Kessil

Tank Journal - No Tank

Flagg37 said:
Yep, I think it needs a whole redesign. It could be shaped more like a box with the tube
Inside snaking back and forth like in a tankless hot water heater.
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The problem is the light, they typically are going to be linear in nature. Which means throwing that into a tube and letting water flow around it. Now sure there are UV leds on the market that can be used for sterilization but I can't imagine they're very cheap compared to a fluorescent bulb which quite literally is a fluorescent bulb without any phosphor coating on them (why they cost so much I'll never know).
 
sfsuphysics said:
The problem is the light, they typically are going to be linear in nature. Which means throwing that into a tube and letting water flow around it. Now sure there are UV leds on the market that can be used for sterilization but I can't imagine they're very cheap compared to a fluorescent bulb which quite literally is a fluorescent bulb without any phosphor coating on them (why they cost so much I'll never know).
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I think it could work efficiently with the LED. Since the tube snakes back and forth it would require fewer LEDs than if it was simply linear since they would pass by the same LED multiple times.
 
While I can see benefits to a rectangular setup with LEDs I'm not sure how snaking back and forth helps. As you gain length (time) you decrease cross section area and therefore flow speed increases proportionally and you end up with the same contact time per flow rate, but with smaller passages that drive higher frictional losses in the line. A line source on the axis of a tube is pretty efficient as far as avoiding self-shading goes. There's a reason spiral CFLs aren't used on places that don't meet their particular space constraints.

It would be interesting if you could do a shell with two different concentric passages. One close to the UV and one farther away. The section at the higher intensity for parasites, and the section at lower intensity to have higher throughput for algae reduction. Of course the surface fouling on the inside would inhibit this, so I'm not sure how well it would work in practice.
 
Flagg37 said:
They should just make a submersible UV light that has its own internal dc pump to adjust its flow. Then you could just throw it in the sump and plug it in.
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They do! I bought one about a week ago to treat a green water situation in a 100g garage tank. The water was clear after maybe 3-4 days so the smaller model would probably have worked on a longer timescale. I’m not planning to leave it in so it’s nice to have a drop-in form factor.

https://www.petco.com/shop/en/petco...IFNGlog4jDIQGlbg8seXIX5-_s-MUWJkaAiomEALw_wcB
 
Is there any sort of calculator to help size a UV unit? Is it just a matter of watts per gallon/hr through it? Or is there watts per gallon of tank.
 
sfsuphysics said:
Is there any sort of calculator to help size a UV unit? Is it just a matter of watts per gallon/hr through it? Or is there watts per gallon of tank.
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The uniot needs to be sized correctly as well so that it turns over the water in the tank often enough. BRS and others list that info.
 
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