Need help with uv ideas

[duanes]

As others have said.
The problem with using UV to kill ick and other protozoa, is they have motile stages that may (or may not) pass thru the unit long enough to have their organelles scrambled, but also .....have inert stages (on the fish, in the substrate) that will likely not pass thru, so not affected.
Enough detention time to do damage on these complicated, hard cell walled parasites, that flow, must be so slow (much slower than normal filtration rates,) so getting enough of them to pass thru the unit and be eradicated is not assured.

 

[squint]

The low flow rate requirement for UV is one of the greatest myths in the hobby.

 

[twentyleagues]

The low flow rate requirement for UV is one of the greatest myths in the hobby.

Huh? A myth perpetuated by the manufacturer?
So you are saying I have a 9w uv sterilizer and a 1000gph pump I'm good? That combo will kill all the ich and green water in my tank?

 

[squint]

Huh? A myth perpetuated by the manufacturer?
So you are saying I have a 9w uv sterilizer and a 1000gph pump I'm good? That combo will kill all the ich and green water in my tank?

Show me the manufacturer's data and recommendations.

9W and 1000 gph? How big is the tank?

 

[duanes]

Here is a study on the use of UV for Giardia, it is a very similar protozoa to Ick, having a motile stage that would be similar to the target stage for UV in aquaria.
Duration of time and exposure under perfect lab conditions is found in the UV exposure section.
Survival of Giardia lamblia trophozoites after exposure to UV ...https://academic.oup.com › femsle › article

 

[squint]

Here is a study on the use of UV for Giardia, it is a very similar protozoa to Ick, having a motile stage that would be similar to the target stage for UV in aquaria.
Duration of time and exposure under perfect lab conditions is found in the UV exposure section.
Survival of Giardia lamblia trophozoites after exposure to UV ...https://academic.oup.com › femsle › article

At 100 mJ/cm^2 there was no survival or reactivation. The next lowest dosage was 40 mJ/cm^2.

Borrowing numbers from another paper, a 40W bulb at 450 gph yields a dosage of 91,900 µW s/cm^2. If I did all the conversions correctly that's 92 mJ/cm^2.

The chart from UV sterilizer vendor AAP states that "Level 2" sterilization requires 10-12 gph with a 25W sterilizer. The dosage is roughly 25 times higher than the giardia number.

 

[islandguy11]

The low flow rate requirement for UV is one of the greatest myths in the hobby.

I think I have seen you state similar in another thread, and if my memory is correct you also referenced some scientific principle (named after someone starting with an R??) in support of your argument -- I've tried to find that thread since then but can't, if that was indeed you could you please re-post the name of that principle?

Frankly I don't have the knowledge to agree or disagree with your assertion but am keen to learn more about this angle -- and likewise from others who may have similar or different opinions, this is a very interesting and relevant subject.

At 100 mJ/cm^2 there was no survival or reactivation. The next lowest dosage was 40 mJ/cm^2.

Borrowing numbers from another paper, a 40W bulb at 450 gph yields a dosage of 91,900 µW s/cm^2. If I did all the conversions correctly that's 92 mJ/cm^2.

The chart from UV sterilizer vendor AAP states that "Level 2" sterilization requires 10-12 gph with a 25W sterilizer. The dosage is roughly 25 times higher than the giardia number.

Wow, 25 times is no small amount, are AAP's figures really that far off? What about the figures for Level 1, similar? And along the same lines, if their numbers are so out of whack how can average fish keepers determine what are the proper flow rates/wattage/turn over rates we should be shooting for with regards to the 3 levels of sterilization we may be targeting? Any similarly convenient charts you could point us toward or even basic formulas?

 

[squint]

I think I have seen you state similar in another thread, and if my memory is correct you also referenced some scientific principle (named after someone starting with an R??) in support of your argument -- I've tried to find that thread since then but can't, if that was indeed you could you please re-post the name of that principle?

Frankly I don't have the knowledge to agree or disagree with your assertion but am keen to learn more about this angle -- and likewise from others who may have similar or different opinions, this is a very interesting and relevant subject.

Wow, 25 times is no small amount, are AAP's figures really that far off? What about the figures for Level 1, similar? And along the same lines, if their numbers are so out of whack how can average fish keepers determine what are the proper flow rates/wattage/turn over rates we should be shooting for with regards to the 3 levels of sterilization we may be targeting? Any similarly convenient charts you could point us toward or even basic formulas?

There's a whole field of study, photobiology, that's relevant. They have a time-dose (or Bunsen-Roscoe) reciprocity law which states that a dose of light has the same effect whether it's all at once or divided. In real life, some things adhere to it perfectly, not at all, or usually, somewhere in between. Regardless, it means that UV is much more effective than people believe and throws the whole idea that low flow rates are required into the garbage.

There's really only one study on the on use of UV against ich.

This is the setup used, roughly 800 gal:



I couldn't find the specifications for the sterilizer they used online but found several sources for replacement bulbs that were spec'ed at 39-41W.

Flow rate was 450 gph so much higher than recommended by hobbyists or AAP. Low turnover rate (~2X) and a low watts/gallon ratio. I put a 57W on a 125 gal aquarium and 25W on a 75 gal so about 2.2 and 3 w/gal vs 0.5 and 0.1 w/gal.

This setup is basically a worst case scenario for UV yet...



...even a single bulb dramatically lowered mortality.





Now why is it regarded as a fact in the hobby that UV is ineffective?

Why do people simply repeat what they read or hear without question?

It's the illusory truth effect in action.

And why are they wrong so often?

 

[squint]

Dang it, I edited to delete that last duplicate image and it's still appearing.

 

[twentyleagues]

There's a whole field of study, photobiology, that's relevant. They have a time-dose (or Bunsen-Roscoe) reciprocity law which states that a dose of light has the same effect whether it's all at once or divided. In real life, some things adhere to it perfectly, not at all, or usually, somewhere in between. Regardless, it means that UV is much more effective than people believe and throws the whole idea that low flow rates are required into the garbage.

There's really only one study on the on use of UV against ich.

This is the setup used, roughly 800 gal:

View attachment 1401099View attachment 1401100

I couldn't find the specifications for the sterilizer they used online but found several sources for replacement bulbs that were spec'ed at 39-41W.

Flow rate was 450 gph so much higher than recommended by hobbyists or AAP. Low turnover rate (~2X) and a low watts/gallon ratio. I put a 57W on a 125 gal aquarium and 25W on a 75 gal so about 2.2 and 3 w/gal vs 0.5 and 0.1 w/gal.

This setup is basically a worst case scenario for UV yet...

View attachment 1401101

...even a single bulb dramatically lowered mortality.

View attachment 1401103

View attachment 1401104

Now why is it regarded as a fact in the hobby that UV is ineffective?

Why do people simply repeat what they read or hear without question?

It's the illusory truth effect in action.

And why are they wrong so often?

View attachment 1401102

So you are basing your whole anti low flow high intensity campaign on this?
Thr first thing you wrote states pretty much that the reciprocity law is infact just chance and happenstance. That is a theory not a law and it looks to be pretty conclusive it will remain a theory.
And you are also basing it off 1 single test not what manufacturers, hobbiests, water purification techs, have been actually seeing for years. The test leaves out alot of info (maybe I missed it), but how long was this test run, how many tanks were originally infected with the parasite? Its also possible that the filtration system somehow inhibited the parasite from making it to all of the tanks.
Its really hard for me to say OH MY GOD YOU ARE SOOOOO RIGHT! Based off this info.
All I'm saying is qt your livestock so you can treat with meds appropriate to the issue. That way you most likely wont have to worry if a 9w uv sterilizer will kill all the bad stuff you just threw into your 500g tank.