life expectancy of a 400w radium on a galaxy ballast?

[mos90]

i am running 400w radiums on galaxy switchable ballasts set on standard 400w.

they are 4 months old and have not noticed any change in par or color yet.

ive read that normally 9 months is tops, but was hoping to squeeze a year out of them.

does anyone have experience with these bulbs on galaxy ballasts?

is the color shift noticeable?

[Jeremy B.]

You can squeeze a year out of them, but growth rates will go down (not sure if you'll actually notice it or not, but they will), and coloration could suffer a little bit. The biggest difference you'll notice is how much brighter and more blue the new lamp is when you put it in after this time frame. You're not noticing much color shift, if any, right now because you look at your tank every day.

[mos90]

i will plan on 9 months. i think that might be best. i will stagger replacing the bulbs over three weeks.

now the hard question. how long to run them each day. right now im at 5 hours. and t5s for 8. its not long enough, i dont think. some of my sps on the sand are browning.

[alton]

Switch to 250w, I have gotten over 20 months on one lamp and you cannot tell the old or the new which was which. Less than 10% drop in PAR, I am averaging 16 months because not all lamps last the same. The worse one only lasted 12 months. The fixture that held the 12 month lamp, now contains a lamp that has lasted 16 months and still at about 8% drop.

[mos90]

i tried the 250s. they did not provide enough par. my tank is 26" deep and the light is 10" above the water.