UV Impact on Bacteria and Acropora

[Variant]

As of late, I've been reading threads on how bacterial diversity is one of the pillars that defines a mature reef tank. I've also been reading how this in turn is beneficial for sensitive corals like acropora. I think for this reason @Randy Holmes-Farley doses carbon to keep a healthy bacterial presence in his reef.

If all of this is true, would running a UV sterilizer impact one's ability top keep a mature reef and thriving SPS tank? If the bacterial diversity we are concerned about are surface-only and not water borne bacteria, perhaps running a UV isn't that big of a deal. I know commercial fish hatcheries use UV sterilizers for keeping their fish healthy, but when it comes to reefs, should we be sterilizing the bacteria found in our tank water?

Open to hearing people's thoughts on the matter. If you have experience running successful tanks with and/or without UV, even better!

 

[Spare time]

I do not use a UV (nor do I run a protein skimmer) in my tank because I want to have microbial diversity. I have a lot of filter feeders and I dose phyto frequently. I don't want fry the plankton and bacteria that would otherwise be living in my water column.

 

[Epic Aquaculture]

I run UV on all of my systems, and they seem to be doing well...

 

[Charlie’s Frags]

I run UV on my sps systems as well. I also only run my skimmer for 12 hours while the lights are off

 

[Variant]

I've been listening to a lot of reefers on Youtube and they often mention that beneficial bacteria is on the live rock / sand and not waterborne. Is there actual evidence to back this?

 

[Spare time]

I've been listening to a lot of reefers on Youtube and they often mention that beneficial bacteria is on the live rock / sand and not waterborne. Is there actual evidence to back this?

That beneficial bacteria that they refer are the nitrifiyers but that is just one small set of bacteria. Dr. Tim Hovanec talks about this in his macna talk on cycling. Those live on surfaces but a lot of bacteria lives in the water column

 

[Yas]

I don't use a UV sterilizer, but I know there are many UV sterilizer users who keep their tanks in good conditions. There are also many who keep their tank in good conditions without UV.

So both seem to be ok. I guess it is because of the speed of bacterial multiplication. It's said that bacteria can multiply in 10 to 20 minutes, which could result in 8,000 in just four hours. So the speed of multiplication is so high that UV cannot kill them.

I had once become very lazy and my nitrate level hit 25 ppm that time. But because my tank was fully matured (biologically stabilized?), I had no nuisance algae issue at all. So I came to conclude that even with such high nitrate, if the tank is fully matured, you do not have to depend much on mechanical and chemical filtration.

On the other hand, if you use UV, it would probably kill any organic matters including algal spores going through it, which would save you from algae outbreak without much dependent on bacteria. So even if it kills much of bacteria in the water column, your tank should look fine.

So I think either way is fine with or without UV.

As for the power of bacteria, if you compare a matured tank with a new tank, the difference is obvious. Anything in a matured tank is slimy. Rocks, tubes in a sump, return pumps, etc. I think those things in a matured tank are coated with bacteria. It's super tiny, like 1 micron, and you cannot see, but if you touch any object in your tank, you can feel it. Even a strong UV cannot strip out such slimy bacterial film. And, I believe, such tiny bacteria is processing something. I don't know what, but they are doing something.

As far as I know, this tiny single-cell creature is unbelievably powerful. Things some species decompose include oil, hydrogen sulfide, cancerogenic substance, etc. Not those in a tank, I'm talking about bacteria in general. But all tanks use the power of bacteria to some extent. Some are beneficial, some are not, though.

So I guess UV users do not have to worry too much about stripping out bacteria. I don't know how UV affects the population of bacteria in water column, but those on the surface of objects should grow fine at least, I think.