3 runs then I replace my bulbs.. Around 9 months of use after that they ain't as bright.. U can push out 1 more round but the yield mite suffer & I don't want 2 risk a smaller yield.. After 3 runs u should of saved up a few bucks 2 get another light..

For get the BS of the 1 round switch. That is SO a hydro seller on ya. If I was the place selling you stuff. I tell you to come back in every day to buy something. Or telling you to do mix new cims every day and never reuse old cims. ect....

With core type 12-18mos read in magazines. Digital type 6mos I hear is recommended. I push my digis 3 rounds.

One of my buds wait till his digi uses it for 1 year. Now he wait till it burns out for 1 reason. He said he did a lumen test on his horitlux and lumatek; got his specs. Next day light burns out. He gets a new one. Test again. Same lux what my ears heard?!?!?

Another buddy runs over 20k of lamps. Saw one of his places and things are just moving along till his lights die too...

My thought on lights dieing vs not replacing when recommended. There is a Shield that get block to not let UV come out. Over time it get ware out, and the light is not good for skin/eyes. This is the reason why I will not run my lamps over 1 year.

Safe growing.

I see the problems with these old style lighting is and always will be heat and replacing at lease twice a year. I have found a way of producing and saving money on electric without changing bulbs every six months, not to mention the costs in exhaust fans to buy and run, all costing YOU. I have started using induction lighting, and not all are the same, I found using Inda-Gro Induction lighting has given me the blends of both red and blues needed for the plants. But the real topper is I have a 10 year warranty on both bulbs and drivers!!! An American product made by Americans for Americans. I am able to finish faster due to not changing the light source allows the plants to grow and finish quicker. When you change light sources the plants also have to re-adjust to it prolonging it's natural grow. I have seen an increase in resin production due to the blend of red spectrum as the plant shields itself. tighter buds, and better yields. Did I mention my bill has dropped from 350-375 per month to $169. & change. Yeah I save 2000 a year min. with better results. I too was stuck on "Old School Growing" but have opened my eyes to this old idea revamped to modern success. Live and Learn....You can't grow wrong with Inda-Gro. in my opinion.

Aerojoe found this .pdf about the effects of dimming on HID bulbs, and it will shed some light (sorry) on the discussion of light degradation and effective bulb life.

To summarize, it says that all HID bulbs are affected by light degradation, and that MH is far more susceptible to this effect than HPS. Worse, bulbs' light depreciation- aging- is accelerated by running them on 'dimmed' settings. This aging effect is minor for HPS, but severe for MH, to the point that if you run your MH at 50%, you can expect your effective bulb life to be diminished by as much as 90%!

It does discuss some aspects of how and why HID bulbs degrade, and from a careful reading of this document and others, I say that unless there are some extenuating circumstances- which aside from those mentioned above, I'll address- you should run a 'normal' HPS bulb about a year, or 4500 hours or so at 12/12. For MH, the figure is roughly the same or a bit less, but since many people run their MH bulbs in veg and therefore for longer durations every day, this translates to a shorter lifespan in terms of months of use.

There is a relatively new exception to the above rule; Gavita and Philips have recently come out with a double ended 1000w bulb and ballast system that is demonstrated to retain over 95% of its initial PAR capacity after a full year of use! They recommend that the bulb be replaced in the 2-4 year timeframe, which is a significant step forward. If I find the white paper discussing this bulb again, I will post it here.

Another interesting tech. bulletin I dug up:

EYELU600

And, my current object of luminary lust:

MASTER GreenPower Plus 1000W EL UNP

Runs only on ballast that outputs 400v, PPF maintenance @ 10,000 hours(!); 95%, 10,000 hour life to 10% failure.

Pricey? Sure. A complete kit (Gavita digital ballast, lamp and reflector) runs around $575. You do get what you pay for...

once every 10-15 years :D sorry just like saying it! it's true. only time will tell.