lighting question

[kpiotrowski]

I have a 120g peninsula with 440vho, 2 actinic and 2 white on 13 hours per day. 2x250mh with 6700k Iwaski bulbs that I have been trying to dial in as far as how long to have them come on during the peak of my light cycle. the tank is mosly sps. I was running the MH for 5 hours but started cutting back. I use a 4x54 ho t-5 light when I remove the canopy for maintance and may even use them for several days from time to time. I noticed all my corals really color up after being under only the t-5's, so I started cutting back on the MH. I put some new lps in a month ago and started with MH off, gradually increasing their on time by 30 min every few days and after about 3 weeks I am up to 3 hours. my observation is several corals are bleaching with the MH on for 3 hours, and really color up extremely after a few days of only t-5, they are a cali blue tort, hydnophora triangularis, and monit's. the corals that are NOT as affected are, my lps ( 40+ heads of frogspawn, duncans, elagance coral), green birdnest, scroll corals, pink lemonade acro.

my quetion is...i guess, with running my vho for 13 hours( this I don't want to change), how long should I have the MH on given they are 6700k. it seems a I only need perhaps 2 hours to make everthing happy, but do want to maximize growth at this time too.

TIA!

By kpiotrowski at 2012-03-14

 

[NWDiver]

A couple of questions:
How many total watts of VHO do you have?
The T-5 is a seperate fixture that is not running except when the other lights are off (during maint)?
Why did you choose such a low frequency for the HQI?

-Todd

 

[kpiotrowski]

440w vho. yes t-5 used only when doing maintaince.....and I didn't choose the 6700k, its what the previous owner chose. I got a steel on my tank cuz the previuos owner bought about $6,000 to $7,000 worth of stuff at saltwater city and fought with his condo to let him set it up( which they never did). so 10 years later he put in all on craigslist for $400 and I was the first to reply out of dozens. 10 years old but positively never used. tank wasn't even plumbed and most items still sealed in original packaging. becuase of the many thousand more I have put in to it, I have wanted to at least use the current lighting untill its time for at bulb change.

thanks for your reply! any thoughts?

 

[NWDiver]

Wow! it sounds like you got a killer deal!
Well, if you are running both the vho and the MH during your peak lighting you are dumping a TON of light in the tank, 940w is a lot into a 120 gal.
I'm pretty sure that the 6700k light has great water penetration which is going to put a lot more light at depth. It also grows algea really well, so that might become a bit of an issue for you.
If possible, I would dial back some of the vho lighting while the halides are on, or drop them to 2 hours and run that way for a while. After a few weeks you could try bringing them in adding 15 minutes every week or two.
As to waiting to buy new MH bulbs, your corals are going to freak out when you switch to a higher freq light, so you might want to get that over with now. It will also change how much light for how long, so you will have to go through a bit of this a second time...

-Todd

 

[kpiotrowski]

thanks todd. kinda what I was thinking but wanted confirmation. I currenly only run the mh for 2.5 hours. algea has not been a prob as it seems my 50g fuge eats all nutrients. elos kit says no trace of nitrates and hanna checker says zero phosphates. I'm hoping to replace mh with led and convert the vho to t-5's so yeah, corals are gonna have to deal with it sometime.

thanks agian!

 

[NWDiver]

Sure thing, I was pretty sure you had a handle on it based on how careful you have been

 

[kpiotrowski]

I'm tryin...prob more cautious than most, but still am aware of how little I really know. still curios as to how are my lps ok with my situation and some sps are not as much. lps must come from more shallow water perhaps, where the PUR is more close to my 6700k MH, and sps needings a higher spectrum? if so, and since my tank will be sps focused, I guess a light change is due now right?

anyone want to trade some relativley new iwaski EYE 6700k for some 14 to 18 k's? maybee I'll put them up for trade soon.