How long does it take a UV sterilizer to clear an algae bloom?

[epond83]

Is this a brand new unit? If it's used you might need a new bulb. They put out less and less UV over time and depending on the manufacture they need replaced ever 9-14 months

 

[arkmann]

The bulb is definitely working. The indicator light and the input and output holes of the Via Aqua puts out a green light.

It is a used unit. I think I will try turning the light off for a week while the UV is running and go from there. After that, I might just go ahead and buy a new bulb and if that still doesn't do it after 3 day, I will re-plumb it.