You Learn Something New Every Day - UV Sterilizers and Ich

I've been in this hobby for nearly 30 years and as long as I've known about UV sterilizers I've been under the impression that they will kill ich in its free-swimming state. While I won't say that my impression was wrong (UV will kill almost anything at sufficient exposure) I found out today that the exposure required to kill free swimming ich is far beyond the capability of most standard aquarists and probably not economically practical.

What the...?

Well I saw a table today that showed the dosage required to kill a variety of organisms. The values were in uW-s/cm2 - or - microwatt-seconds per square centimeter - to kill 99.999% of the organisms that pass through it.

A typical 40W UV sterilizer will produce about 15,000 uW-s/cm2 at a flow rate of around 50 gpm. Some will vary up or down based on the housing design. Obviously, to get the most efficiency, you want to turn your tank over as much as possible to get as many of those swimmers to pass through the sterilizer as possible.

Well heck, 50 gpm = 3000 gph, that would turn over even a large tank more than enough.

The problem? That flow rate is, as mentioned, for 15,000 uW-s/cm2. Ich requires 330,000 uW-s/cm2 to kill it. That means that to get a killing dose, a typical 40W UV sterilizer could only be run at about 2.27 gpm or roughly 136 gph. Maybe enough for a nano.

Then add in that the bulbs have to be replaced every 8 months or so at a cost of about $65 per bulb... ouch.

I was looking for something to put on my new 185g and the cost for a viable unit to kill ich would have been well over $1000 and that would have housed six bulbs (average cost per year in bulbs was about $500).

 

Yeah, don't use UV to kill Ich. Use proper QT procedures and keep the water parameters good and feed the fish well (including vitamins and HUFAs).

 

Why not get the 40w sterilizer and hook it to a small independant pump, or run it off a manifold off your main return pump?

~Will.

 

Well recently I bought a Turbo Twist 6X for my 90 gallon tank, and it recommends 110gph to kill off any parasites which I think I can achieve but not sure if it will be effective on a 90 gallon.

So in a month or so, I'll have an experiment with this situation. I've never had ich yet, so it will be difficult to tell if it works or is just a lucky charm. Either way, I'll be making a post eventually on what I find.

 

You'll like it. You'll be able to pop a bubble algae and not worry lots of little bubble's popping up everywhere. If one of your fish or crabs rips up a turf algae that spreads via fragmentation, it's much less likely it'll establish itself elsewhere. If you have a lot of filter feeders that require phyto, you won't have to scrape your glass clean every other day....it will stay clean for a long time.

 

That's what you'd have to do to get the required exposure, but on any decent sized tank running ~100 gph isn't going to cycle enough tank volume through to make much of a difference.

 

Inwall: That's exactly why I was interested in the first place. I was hoping it would reduce any algae build up so I'd have to do minimal scrapping. I've heard mix comments on whether it will work well, so I'm not keeping my hopes up crazy but would be great if it works out. My sailfin blenny is going to have to get use to eating off the rocks and flakes haha.