MH Bulb Question

cccharliecc · Mar 9, 2011

If your MH bulbs are old, will they cause algae to grow just like old PC and T5 bulbs?

butts182 · Mar 9, 2011

I believe that the can cause algae to grow if they are old enough...it's always a good idea to replace them around 1 yr or so depending on how long of a photoperiod you have...you own it to your tank to keep up with good bulbs!!

fsu1dolfan · Mar 9, 2011

butts182 said:
I believe that the can cause algae to grow if they are old enough...it's always a good idea to replace them around 1 yr or so depending on how long of a photoperiod you have...you own it to your tank to keep up with good bulbs!!

Ditto this...I also believe the PAR values can start to decrease over time as well. Good idea to keep the old ones as a backup though just in case!!

Captain Nemo · Mar 9, 2011

fsu1dolfan said:
Ditto this...I also believe the PAR values can start to decrease over time as well. Good idea to keep the old ones as a backup though just in case!!

+1 to this! I agree with 182 also, we do owe it to our tanks to keep the bulbs changed just like keeping our water quality up to par.

dakotasreef · Mar 9, 2011

As the spectrum shifts in the bulb it can become more conducive to algae growth. Some bulbs can shift colors faster than others also. It also can depend on bulb and ballast combos as to when you should switch bulbs.

I overdrive my 400w radiums and they usually need to be replaced about every 7 months.

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Paul_N · Mar 9, 2011

I am going to play devils advocate here...:xd: I think we change our bulbs out a little too early. I did an experiment before I took my 75gallon down. I ran DE 250w Phoenix 14k bulbs on it. For the first 12 months I ran them 8 hours a day and then switched my light cycle and ran them for 6 hours a day after that. My bulbs were at month 24 when I took the tank down. I knew I was upgrading my MH lighting so I wasn't going to buy new bulbs then. The par was down but as far as coral health, there was no difference as far as growth rate, color or appearance in general. I did not have ANY algae issue either. Dunno, just an observation. I still can't find an article for the life of me but there was mention that the par drop off in MH bulbs was more severe in the first 3 months of the bulbs life. Between months 3 and like 18 I think the drop was minimal. I'm not saying to run bulbs for 2 years but when I see people switching bulbs at 9 months and they don't have a par meter, just makes no sense to me. You cannot tell how much the par has dropped by just looking at your tank. Let the flaming start....:tongue: Let me know if anyone else remembers seeing that study in par drop off. Now there are special circumstances like if you are over driving Radium bulbs and what not.

ksc · Mar 9, 2011

Actually, my 250 Radiums ran @ 320 watts have lost less par than my leds...... I lose about 10% in the first year, but that 10% is lost in the first few months. I have one that's running on a frag tank that is 18 months old.
Light Output of the Phoenix 14,000K DE MH Bulb Over Time by Allen Chantelois - Reefkeeping.com

Paul_N · Mar 9, 2011

ksc said:
Actually, my 250 Radiums ran @ 320 watts have lost less par than my leds...... I lose about 10% in the first year, but that 10% is lost in the first few months. I have one that's running on a frag tank that is 18 months old.
Light Output of the Phoenix 14,000K DE MH Bulb Over Time by Allen Chantelois - Reefkeeping.com

That's the article!

btkrausen · Mar 9, 2011

Great article. I'm running the Phoenix 14ks, and when I changed out bulbs in January, I couldn't notice a single difference, nor did my corals have any ill effects. The bulbs where in there for probably 11 months.