I was also looking into probably the same 57watt unit.but again getting conflicting opinions if they are effective or not.
Im nervous to spend $500 on a good unit only to have a crystal clear dino infested tank.
I understand completely. I started battling back in January of 2015 and am just now getting a handle on them. Out of desperation tried just about everything. Dropping the $500 on the UV and having it not work was pretty frustrsting.
I was at the point of doing a full reset and as last resort dropped the money on a larger UV. It worked for me but there are no guarantees.
Some of the mixed results are for various reasons I'm sure. Some that I am aware of are:
Species- UV isn't effective against every species of dinos mostly due to whether they readily enter the water column or not. I found 7 different species of dinos in my tank. The UV only worked on the 3 I mentioned previously. The 2 different species of amphidinium and the 2 species I haven't been able to positively identify were unaffected. I was able to deal with the amphidinium with Dino-X though but Dino-X wasn't effective against those remaining 2 species.
Cysts - some species of dinos, including Ostreopsis form cysts which can later germinate or hatch and cause another outbreak. I found numerous encysted dinos under the scope. When I was treating with Dino-X I had to turn the UV off. After about a week I started to find a few Coolia species again and their population was starting to increase throughout the treatment. I'm sure they came from cysts. Once I completed the Dino-X and turned the UV back on they again disappeared. My opinion when using UV for dinos is to continue to run it for atleast 6 months since cysts can remain viable for long periods of time. For me personally, I will continue to run it for the life of my tank.
From my experience, and from others I have read, size the UV for 2 - 2 1/2 gallons per watt.
Going forward along with the UV I will maintain nutrients at a reasonable level to maintain biodiversity that hopefully out competes any dinos that may get introduced. There is a long thread that discusses this and seems to correlate with what I experienced. My dino outbreaks, first in the 240 then in the 270, occurred when I drove my nutrients too low, either with carbon dosing or gfo or s combination of both.
Sorry for such a long post, just sharing some of what I experienced in hopes it helps in your battle.
