Does a UV sterilizer interfere with Fluconazole?

danoo · Jul 2, 2019

There doesn't seem to be any specific threads on this topic anywhere and some mixed thoughts I've found within threads. So I'm wondering if somebody with more understanding of how chemicals may or may not degrade under UV light could answer this definitely either way.

GMay · Jul 2, 2019

Looking at the structure I would think that UV would possibly damage the compound and therefore its function.

Brian Treadwell · Jul 2, 2019

I don't know the chemistry part of it , but I have used Fluconazole with my UV running 24/7 it worked as advertised.

Randy Holmes-Farley · Jul 4, 2019

I don’t know if a uv degrades it or not.

KrisReef · Jul 4, 2019

What are you running the UV for? If you don't have an active issue shutting it off for a week probably would not be an issue?
Great question by the way>.

danoo · Jul 4, 2019

I run UV to keep dino populations in check and help prevent them from blooming. And I run a lot of UV, 171 watts on my 350 gallon tank at ~1700 gph. I'm not that concerned about shutting it off temporarily, I'm just trying to figure out if the UV was the reason my first dose of Fluconazole didn't work or if there was some other reason.

I've gone ahead and turned the UV off and re-dosed Fluconazole, so that will give me some practical evidence of whether UV has an effect on the dosage or not. I've had this experience in the past where I dosed Chemi-clean and it didn't work, and then only later did I realize it was because the UV sterilizers degraded the chemical. I dosed it again with the UV off and it worked like a charm.

KrisReef · Jul 4, 2019

Nice.

danoo said:
I run UV to keep dino populations in check and help prevent them from blooming. And I run a lot of UV, 171 watts on my 350 gallon tank at ~1700 gph. I'm not that concerned about shutting it off temporarily, I'm just trying to figure out if the UV was the reason my first dose of Fluconazole didn't work or if there was some other reason.

I've gone ahead and turned the UV off and re-dosed Fluconazole, so that will give me some practical evidence of whether UV has an effect on the dosage or not. I've had this experience in the past where I dosed Chemi-clean and it didn't work, and then only later did I realize it was because the UV sterilizers degraded the chemical. I dosed it again with the UV off and it worked like a charm.

Please report back after the 2nd trial and let us know those results. It could be helpful to know the outcome, I presume you are trying to remove dino's with the Fluconazole?

danoo · Jul 4, 2019

KrisReef said:
Nice.

Please report back after the 2nd trial and let us know those results. It could be helpful to know the outcome, I presume you are trying to remove dino's with the Fluconazole?

No, not dinos. AFAIK Fluconazole doesn't do much to dinos. This treatment is attempting to target Derbesia which has gotten a little out of control.

Steve Fast · Mar 28, 2020

danoo said:
No, not dinos. AFAIK Fluconazole doesn't do much to dinos. This treatment is attempting to target Derbesia which has gotten a little out of control.

how did this turn out?

danoo · Mar 28, 2020

Inconclusive. I did multiple treatments with Fluconazole both with and without the UV sterilizer running and it did not impact the problem, so I have no idea what impact, if any, the UV sterilizer had.

I started using Vibrant and within a couple of months the Derbesia was completely gone.

piranhaman00 · Mar 28, 2020

I kept mine on and the flux still worked fine.

Breadman03 · May 19, 2022

I didn't see an answer, so I went to Google and found a paper. According to an article in The Asian Journal of Medicine, UV does degrade fluconazole. While they weren't studying it in saltwater, it does degrade slightly to significantly under UV exposure per their abstract.

Courtney Aldrich · May 19, 2022

UV efficiently degrades fluconazole as well as most antimicrobial agents used in reef-keeping (see attached paper).

Randy Holmes-Farley · May 20, 2022

Breadman03 said:
I didn't see an answer, so I went to Google and found a paper. According to an article in The Asian Journal of Medicine, UV does degrade fluconazole. While they weren't studying it in saltwater, it does degrade slightly to significantly under UV exposure per their abstract.

The UV used in that paper is a much lower wavelength (210 nm) than used in a UV sterilizer, so I think the answer for reef tank UV exposure is still unknown.

Randy Holmes-Farley · May 20, 2022

Courtney's paper does show degradation at the right wavelength, and that certainly demonstrates it can photodegrade under UV sterilizer light, but I'd again caution at interpretation.

In that study, they use a 10W UV that is continuously exposing the solution to the UV, and it took 2 h at pH 7 to drop the concentration by half.

In a reef tank UV setup, only a tiny fraction of the water volume is exposed at once.

So if it takes 2 h of exposure inside the UV to drop the concentration by half, how long would it take in a reef tank? Might be weeks or months if the volume of exposure inside the UV is only a few mL out of a total tank volume of, say 50-150 gallons.

Courtney Aldrich · May 20, 2022

Randy Holmes-Farley said:
Courtney's paper does show degradation at the right wavelength, and that certainly demonstrates it can photodegrade under UV sterilizer light, but I'd again caution at interpretation.

In that study, they use a 10W UV that is continuously exposing the solution to the UV, and it took 2 h at pH 7 to drop the concentration by half.

In a reef tank UV setup, only a tiny fraction of the water volume is exposed at once.

So if it takes 2 h of exposure inside the UV to drop the concentration by half, how long would it take in a reef tank? Might be weeks or months if the volume of exposure inside the UV is only a few mL out of a total tank volume of, say 50-150 gallons.

I agree. I did some simple calculations and it would take 1-2 months to degrade 50% of fluconazole using a typical UV sterilizer.

aquadise · May 20, 2022

For me it is a No.

I turn on my UV sterilizer (36W) during the treatment (bryopsis and GHA) with Reeflux.
The Fluconazole still work well by eliminating bryopsis and GHA. My tank is 200 liters.

Reason for the UV sterilizer on, because I detect the dino (ostreopsis) come back whenever I try to reduce the nuisance algaes, maybe because of the impact on biodiversity. So I keep my UV on during the time to control the dino, while eliminating the nuisance algaes.

Breadman03 · May 22, 2022

Thank you for the (just a wee bit more educated) advice, @Randy Holmes-Farley.

Jose Mayo · May 8, 2023

Photodegradation of the azole fungicide
fluconazole in aqueous solution under UV-254:
Kinetics, mechanistic investigations and toxicity
evaluation ( https://core.ac.uk/download/pdf/71730415.pdf )

Randy Holmes-Farley · May 8, 2023

Jose Mayo said:
Photodegradation of the azole fungicide
fluconazole in aqueous solution under UV-254:
Kinetics, mechanistic investigations and toxicity
evaluation ( https://core.ac.uk/download/pdf/71730415.pdf )

Thanks. That's the paper Courtney showed in post #13.