Par differential

[tunicata]

Hi Folks,

So, I borrowed a par meter from a friend and am not really sure what to aim for.

Why?

1) I have another friend using a MH fixture and has some of his corals receiving 500-600 par (tested with Apogee Par meter)

2) Another friend with MH 400+ par using MH

3) My corals bleached (not all just 5 of 17 and they are coming back now that I've moved them lower and kept lights max 60%b, 50% w) under 400 par using LEDs with 90 degree optics


So, my question: Is there a par for par equivalency amongst light sources?

If not, how would I know what will bleach my coral and what will not under LED?

If it is the case that LEDs simply do not correspond to any of the existing historic par data for our tanks then how can we go about building new data sets?

I know some people have their corals under 100% blue and white on LED. I am assuming that would give them over 500+ par.
How is that accomplished?

Also, to note, some of the corals I have came from high par MH tanks and maybe a couple came from high par LED tanks but still bleached at 400 LED par.

 

[skene]

Tuni, you do need to keep in mind that the wavelength of light is different from LED/Mh/T5 where an actual glass bulbs will have a varied length going up to its intended spectrum. A 10k mh/t5 bulb does not emit just a 10k spectrum the same way an LED emits 5k spectrum.
Bulbs emit a full spectrum up to its rating. So you get from lets say 1k to 10k vs an on/off 5k from what the LED would be rated. This is why you should be aware of coral placement under an LED vs the latter. Do also keep in mind that LED broadcast light in a very direct manner. Bulbs have a 360* radius which is why reflectors are used as opposed to a lens to help transmit light.
So now that this ends up being clarified, when you take par measurements, did you take it at all different levels, cause if you did then you would notice the sharp drop offs of light as the sensor decends. So that 400 par that you are thinking lets say would be directly under the LED and as you put distance whether horizontally or vertically you will still notice drop off. These are also based on the type of lens that is used on the fixture. The wider the optic the more drop off you will have going vertically, but with less of a drop off if you went horizontally.

Now... there is no par for par equivalent between lighting sources due to variances of wattage/reflectors/lens etc.

How would you know what would bleach and what wouldn't would be based solely on if you rely on strictly photosynthesis vs nutrients for supplemental feedings.

Refer to lighting explanation.

 

[knutez24]

Start at lower pars and a lower % with the leds then increase the leds over time if you think they need more. Easier to give them some extra than to scorch some pieces

 

[vio]

I now , u r in very , serious challenge, to change 17 SPS from T5 to LED is big change, if u ask me before, I will never suggest, u need lots of time to monitor almost every day the corals, set 200-250 PAR first, set just 7 hours the photo. time , increase every week slow (15-20 min. time) reduce the Active Carbon for this period, keep some PO4 from 0.004-0.008, never set 500 PAR the LEDs, do NOT compare to MH or T5 , is totally dif. story. What LEDs light u got any way ?

 

[vio]

I may come over if u want me ? i still have the PAR meter, PM me. I got also IT 20 80 (Custom) Vio.

 

[tunicata]

Hey Vio,
You can come over if you'd like.
I'm free tonight and tomorrow until 5pm.

However, I do have a par meter. Well, I'm borrowing one until next weekend when I have to give it back.

I am going to stick with what it's at right now.

The middle of the tank at the highest point has about 286 to 340. The far sides dip down to 80-100 through the "day".
The front middle with the clam has 200 to 230.

the sand in the middle ish area has 180.

I have the blues go up to 90% for about 2 hrs mid day.
The whites do not go higher than 50% during the same time frame.

I have friends that run them on 100/100.
So, I will slowly slowly ramp. Maybe 5 pts per 2 wks or something.

I'll check later tonight what the par would be if I left the IT2080 at this height but at 100/100.