Finally, Cryptocaryon UV dosage data

[Malcontent]

Screenshots because I don't want to deal with removing watermarks.

Values are in the range previously guesstimated.

One interesting tidbit though:

Another important finding was that the theronts exposed to UV doses lower than the minimum lethal dose also lost their ability to infect fish, confirming that UV effectively kills C. irritans theronts.

 

[lapin]

Nice

 

[threebuoys]

Interesting, and seems to be consistent with what we've assumed for the most part.

Page 5, paragraph 2 describes the stumbling block we encounter:

"The application of ozone or UV for parasite control has certain limitations. First, both ozone and UV are ineffective in controlling infection within an individual aquarium because of the adhesive nature of C. irritans tomonts. .......Second, the tomonts are strongly resistant to UV or ozone than theronts, implying that recommended production doses cannot wholly kill tomonts....."

So UV will kill theronts in the water column that passes thru the sterilizer, but will not touch the tomonts. Therefore the tank will likely remain infected.

FWIW, I use the highest wattage sterilizer at top speed. Even if it's not 100%, its better than without, and it kills other pathogens or nasties such as algae or bacteria blooms in the water column.

 

[Roscovitch]

Interesting, and seems to be consistent with what we've assumed for the most part.

Page 5, paragraph 2 describes the stumbling block we encounter:

"The application of ozone or UV for parasite control has certain limitations. First, both ozone and UV are ineffective in controlling infection within an individual aquarium because of the adhesive nature of C. irritans tomonts. .......Second, the tomonts are strongly resistant to UV or ozone than theronts, implying that recommended production doses cannot wholly kill tomonts....."

So UV will kill theronts in the water column that passes thru the sterilizer, but will not touch the tomonts. Therefore the tank will likely remain infected.

FWIW, I use the highest wattage sterilizer at top speed. Even if it's not 100%, its better than without, and it kills other pathogens or nasties such as algae or bacteria blooms in the water column.

“Other pathogens” is a key component very much overlooked. There’s a very large proportion of people in the hobby who automatically assume the three marine diseases most feared at the first sign of flashing (something fish in the wild do all the time). Insightful report and of course relevantly applicable to aquaria.

 

[adittam]

@Jay Hemdal, full text of the study mentioned in the other thread on this topic...

 

[Jay Hemdal]

@Jay Hemdal, full text of the study mentioned in the other thread on this topic...

I got a copy of the paper. One great conclusion is that they were able to determine a kill rate for theronts of 185,000 uw/s/cm2. This has long been open to debate and subject to possible over extrapolation from FW ich data.

They did however, offer this conclusion:

... both ozone and UV are ineffective in controlling infection
within an individual aquarium because of the adhesive nature of
C. irritans tomonts (Ma et al., 2017). Therefore, the focus on UV and
ozone treatment should prevent live theronts flow into aquaculture
ponds....


Jay

 

[forestsofkelp]

I got a copy of the paper. One great conclusion is that they were able to determine a kill rate for theronts of 185,000 uw/s/cm2. This has long been open to debate and subject to possible over extrapolation from FW ich data.

They did however, offer this conclusion:

... both ozone and UV are ineffective in controlling infection
within an individual aquarium because of the adhesive nature of
C. irritans tomonts (Ma et al., 2017). Therefore, the focus on UV and
ozone treatment should prevent live theronts flow into aquaculture
ponds....


Jay

I believe that was the UV dose with ozone. For UV alone it was 269-288,000 uw/s/cm2...bottom of page 3. At 269000 they stop swimming and their membranes ruptured.

 

[Tuna Melt]

Seems like even a mild UV Dose of 69,000 uW/s/cm2 is capable of reducing parasite abundance per fish by 97%. While a dose lower than 269 (but higher than 69) may not kill the theronts, it significantly decreases their ability to infect fish. The question is, does killing them really matter? Won't they just swim around for a few days and then die when they are unable to attach to a fish?"

This suggests that UVs may be more effective than previously thought. I have been researching this topic for a few weeks and the general consensus is that a higher uW/s/cm2 dose is needed for effectiveness (Pentair 280, BRS 180). However, if people knew that they could reduce Ich outbreaks by 97% with a smaller UV unit, perhaps more people would use them and their tanks would be healthier for it. Some people may be able to increase the flow rate of their UVs to catch more theronts without compromising the effectiveness of the dose. FreshbyDesign claims that their Pentair 18W and 25W units are not effective against Ich (as shown in their table below). When I contacted them to ask about this table, they explained that these units cannot be run at a slow enough flow rate to achieve the required dwell time for a 280 dose without overheating. That said I'm sure these units can deliver a dose of 60...

 

[Jay Hemdal]

Seems like even a mild UV Dose of 69,000 uW/s/cm2 is capable of reducing parasite abundance per fish by 97%. While a dose lower than 269 (but higher than 69) may not kill the theronts, it significantly decreases their ability to infect fish. The question is, does killing them really matter? Won't they just swim around for a few days and then die when they are unable to attach to a fish?"

This suggests that UVs may be more effective than previously thought. I have been researching this topic for a few weeks and the general consensus is that a higher uW/s/cm2 dose is needed for effectiveness (Pentair 280, BRS 180). However, if people knew that they could reduce Ich outbreaks by 97% with a smaller UV unit, perhaps more people would use them and their tanks would be healthier for it. Some people may be able to increase the flow rate of their UVs to catch more theronts without compromising the effectiveness of the dose. FreshbyDesign claims that their Pentair 18W and 25W units are not effective against Ich (as shown in their table below). When I contacted them to ask about this table, they explained that these units cannot be run at a slow enough flow rate to achieve the required dwell time for a 280 dose without overheating. That said I'm sure these units can deliver a dose of 60...

Is that from the same paper, or a different one?

One huge issue that people keep missing with UV disinfection as a side stream is dwell time. All of these papers were designed using a flow through model. When UV is applied to aquariums, it is always as a side stream (unless you have it hooked up to disinfect water travelling from one tank to another). There is a unique stage in the life cycle of Cryptocaryon - the tomont stage rests on the tank bottom. When it release theronts, it does so in the early morning. At night, many fish are sleeping in caves or near the tank bottom. They are then infected by theronts because the theronts never got entrained by the UV system before infecting the fish - and the infection can continue.

Jay

 

[Randy Holmes-Farley]

I would just add that any determination of a UV exposure to kill anything will depend on how strongly the water is absorbing that UV before it hits the organism.

I could not find any decent measurements of UV absorbance of reef aquarium water, but I'd note that it might vary a lot.

 

[Tuna Melt]

Is that from the same paper, or a different one?

One huge issue that people keep missing with UV disinfection as a side stream is dwell time. All of these papers were designed using a flow through model. When UV is applied to aquariums, it is always as a side stream (unless you have it hooked up to disinfect water travelling from one tank to another). There is a unique stage in the life cycle of Cryptocaryon - the tomont stage rests on the tank bottom. When it release theronts, it does so in the early morning. At night, many fish are sleeping in caves or near the tank bottom. They are then infected by theronts because the theronts never got entrained by the UV system before infecting the fish - and the infection can continue.

Jay

Yea same paper, its the chart on the top of page 4. I hear you on the side stream piece, the UV only sterilizes what passes through it. I guess the question is how long do theronts take to find a host, if its super quick its unlikely a UV will process many, if its a few hours, and you have decent turnover in your UV (while still maintaining an effective UV dose) that's a different story. I couldn't find much on how long it takes theronts to find a host...

 

[bushdoc]

The conclusion I have drown from this paper is that UV sterilizers used by individual hobby reefers are inefective method of fighting or controlling marine ich albeit Ozone and UV sterilization may be succesfully applied to commercial aquaculture.