunately, Polyplastics and TOPAS Advanced Polymers provide a line of glass-clear, medical grade plastics with high UV transmission so that tests utilizing UVA, UVB, and with the right grade, even UVC down to 220nm can be carried out with confidence. No other plastic material can deliver this level of UV transparency."

"While TOPAS COC is highly transparent to UV, it is not particularly resistant to long term UV exposure, because UV stabilizers reduce ultraviolet transmission. We have optimized our medical polymers for the best available UV transparency by eliminating UV stabilizers, and thus we do not recommend use in repeat sterilization or other long term UV exposure applications."

Reefs and Geeks · Mar 24, 2021

taricha said:
quartz specifically is necessary to transmit the germicidal wavelength - 254nm to the water around the bulb. Neither normal glass, nor any plastic I'm aware of will be optically clear at 254nm.

example

Dang...good info to have through. Reading more into it, I see what you mean on specifically needing quartz glass. I'll have to see what I can find that's available that I could make use of. Thank you!

Randy Holmes-Farley said:
I have plastics in the lab that are used in spectrophotometers, but those are very low UV light levels.

IMO, the main problem is going to be degradation of the plastic, not getting one that works initially. Degradation will cause increased absorbance, brittleness, and eventual cracking.

UV Transparency | TOPAS

TOPAS® COC Qualities UV Transparency Ultraviolet light is key to many modern analytical and diagnostic test methods in healthcare, life sciences, and chemistry. But without UV transparent materials, many forms of analysis would be impossible. Fortunately, Polyplastics and TOPAS Advanced Polymers...

topas.com

"Fortunately, Polyplastics and TOPAS Advanced Polymers provide a line of glass-clear, medical grade plastics with high UV transmission so that tests utilizing UVA, UVB, and with the right grade, even UVC down to 220nm can be carried out with confidence. No other plastic material can deliver this level of UV transparency."

"While TOPAS COC is highly transparent to UV, it is not particularly resistant to long term UV exposure, because UV stabilizers reduce ultraviolet transmission. We have optimized our medical polymers for the best available UV transparency by eliminating UV stabilizers, and thus we do not recommend use in repeat sterilization or other long term UV exposure applications."

Thank you for the info on the degradation. I didn't see that bit when I was searching through the website about the topas coc. It seems clear (pun intended) that I will need to use quartz glass to transmit the large amount of UVC that'll be continuously needed for sterilization. Now I'm on the hunt to see if I can find a supplier, and what options they have to work with

Reefs and Geeks · Mar 26, 2021

I ended up finding a supplier for quartz glass products that had alot of options that could be used. Ordered a few things to try out

I'm reading mixed things on using plastic (PVC) for the sterilizer housing. Reading around, it seems like few plastics are very UV resistant, especially for an application like this. I have seen several times people reference using only furniture grave PVC due to UV stabilizers. Is there even a chance that would work well? I imagine that furniture grade would normally be designed to have outside, so normal outdoor UV exposure. the UVC level in a sterilizer has to be many times stronger than that.

On the other hand, the bigger companies (pentair, aqua uv...etc) use some sort of plastic in their housings and I've not been able to find any complaints about them degrading. I can't say the same about the cheaper jebao ones through, which seem to shed a black substance after being used.

Fun fact in researching components to use...it seems covid has pushed LED manufactures to put extra money into UVC leds and there are a few that have hit the market. Pretty pricy (as expected), but I'm not so sure about how they compare power wise to a traditional bulb. I asked one of the manufactures and they said they weren't sure either, which I found odd. Even at a few hundred bucks for a small strip, it might be fun to try on a build. I doubt we'll see them much in reef tanks for a while until the technology gets cheaper though. Right now it's around $250 for a 14W strip (just the LEDs). I'm sure the price will come down in a few years though.

CarltonCay · Mar 26, 2021

They're $150. How will you build one that works for less, with less headache, and so we don't have you coming back in a few months complaining why your tank is failing?!

This is beyond ridiculous when you are keeping species from the OCEAN in your home.

Randy Holmes-Farley · Mar 26, 2021

Reefs and Geeks said:
I'm reading mixed things on using plastic (PVC) for the sterilizer housing. Reading around, it seems like few plastics are very UV resistant, especially for an application like this. I have seen several times people reference using only furniture grave PVC due to UV stabilizers. Is there even a chance that would work well? I imagine that furniture grade would normally be designed to have outside, so normal outdoor UV exposure. the UVC level in a sterilizer has to be many times stronger than that.

Poor idea, IMO.

The stabilizers used in PVC are often the very ones that leach tin into reef aquaria.

FWIW, some UV sterilizers (e.g., Green Killing Machine) have also been claimed to be the source of antimony in some reef aquaria, and that may be due to excessive use of stabilizers in plastic parts:

The green killing machine

Hey guys I was just wondering if this green killing machine works for saltwater tanks also I ordered it and it should arrive tommorow IVe been watching videos but I haven’t seen anyone using this for saltwater tanks only freshwater please let me know if anyone is running one on their saltwater...

www.reef2reef.com

Reefs and Geeks · Mar 26, 2021

CarltonCay said:
They're $150. How will you build one that works for less, with less headache, and so we don't have you coming back in a few months complaining why your tank is failing?!

This is beyond ridiculous when you are keeping species from the OCEAN in your home.

This isn't at all about saving money. I have an aqua UV 57 watt on my tank right now ($600). This is just a personal project of mine I've always wanted to do, and so I'm going for it. I fully expect it'll cost more than an off the shelf product, and possibly not even work as well? But it's still just something I really want to do. Alot of the DIY projects I've done have been to save money, and I have learned over the years which projects I'd actually save money on, and which ones would end up costing more. This one will be more for sure.

I have been keeping species form the ocean for nearly a decade and have a pretty successful mixed reef with SPS colonies 20' across all grown from frags, so I'd like to think I have some idea of what I'm doing at this point. My tank is by no means failing

Reefs and Geeks · Mar 26, 2021

Randy Holmes-Farley said:
Poor idea, IMO.

The stabilizers used in PVC are often the very ones that leach tin into reef aquaria.

FWIW, some UV sterilizers (e.g., Green Killing Machine) have also been claimed to be the source of antimony in some reef aquaria, and that may be due to excessive use of stabilizers in plastic parts:

The green killing machine

Hey guys I was just wondering if this green killing machine works for saltwater tanks also I ordered it and it should arrive tommorow IVe been watching videos but I haven’t seen anyone using this for saltwater tanks only freshwater please let me know if anyone is running one on their saltwater...

www.reef2reef.com

I didn't think about that, good to know for sure. I wonder what the commercial UV sterilizer companies like pentair use to make their housings from.

If using standard PVC (not furniture grade) do you think there'd be any concerns as far as water chemistry form the UV light? I imagine the surface layer will get brittle over time on the inside, but if the pipe is thick enough, maybe that's not an issue.

Randy Holmes-Farley · Mar 26, 2021

Reefs and Geeks said:
I didn't think about that, good to know for sure. I wonder what the commercial UV sterilizer companies like pentair use to make their housings from.

If using standard PVC (not furniture grade) do you think there'd be any concerns as far as water chemistry form the UV light? I imagine the surface layer will get brittle over time on the inside, but if the pipe is thick enough, maybe that's not an issue.

I'm not sure what they use, or if they have evaluated for release of chemicals from the materials over time, as opposed to simply assessing their stability.