Jebao UV

[Bruce Spiegelman]

Even more so... there are many many many MANY successful reefers that don't use UV at all.

There are many successful reefers that don't use skimmers, water changes, RODI, additives, controllers, or online knowledge bases, but that doesn't mean that we shouldn't strive for best practices, and good animal husbandry. There's a reason that Aqua UV and Pentair supply UV to so many professional aquariums like Steiner and Monterrey -- it works. I had a fairly long discussion with Rich Ross about this and the science is well-know and sound. It's so sound that it's standard treatment for the water we all drink from water treatment plants. It's one thing to argue efficacy of different units, but to dismiss using them is pretty silly.

 

[sfsuphysics]

Not dismissing them nor the science behind how they work, but in the hierarchy of "things you should have a reef tank", I absolutely would not put them into the "must" category at all, and that doesn't mean I'm dismissing what they do at all. Where as something like a skimmer, I would put into that "must" category even though I know it's possible without, it's not something I would recommend someone not do. I mean would it surprise you if I said I run UV? Just because there's something people do doesn't mean that should be the reason for recommending it.

And I'm not quite sure I'd try to emulate what massive aquarium systems are trying to do, sometimes it just doesn't scale correctly, sometimes it's because any problem that arises might be impossible to correct at that scale so having precautions at that level is very prudent. I think the Steinhart runs a fluidized bed filter too, big massive canister of sand, is that something you're looking into? They also have plumbing in the wall so a quick turn allows you to get fresh or saltwater. Is that something you have? Well it is something I do have, and yes it's fantastic! But I wouldn't say others need that level either. I employ tangs as a method of algae control, they are proven, and very effective, I wouldn't say you NEED tangs in a tank though.

 

[JVU]

I don’t agree with you on how this works. I’ll take one apart and see for sure when I get a chance.
There is now way it opaque between the bulb and the water. I think the opaque plastic just directs the water around the bulb (which must have a quartz sleeve around it) but is open on the side facing the bulb. There are definitely older and newer versions so things could have changed over time.
Assuming volume isn’t practical imo since all units will differ there. What it does do is make sure you have an even dwell time for all water that goes through the unit rather than other units that just have an open unobstructed area around the quartz sleeve. In that scenario how do we know if all water stays inthere the same amount of time? Seems like there would be an uneven path of least resistance where most water could move through quickly but some would be lingering longer uncertain areas.
This would also likely be effected by postion of the unit itself (ie horizontal vs. vertical installation) and the orientation of the inlets and outlets.
Some have a single pass with inlet on one side and outlet on the opposite side. Some have I let and outlet on the same end and force water past the bulb one way then back down again to get out.
Certainly not all are created equal.

When I talk about the twist material being opaque being a problem, I’m not saying it blocks all the light. I’m talking about how the light comes off in a sphere from all points throughout the energized gas in the bulb. It doesn’t just go straight out laterally, but in all directions. That’s why you would be able see the whole bulb lit and not just the part perpendicular to the surface of the bulb. So the light rays going nearly straight out perpendicular to the surface of the bulb will have their full effect on that water perpendicular to it, hitting water until they eventually hit the sides of the tube, just like any UV sterilizer.

But the light photons not going out nearly perpendicular (instead going out at every angle), which is most of the light, will have a shortened path before they hit the twist material, not reaching their full effect of hitting as much water as possible before hitting the outer wall. This will waste a significant fraction of the total UV produced by the bulb. Think of it as the twist material partially shading the light that would have otherwise been coming from above and below the level to hit the water at a certain point.

As far as the concern about not all parts of the water getting a consistent flow and dwell time in an open design, that is true. But the tubes are designed so that on average water flowing through it will get the appropriate amount of radiation. Not perfect but a reasonable estimate. A lot better than blocking a lot of the light.

 

[Coral reefer]

When I talk about the twist material being opaque being a problem, I’m not saying it blocks all the light. I’m talking about how the light comes off in a sphere from all points throughout the energized gas in the bulb. It doesn’t just go straight out laterally, but in all directions. That’s why you would be able see the whole bulb lit and not just the part perpendicular to the surface of the bulb. So the light rays going nearly straight out perpendicular to the surface of the bulb will have their full effect on that water perpendicular to it, hitting water until they eventually hit the sides of the tube, just like any UV sterilizer.

But the light photons not going out nearly perpendicular (instead going out at every angle), which is most of the light, will have a shortened path before they hit the twist material, not reaching their full effect of hitting as much water as possible before hitting the outer wall. This will waste a significant fraction of the total UV produced by the bulb. Think of it as the twist material partially shading the light that would have otherwise been coming from above and below the level to hit the water at a certain point.

As far as the concern about not all parts of the water getting a consistent flow and dwell time in an open design, that is true. But the tubes are designed so that on average water flowing through it will get the appropriate amount of radiation. Not perfect but a reasonable estimate. A lot better than blocking a lot of the light.

I understand this point, but again you are making assumptions. How thick is the plastic directing the water? How close does it get to the bulb? Maybe it blocks a lot of light, maybe not. Also, the light traveling further from the bulb becomes exponentially weaker the farther it travels, so the most effective part of the light is the part that is going the shortest distance to hit the water, which is the part going straight out.

 

[svreef]

@thanh510 I came to the same conclusions you did: bad reviews on other products and I didn't find anything to justify Pentair's higher prices. So, I ended up with Aqua UV, which seems solid and has good documentation.

 

[rygh]

I had one of those twist-UV units in my old tank. The twist is cheap plastic.

The fact that they made it black is mixed.
It should have been white to scatter the light back to the water, and not waste photons.
But black is far easier to make UV resistant, since the surface absorbs photons and keeps them from penetrating
and then disintegrating the plastic.
Reflective would be ideal, but hard to do cheaply in contact with water.

 

[rygh]

I like UV for water clarity.
But it is key to replace those bulbs regularly!

 

[Bruce Spiegelman]

@thanh510 I came to the same conclusions you did: bad reviews on other products and I didn't find anything to justify Pentair's higher prices. So, I ended up with Aqua UV, which seems solid and has good documentation.

I've used both kinds and find them equally good. I have bought a few Pentair most recently just because I have found great open box pricing on them, but when I was in the market I would have been happy with either. I aslo like the points and perks I get with BRS.

 

[thanh510]

I've used both kinds and find them equally good. I have bought a few Pentair most recently just because I have found great open box pricing on them, but when I was in the market I would have been happy with either. I aslo like the points and perks I get with BRS.

The price difference between AC and BRS + shipping for points is not worth it. AC got it for $25 cheaper. I am all for supporting LFS.