UV sterlizer yes or no?

[MAXreefer]

I am running a RedSea Max (34 gallons) and have been reading about UV Sterilizers a bit.
I saw there are 2 options: Internal and external.
There are internal ones that look similar to a heater.
My questions?
Are those things really usefull to kill the "bad stuff" ?
Are the external ones better as the internal ones?
Any other advice or suggestions?

thanks for any replies
Michael

 

[sac-bobme]

I use the external ones only, and follow the rate chart they give you, and yes it kills the "bad stuff" very well.