changing MH bulbs?

[Gazbo]

Well its time or past time to change out my MH bulbs they are about 14 months old. The light is a single unit with 4-96w PC and 3- 250W MH , I am thinking of changing out the outer 2 bulbs first and was wondering what signs to watch out for and should I change the lighting time they are on for about 7 hrs now. The outer bulbs are one the same timer and the middle bulb is on its own timer. I have a mixed tank with sps's close to the surface 4-8" from surface. This is my first time changing mh bulbs and keeping sps coral. I have read where people have burned their corals and so forth. Just want to do this right the first time.

 

[IPisces]

Well, I think the trick to it is to change the MH bulbs closer to every 8-10 months. but since it has been so long, yeah, maybe you should shorten the lighting period and maybe raise the unit up a little higher and then lower it a little over a few weeks to acclimate the coral to the new lights.

 

[kpiotrowski]

all bulbs are not created equal. depending on the photo period some manufactures claim longer usefull life before the spectrum goes caput( usually lower "k" rating, encouraging algae growth). iwasaki and ushio are 2 that I know of that you could get up to 18 months out of. anyhow, I would change them all at once and raise the fixture a foot, lowering it gradually over a few weeks. this keeps the photo period the same for your inhabitants so they don't freak ( including corals) and allows the bulbs thier "burn-in time" while aclimating the corals to the assumed higher par.

if you change only the outer 2 first, then you will still have to acclimate when you change the middle is my thoughts.

 

[Spinner]

I saw a youtube video where the guy has corals growing like mad in a 500 gallon tank using XM MH and he said he hadn't changed bulbs in 18 months? His name is Moser in the large tank builds RC

 

[kpiotrowski]

my biggest concern with running older halides if when they start pumpin out too much UV. I don't have to worry cuz got some LED's figured out for my new build!

 

[Gazbo]

Yeah I was hoping to upgrade to LED but maybe next year. I swapped out all of the bulbs and raised the fixture a foot. So hopefully that works with no effects to the corals.

 

[Spinner]

I have alway's changed mine at one year +- don't believe i will change

 

[mfinn]

I use to change my mh bulbs out once a year.
When I did, I would put eggcrate over the tank and put 3 layers of window screen on the eggcrate to acclimate the corals to the new bulbs.
Every 3 or 4 days I would remove one layer.
Using the window screen material meant not having to mess with the light timers or try and raise and lower the lights. pia imo.