Lighting Part 6 Q&A#2 - Podcast Episode 82

[Rob]

Well, tomorrows the American holiday of Thanksgiving, and sticking with our tradition, i wanted to say thank you to everyone hat has helped support the show and continues to listen and spread the word. Because of the holiday, i am also releasing the show early, this is the show for the week.

In this show Wes is back to help me with Part 2 of the Q&A, in the show we get to fluorescence and Metal Halides, and hopefully wrap up most of peoples lighting questions.




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[Rob]

Reserved for more info

[kalmarrin]

Hi - I tried to find an answer for this before I asked the question, but is there a way to listen to these podcasts without an i-pod or MP3 player? I'm afraid I'm a bit behind the times technologoically.

Thanks,

Pam

[Rob]

no problem, simple click the picture in the main thread, to hear the show.

the best way to get the shows though is by the following.

go to here to download iTunes Apple - iTunes - Download iTunes
once downloaded and installed,
click here:
http://phobos.apple.com/WebObjects/M...st?id=78383725
this will take you to the place to subscribe to the show.

once subscribed, itunes will give you the ability to download any/all past shows, and will automatically download every new show as soon as i release it..

of course itunes isn't the only client out there, but its the most widely used.

[CarmieJo]

Pam,

If you install iTunes on your computer as Rob suggested you will be able to listen to the podcasts right from your computer.

[Astrivian]

Rob, you and wes are so goofy

this series was great man. I learned loads from listening to all these; are you considering a similar series on other difficult topics (maybe sandbeds, substrate, some husbandry and hitchhiker issues...)?

Oh, unrelated to lighting, i would love to see a vidcast on your copepod cultures

okay okay i will leave you alone now. Again, great shows.

[Rob]

yes, there are 2 more series' in the works, expect to hear more in the next couple weeks.

i do plan on a copepod culture video in the future also, just not sure how soon.

[BrianPlankis]

Rob,

Great series on lighting. You addressed a really difficult topic with a great approach Nice to break things up into a long series.

I just thought I would add one (long, but hopefully educational) comment. I have a candycane coral I've had for a while:



It was sitting mid way up my rock and I got it after my old XM 10K bulbs had already been running for several months and before I had my PAR meter. So the bulbs were weakened before the coral went in the tank. It was happy for several months.

Well, every since I put in my new XM bulbs (same brand, same 10K), the coral has slowly declined. Last week I noticed some coral skeleton showing through in a couple of places and the part of the coral angled towards the light was doing noticeably worse than the part angled away. So I immediately moved it down to the sandbed. Within just a few days it has puffed up much more, the tentacles are out more during the day and it just looks a lot healthier.

So I looked over my data from the October issue for that spot:

From MH bulbs:
Old XM bulb reading (average): 122.5 PAR
New XM bulb reading (average): 182 PAR

% Increase: 48.6%

Yes a big increase, but not a particularly large PAR number. So I took my PAR meter out tonight and did a quick reading in the spot where the old readings were taken:

New XM bulb (now 5 months old): 171 PAR

All the data points in my article were taken with a level light sensor. I decided to angle the light sensor at about 30 degrees each direction from level (just like my candy cane) and the numbers were very telling:

Angled towards MH bulb: 240 PAR
Angled away from MH bulb: 98 PAR

Add in the 125-175 PAR from my VHO bulbs and the coral facing the MH bulb was receiving over 400 PAR, while the side facing away was getting less than 200 PAR.

I then took my PAR meter and took a reading just above the coral now on the sandbed:

Angled towards MH bulb: 135 PAR
Angled away from MH bulb: 78 PAR

So a lot less PAR and the coral is much happier. You mentioned in your show that a lot of people are happy with their XM bulbs, but I think the 10K bulbs are just too much par for my 21" deep tank (I can't keep any coral except zoas high up in my tank).

I'm going to have to look at Dr Joshi's tests and talk to other reefers and go to a 12-15K bulb so I can keep corals higher in the tank.

Holey Photoinhibition Batman!

Brian

[Rob]

lol... great info...
here is some other info...
i noticed my candy cane doing the same thing... certain parts were starting to thin out, and the skeleton was visible through the tissue.. but instead of moving it, i started to spot feed it, low and behold, it started to look better and fill out more..

basically the exact same thing as you describes, except instead of moving the coral, i fed it meaty foods more often, and got the same results...

but i think you do bring up good points on coral placement and the idea that there is a such thing as "too much" light

[BrianPlankis]

lol... great info...
here is some other info...
i noticed my candy cane doing the same thing... certain parts were starting to thin out, and the skeleton was visible through the tissue.. but instead of moving it, i started to spot feed it, low and behold, it started to look better and fill out more..

basically the exact same thing as you describes, except instead of moving the coral, i fed it meaty foods more often, and got the same results...

but i think you do bring up good points on coral placement and the idea that there is a such thing as "too much" light

Well, I didn't want to make my post any longer than it was, but since you commented....

Every coral that will take meaty food gets target fed twice a week. So it definitely wasn't a lack of food in this case. Although I did notice the polyps facing the MH light had stopped taking food. I saw feeding tentacles out for the first time in a while from the damaged ones this morning. I'll try to feed it tomorrow morning.

Don't even get me started on too much light

B.

[Rob]

im sorry brian, i didnt mean to to imply your corals were underfed...lol, i know you take care of stuff..

what i really wanted to draw out was that one problem may have multiple solutions, and identifying the correct solution can sometimes be tricky..

[BrianPlankis]

im sorry brian, i didnt mean to to imply your corals were underfed...lol, i know you take care of stuff..

what i really wanted to draw out was that one problem may have multiple solutions, and identifying the correct solution can sometimes be tricky..

Rob, hey no worries, no need for an apology. Yes, there can be multiple sources for the problem. That is the main reason having a reef tank is frustrating at times, difficult to diagnose the problems. You bring up a good point though. Whenever someone has a problem with a coral you can generalize and say there are 5 major things to look at:

1. Flow

2. Water quality in terms of Ca, Alk, NH4, NO2, NO3, P04 and other possible contaminants.

3. PAR reaching the coral and its needs for light

4. Chemical or physical competition from other corals or a predator of some kind

5. Amount of food the coral is getting (either from direct feeding or adsorption of dissolved nutrients).

Whenever one of my corals gets sick I go through this checklist. In the case of this candycane I felt it was highly unlikely that numbers 1,2 and 5 were the culprits. That left 3 and 4 and if it was #4 then the whole coral should have been affected equally or have noticable marks from a predator. Moving the coral has made it look tons better and the only differences between the two spots was lower light and slightly lower flow.

Could there be another reason for its recovery? Of course, but I think in this case that there was enough combined ancedotal evidence and data from the PAR meter to cry photoinhibition. What would be a good followup test would be to allow it to completely recover and then put it back in the high spot and see if it has the same pattern of slow decline only on one side again. But first I'll let it recover.

B.

[Rob]

great info Brian, i knew there was a reason we keep you around..

seriously.. you are right, and thats a good little check list, something good to have.. maybe its time to start better organizing all of this great info our community has come up with.. yeah! another project!!

[Astrivian]

Quick question for this discussion: What is the wattage on your bulbs Brian? Also, what does XM stand for again?

[BrianPlankis]

Quick question for this discussion: What is the wattage on your bulbs Brian? Also, what does XM stand for again?

My bulbs are 175W MH driven by magnetic ballasts.

XM is the manufacturer of the bulb, I don't remember what it stands for

I took a very careful look at the candy cane and the parts that were facing away from the MH bulb still have their green and blue stripe pattern, but the portion that was facing the bulb was bleached out with no stripe pattern visible. It was very subtle, but just POPPED out at me once I recognized it. Yet another clue to photoinhibition.

I fed the tank heavily today and spot fed this coral twice. All but one polyp took food, so things are looking up

Brian

[BrianPlankis]

great info Brian, i knew there was a reason we keep you around..

seriously.. you are right, and thats a good little check list, something good to have.. maybe its time to start better organizing all of this great info our community has come up with.. yeah! another project!!

Good suggestion Rob, have fun doing it!

Seriously, we should talk about this on the phone sometime, hopefully if you mention the words summary artifacts it will trigger my little brain into action.

Brian

[Astrivian]

Rob,
So a lot less PAR and the coral is much happier. You mentioned in your show that a lot of people are happy with their XM bulbs, but I think the 10K bulbs are just too much par for my 21" deep tank (I can't keep any coral except zoas high up in my tank).
Brian

Light is so simple yet so confusing sometimes

Wouldn't the wattage of your bulbs (175) affect par more the temperature? Like if you had 150watts 10K, do you think the results would have been different?

Also, what about screens as a possibility. I believe you mentioned this in your Goni show Rob and Brian, but what if you put a thin screen over the corals that seem to not like the light? Not a lot of screen, just one layer or something. This comes from my thinking with my lighting setup, in the works: if i have too much light, i can always cut it down with a screen or by raising up the hood; if i have too little light, i have to get new bulbs, maybe fixtures, etc., which is more expensive.

seriously.. you are right, and thats a good little check list, something good to have.. maybe its time to start better organizing all of this great info our community has come up with.. yeah! another project!!

Okay rob...now it is time to bring this up I was going to actually suggest this earlier on, some sort of "forum summaries." I was recently trying to convince the IT people (which is you too right rob!) at the community college i work for (Aims) to get us mediaWiki. They kept telling me that we should just use blogs, but using TR and Reefpedia i demonstrated why i liked wiki's better. I told them to do a forum search on wetwebmedia and TR for "Goby" and one on Reefpedia. The wiki found a nice page on the critters, while the forums found many many hits. The question i followed up with was, "Okay, so which would be easier to find the information you want?" Hmm...

Now, having said that, forums are great for ongoing discussions and soliciting information on new topics. And TR is a wonderful source! They can be, however, difficult to keep up with.

Now, i have a suggestion. What if TR teams up with Reefpedia? Perhaps we could formulate, as a group, some summaries of some the threads and post them on Reefpedia as a wiki. You have a relationship of some kind with RP right rob? In a sense, the podcasts are similar to summaries, but i think more appears on the forums than one caster can keep up with

[BrianPlankis]

Light is so simple yet so confusing sometimes

Wouldn't the wattage of your bulbs (175) affect par more the temperature? Like if you had 150watts 10K, do you think the results would have been different?

Also, what about screens as a possibility. I believe you mentioned this in your Goni show Rob and Brian, but what if you put a thin screen over the corals that seem to not like the light? Not a lot of screen, just one layer or something. This comes from my thinking with my lighting setup, in the works: if i have too much light, i can always cut it down with a screen or by raising up the hood; if i have too little light, i have to get new bulbs, maybe fixtures, etc., which is more expensive.

The answer is MAYBE. In theory lower wattage bulbs should yield lower PAR (assuming equal reflectors and distance from the surface). The only difference would be trying bulbs from different manufacturers.

Screens are a definite possibility if you want to go that route. I've tried screens in the past and just did not like the dimmer look, but that is just a personal preference. I think you are right to purchase higher wattage bulbs and use screens to reduce the PAR if necessary.

I'm going to keep my corals lower until the bulbs get older and PAR decreases and then I'll slowly move them up. I'll be going with a lower PAR bulb once these bulbs are due to be replaced.

Brian