my 250w mh and t5 combo appears to be bleaching most of my corals.

[mos90]

ive had my 125g setup for about 3 months now with 2-250w phoenix 14k's and 8 -39w t5's,9" above the water. i moved my german blue montis, war coral, frogspawn over from my other tank. from the begining i use eggcrates tops to prevent fish from jumping. after i slowly raised the photoperiod for the t5's to 10 hours and the mh's to 6 hours the corals appeared to doing fine, nice pe, good color and even some repair from an earier stn event from my other tank.

i did some par measurements with the eggcrates on and they were rather low. low 100's in the sandbed to 350 at the surface. my german blue was about 1/2 way up recieving about 200par. and war coral was at 100par in the sand.

i felt that these par #'s were a little on the low side so i removed the eggcrates. within 3 days the war coral lost most of its green and the german blue turned light blue and lacked pe.

i deceided to take another par reading with tops off.
sand=250
middle=350-400
top= 450-600

im wondering if that sudden rise in par is the only reason for this. i think it may have been a combination of 2 things.

1) higher par
2) lack of nutrients. 0-no3 .03po4.

maybe the lack of nutrients along with the added par caused this.

maybe it was only the par.

so what i did is lower the lights to 6" and turn off the mh's for the time being.
i have the t5's on only for 11 hours. with the t5's and no eggcrates par #' are similar to when i had the eggcrates on with the mh's at 9"

its onlt been a few days but i have noticed some improvement. i will snap a few picture tonight.

 

[dzhuo]

I think it's possible that the corals are shocked by the extra light. This is a study of a few selected shallow water SPS and their measured photo saturation point in PAR:

Pavona (photo saturation point: 110 PAR):

Porites lutea (photo saturation point: 90 PAR):

Pocillopora meandrina (photo saturation point: 425 PAR):

Undata (photo saturation point: 200 PAR):

Montipora capitata (photo saturation point: 130 PAR):

Most shallow SPS seems to experience photo saturation point easily achieved with most lighting setups we have so it's possible that more light will shock them to a certain degree. More info can be found in these 2 articles:

Feature Article: How Much Light?! Analyses of Selected Shallow Water Invertebrates' Light Requirements
Feature Article: Super Corals - Montipora undata

i deceided to take another par reading with tops off.
sand=250
middle=350-400
top= 450-600

Are you sure these numbers aren't accurate. From the top to bottom (sand), there is only about 200 to 350 difference in PAR? Your lighting set up should be much more powerful than 600.

 

[mos90]

it may be a little higher at the surface, but definately 375ish towards the middle. that is where most of my sps corals are. i have a teal staghorn that is in a slightly shaded area. par for that coral was closer to 200, it did not show any signs of stress.

i can recheck the surface par but the fixtures are now at 6" from 9".

im going to try the t5's for a few weeks see how thing look. if i see full recovery then i know it was light shock. if they need a bit more light i can turn on the mh's for an 30min to 1 hour for a high noon effect.

for some reason i cant view the photos u posted.

 

[mos90]

good reading. it looks like most acro corals will need between 100-250. some may require a bit more.

 

[dzhuo]

Hm. That's strange. I would definitely recheck the PAR. There is no way a couple of 250w 14K phoenix coupled with 8 T5 produce only 600 at the top. That's impossible unless the bulbs are very old or the ballast is mess up. Are you using any reflector? If so, what kind?

(No idea what happen to the pictures. They show up fine for me)

 

[mos90]

the reflectors im using are decent at best with cheap ballasts. par at 1" under the light is over 2000. bulbs only 2 months old.

 

[dzhuo]

Ah. That's makes more sense. 2000 is reasonable for the setup you have. So I guess when you say "top = 450 - 600", you really mean a few inches below water surface?

 

[mos90]

exactly.

 

[mos90]

corals looking better today. some color returning. alk at 9.2. phos .03. adding some carbon to the system yesterday. ill check no3 tonight.

 

[M007]

No doubt there will be a reaction when you boost the par. I might shorten the photo period for a week or two to allow them to catch up.