View Full Version : when to replace bulbs ?

04/13/2006, 08:16 AM
What is the typical time frame to replace the bulbs. I have 150 watt HQI 's and 96 w PC's. Thanks.

04/13/2006, 08:52 AM
I could be wrong but I believe every 6-8 months on the PCs and just under yearly on the MH bulbs. I'm sure someone else will chime in with more accurate numbers. Are you getting nusiance algae ? That would be a sign, but could also be due to water quality.

04/13/2006, 09:41 AM
Ditto on the PC's, they start to shift and drop in output after about 8 months, but most just go a year with them anyways.


04/13/2006, 09:56 AM
roughly 6 months or so

04/13/2006, 11:17 AM
thanks for the replies. I have 15 k MH in there now but I have some 10 k bulbs. Can I replace the 15's with the 10's. which are better for corals and clams ? thanks

04/13/2006, 11:29 AM
many pc's wont even get past 6 months. whether you want them to or not.

the actinics seem to not last much beyond 6 months, then burn completely out.

i have heard 8 months is when you should swap MH bulbs.

04/13/2006, 02:40 PM
thanks. but what do you all suggest ? 10k or 15 ? I have 15 in now but I have new 10k bulbs. Can I just switch to 10 K's ?

04/13/2006, 05:19 PM
When I have PC 6 to 7 months was the limit. That was only running them 8 hours per day..

I moved to T5 since they are higher output and lower bulb "fee".

04/13/2006, 08:18 PM
The 10k bulbs will do just fine, it's mostly about the way you want your tank to look. 10k's will be more white, and the 15k's will be more blue. The 10k's will make your corals grow faster as well from what I have read. But I would definitely suggest that if you do slap in the 10k's to acclimate your corals to the new light because you will get more PAR out of the 10k bulbs. I just had to move down a coral in my tank tonight that was starting to bleach from too much light. FWIW I'm going from 3-95w PC's to 2 400w 20k MH's so you don't need to be as careful as me I would think. =P

04/13/2006, 08:29 PM

04/17/2006, 07:13 AM
Glad to help !