how many days roughly does a hps last on 12/12 or 18/6??

Originally Posted by brewing,up

days, weeks, months, years?

years ... dependent on manufacturer. Phillips make the best bulbs.

venture, are they any good?

i find the cheap grolux bulbs burn out real fast sylvanna grolux worst bulbs ever
the regular spectrum osram and philips bulbs last for years
i am using the philips adjusted spectrum PIA green power bulbs they seem good sofar, not sure they are worth the extra cost over regular sodium's though

if you only have 1 or 2 lights changing the bulbs when they lose 10% of their lumen output is possibly a good idea they should still last several crops before they lose any output at least a year of use on 12/12 .. i have bulbs that are about 4-5 years old working perfectly
if you have more than 1 or 2 lights losing 10% of the lumens would make little difference to the overall output if you have plenty of light on your crop to start with
a light meter would give you all the answers you need, you can rent them from photography stores etc they are quite expensive to buy

peace

3grows and get new bulbs...simple as that....keeping them years.....he he lmfao........... so dam funny

sweet...

Do the math...If a bulb is rated at 10,000 hours, 60 days of 12/12 is 720 hours or 7.2% of the bulb's life. 3 grows and you are at approx 78.4% bulb life, if the numbers were accurate to begin with.
So guys, what is the least % do you want to grow with? I think unlucky is right...after 3 grows I might send the bulb to the veg room or use it as a side light and not a main overhead grow light....IMHO.....or you can just keep using them and be mindful of how well the crops are growing. Good question

Originally Posted by unlucky

3grows and get new bulbs...simple as that....keeping them years.....he he lmfao........... so dam funny

Whats so funny is that you didnt read the OP's question. He asked how long did they last and not how long should you use them. lmfao indeed.

Originally Posted by Brother Numsi

Do the math...If a bulb is rated at 10,000 hours, 60 days of 12/12 is 720 hours or 7.2% of the bulb's life. 3 grows and you are at approx 78.4% bulb life, if the numbers were accurate to begin with.
So guys, what is the least % do you want to grow with? I think unlucky is right...after 3 grows I might send the bulb to the veg room or use it as a side light and not a main overhead grow light....IMHO.....or you can just keep using them and be mindful of how well the crops are growing. Good question

Well done for doing the math but again youre not answering the Op's question. If youre debating how long 'should' they be used for then the only real way to know is with use of a light meter. You can't rely on what a manufacturer states, they typically understate the useful life because they want you to buy more bulbs.

like unlucky said 3 grows then ill change thats all i needed to know, keep your sarky comments to yourself monkey boy