UV Bulb question

[Snappy]

Just bought a used UV sterilizer that is approximately 3 months old. When inspecting the bulb, it turns on fine. There is a metal coil at each end. Both coils have a small section that glows orange hot. There is a small black spot on the bulb over each hot spot. Are these hot spots normal or are they signs of faulty bulb?

[pdxmonkeyboy]

You are generally ok.  the black spot is from heat. UV units can get VERY hot if there is not water running through them.  So don't have your UV on without water passing through it.  THey last about a year and there is no way to tell if they are still usable.  So the old adage, when in doubt, throw it out applies. 

 

 

[Snappy]

Is it possible to check with a PAR meter to see if its still good or not?

[Blue Z Reef]

You can’t check UV lights with a par meter. I believe more or less if they are turning on, they are working fine. Different types will degrade more or less depending on quality of the bulbs. I’m sure the nicer aquaUV bulbs/units can last a year, but the more basic/cheap models probably will do 9 months or so. 

 

At 3 months old, your bulb has plenty of life left in it. The issues you are seeing could be a defective bulb showing signs of wear earlier than usual. I’d just run it and check it every so often. Also make sure everything is sealed up nice and tight, water intrusion is probably the leading cause of UV sterilizer failure.

[Huntero1975]

also make sure you flow is low enough for the light size and tank size

I run 100gph for my 18 watt uv

If the flow is to high it wont work well.