UV dosage for sterilizing protozoa? Trying to calculate appropriate UV Sterilizer size

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Punchanello

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Wow, there is so much conflicting information out there!

I was hoping for some help working this out! After a recent ich outbreak I have had enough. I quarantine and will continue to quarantine but want a fail safe if things go wrong.

My first question is what is the correct UV dosage (µw/cm²) for sterilising cryptocaryon irritans?

I think that from there I would ideally want a UV that could provide that dosage to 3 x the tank volume an hour. Does that sound right?
 
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Just wondering how big is your tank?

http://prolight.info/pdf_specs/Philips_UV_tech_brochure.pdf
Use of ultraviolet (UV) sterilization to kill theronts has been suggested, based on research involving
Ichthyophthirius multifiliis
(freshwater “ich”). The recommended UV dose for Ichthyophthirius theronts is 100,000 μWsec/cm2
(Hoffman 1974). However, UV doses required for Cryptocaryon irritans are anecdotal or extrapolated, and range from 280,000 μWsec/cm2
(industry numbers) to 800,000 μWsec/cm
2
(Colorni and Burgess 1997).

https://www.researchgate.net/public...'white_spot_disease'_in_marine_fish_an_update
upload_2019-1-3_19-57-26.png
 
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My DT set up is approximately 700 litres total water volume.

I saw similar numbers as the ones you have quoted but they are to kill the protozoan. I'm not sure we are aiming to kill them, just render them unable to reproduce and control number. Is that correct?

It would be difficult if not impossible to get death level doses in a home reef tank judging by those numbers.
 
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I would check out the manufacturer ratings for the model UV sterilizer you are looking to purchase. Normally there is a flow chart associated to each model. The flow chart will normally indicate the flow needed for proper UV exposure to kill algae and pathogens along with the recommended max size aquarium. If you can't find a chart on the model you are looking at I would reach out to the manufacturer as a good UV sterilizer should have exposure and tank size ratings available.
 
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Normally there is a flow chart associated to each model. The flow chart will normally indicate the flow needed for proper UV exposure to kill algae and pathogens along with the recommended max size aquarium.

Most have some information but few actually tell you whether the rating relates to killing, controlling or sterilizing algae ich or other. For example, this is what is on the Aqua Ultraviolet chart https://www.aquaultraviolet.com/drupal/sites/default/files/brochures/UV Charts Salt and Fresh Water.pdf -

"Reef Tanks -A UV rated in the 30,000-45,000 columns is ideal for the reef environment .UV’s rated at higher kill rates will destroy the planktonic food supply for the reef. Marine Fish Tanks (No reef or live rock). A UV rated in the 75,000 to 90,000 columns will be the most effective at controlling fish disease. All UV dosages are calculated at end of lamp life (14 months)"

It doesn't tell me what the kill rates are for (algae, bacteria)? I don't know what "controlling disease" means. Sterilization of protozoa?

All of the on line information is missing stuff (for a number of manufacturers. For example, some list the dose for killing protozoa even though I'm pretty sure no hobby grade sterilizer that can fit in a lounge room can claim to do that.
 

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My DT set up is approximately 700 litres total water volume.

I saw similar numbers as the ones you have quoted but they are to kill the protozoan. I'm not sure we are aiming to kill them, just render them unable to reproduce and control number. Is that correct?

It would be difficult if not impossible to get death level doses in a home reef tank judging by those numbers.
Check the specs chart on this link to give some info as they don't ship to aus
https://aquarium.bulkreefsupply.com/search?p=R&srid=S1-2SEAP&lbc=bulkreefsupply&w=Uv&url=https://www.bulkreefsupply.com/emperor-aquatics-smart-uv-40-watt.html&lgsku=204905&rk=2&uid=731765527&sid=1&ts=custom&SLIPid=1546573176049&rsc=3kN5sgIeAv5dOagA&method=and&isort=score&view=grid
 
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Oh for goodness sake, this perpetuated drivel about destroying the planktonic food supply of a reef tank. I have to assume that whomever initially wrote that never has actually kept a tank. Ok, maybe a system that gets continuous natural seawater might have a material planktonic food supply, but otherwise NOT. Benthic copepods or mysids maybe, but water column swimmers that would be affected by the UV? Double NOT. Look up the TMC110 pond sterilizer; there’s a good chart there that lists flow per watt for clarification versus sterilization.
 
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Perfect, that helps a lot.

According to this, for managing protozoa (the manual says altering the DNA and/or sterilizing) it suggests 157 gallons (roughly 600) litres an hour would achieve 180,000 µw/cm² uv dose. That would mean less than 1 x system water volume turnover an hour for me . That's significantly less that the flow rate recommended by AquaUltraviolet who only list a maximum dose of 90,000 µw/cm² and significantly more flow (3660 litres an hour) and don't say whether this would specifically manage protozoa.

Just based on the info the 40 Watt Smart UV gives me a lot more confidence,

Generally speaking does anybody have any views on whether higher flow rate/ lower UV dose is more or less effective than lower flow rate/higher UV dose?

Thanks for all the help so far.
 
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Perfect, that helps a lot.

According to this, for managing protozoa (the manual says altering the DNA and/or sterilizing) it suggests 157 gallons (roughly 600) litres an hour would achieve 180,000 µw/cm² uv dose. That would mean less than 1 x system water volume turnover an hour for me . That's significantly less that the flow rate recommended by AquaUltraviolet who only list a maximum dose of 90,000 µw/cm² and significantly more flow (3660 litres an hour) and don't say whether this would specifically manage protozoa.

Just based on the info the 40 Watt Smart UV gives me a lot more confidence,

Generally speaking does anybody have any views on whether higher flow rate/ lower UV dose is more or less effective than lower flow rate/higher UV dose?

Thanks for all the help so far.

It's all pretty simple across the board, but you have to do some math if you want to know how it will work in your setup...
  • All UV bulbs emit UV radiation (or power/wattage). Most UV bulbs do not use all the "turn on" power and emit it as UV wattage. So you will always have a lower UV wattage emitted from the bulb than the "rated" wattage. For example, a 120watt bulb may only put out 40watts UVC. This is the number you need, the watts of UV spectrum being put out.
  • Second, kill dosages are based on "TIME and radiance" so if you have something putting out 800mW/cm2, it depends on how much TIME that is affecting the area to determine if the target is being killed.
  • 800mW/cm2 isn't a dose of UV, it's just a "power" level. Generally kill doses are rated at "per one second."
  • If you use the calculations, you can determine how much "UV radiance" is hitting the container that your bulb is in at a certain distance (so the distance from the bulb to the wall would be the maximum):
    (Bulb's UV Wattage) divided by [(2pi) times (length of bulb) times (distance between bulb and target)]
  • That will give you a radiance level of your setup,
  • then you can say How much Time do I need the water in the tube to hit my target UV dose?
  • This is a little more complicated, the simple way to do it just estimations, you can say that everything in the tube will at least be hit by the furthest dosage, if the water travels straight and does not spin or change dynamics within the vessel... of course that's not what really happens, water is swishing around and whirling and moving nearer and further away from the bulb the whole way through... so you could do an average distance between the surface of the vessel and the bulb and say "well everything will probably get hit by about that much UV" for example 700mW/cm^2.
  • If you are okay with that estimation, then you can just say, how long do I need those particles to stay in the tube? and you just use volume/speed calculations to see what flow rate you want... if you want to deliver 4000mw/cm^2 for 1 second (as a kill dosage) then you need to divide 4000 by 700 and then get the number of seconds you want the water to stay inside the tube before exiting, giving you the flow rate. So about 6 seconds...
  • ultimately, you want the highest dose that the UV can offer (slowest speed through your vessel) but you are balancing your total tank volume's needs... so you go as slow as possible while still giving a good turnover through the whole tank...
  • Anyway that's what I'd do if I was calculating it again...
 

robert

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I run the Emperor Aquatics HO 120UV on a 400 gal tank - but not for control of ick or velvet.
  • ultimately, you want the highest dose that the UV can offer (slowest speed through your vessel) but you are balancing your total tank volume's needs... so you go as slow as possible while still giving a good turnover through the whole tank...
This is ^^^ correct and in the end is why you really can't control an outbreak of either of these parasites with any practically sized UV - at least I can't. You need a lot of flow to ensure you suck up enough of the parasite to significantly counter the infection rate but at high flow rates the dwell time inside the largest practical UV fixture is insufficient to neutralize enough of the pathogens to significantly change the disease dynamic.

For an in-tank control of outbreak control of ick/velvet mechanical filtration is your best option. I use DE filters for this purpose (>99.99% retention in a single pass) but other forms of mechanical filtration up to 50 microns (with less efficiency) can work as well -
 

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I run the Emperor Aquatics HO 120UV on a 400 gal tank - but not for control of ick or velvet.
  • ultimately, you want the highest dose that the UV can offer (slowest speed through your vessel) but you are balancing your total tank volume's needs... so you go as slow as possible while still giving a good turnover through the whole tank...
This is ^^^ correct and in the end is why you really can't control an outbreak of either of these parasites with any practically sized UV - at least I can't. You need a lot of flow to ensure you suck up enough of the parasite to significantly counter the infection rate but at high flow rates the dwell time inside the largest practical UV fixture is insufficient to neutralize enough of the pathogens to significantly change the disease dynamic.

For an in-tank control of outbreak control of ick/velvet mechanical filtration is your best option. I use DE filters for this purpose (>99.99% retention in a single pass) but other forms of mechanical filtration up to 50 microns (with less efficiency) can work as well -

Which DE filter are you using on a tank that large?
 
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I run it continuously a low speed, I kick it up to high for an couple of hours as needed during or after tank maintenance or when introducing new stock.
If ich or velvet is suspected or present - then I run it on high overnight/low during the day, until the issue resolves - a few days.

The filter itself contains some stainless steel screws - these seem to be of good quality and corrosion isn't an issue. The pressure gauge contains brass and should be discarded - instead watch the flow to determine filter status. Where the pressure gauge would normally be screwed into the body, I instead install a drain valve so I can remove the head for the occasional (every six months or so) grid both cleaning without spilling water.

Installation is the key both for effectiveness as well as servicing. I can flush and recharge in just a few minutes - done right - its actually quite nice and convenient. How often you flush is a function of how much it pulls from the water - With the "bump" feature on that particular model - I flush (between 5 and 10 gallons) and recharge every couple of weeks.

I use straight pool DE powder but the nice thing is that I can also add GAC (BRS rox) and everything works exactly the same with the added benefit of very fast chemical removal.

Apologies to the OP - I don't want to hijack this thread.
 

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I run it continuously a low speed, I kick it up to high for an couple of hours as needed during or after tank maintenance or when introducing new stock.
If ich or velvet is suspected or present - then I run it on high overnight/low during the day, until the issue resolves - a few days.

The filter itself contains some stainless steel screws - these seem to be of good quality and corrosion isn't an issue. The pressure gauge contains brass and should be discarded - instead watch the flow to determine filter status. Where the pressure gauge would normally be screwed into the body, I instead install a drain valve so I can remove the head for the occasional (every six months or so) grid both cleaning without spilling water.

Installation is the key both for effectiveness as well as servicing. I can flush and recharge in just a few minutes - done right - its actually quite nice and convenient. How often you flush is a function of how much it pulls from the water - With the "bump" feature on that particular model - I flush (between 5 and 10 gallons) and recharge every couple of weeks.

I use straight pool DE powder but the nice thing is that I can also add GAC (BRS rox) and everything works exactly the same with the added benefit of very fast chemical removal.

Wow! Sounds like a great idea and I want to do it. You don’t happen to have any pics or videos to help further illustrate do you! Regardless thanks for the info!
 
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