How often should I change bulbs?

[massivecalyx]

I have a 400mh for veg and a 600watt hps for flower

 

[Buddler]

You could buy a light meter to check lumens.Or replace once a yr or so with steady use IMHO .

 

[In~Plain~Site]

I have read that 1 year is the rule of thumb, some cat just did a test with:

1 brand new HPS 600w
vs.
13 mos. old HPS 600w

His results were rather dramatic,see if I can link the thread

Here it is

 

[supermanlives]

every 6 months for me

 

[stonescafe]

every 6 months for me

after every grow for me it gets expensive but worth it for sure

 

[SMOKE-ONE]

After 2 harvest.

 

[spunion]

I've heard you're better off using a cheap brand new $30 bulb instead of reusing a 4 month old $100 bulb.

 

[massivecalyx]

looks like im in the market for some new bulbs then... I usually do all of my ordering from htg. Does anyone have any other recommendations on where to get bulbs online for a good price? Discreet shipping is a must

 

[Cainea]

I'm changing mine whenever my lumen meter tells me about 20% is gone.
That takes about 6-8 months of 12/12.