What's Your Lowest Successful PAR Level?

[Dana Riddle]

Given the generic term of sps, but referring to those, how can we tell which species require more light having the clade A? Is it solely trial and error?

See here for details on zoox and some of their lighting requirements: http://www.advancedaquarist.com/2011/4/aafeature

 

[Mattrg02]

How about taking a frag that's coming from "high" PAR and putting it in much lower PAR? Let's say a particular coral can do just fine at 150PAR but has been acclimated to 450PAR before being fragged and put into a new tank running 150PAR?

I have a starburst montipora that either lightens up or bleaches and pulls pack its polyps anytime it wonders (its a frag on an epoxy "mount") into any region running over 100PAR (estimated, not measured) in my tank.

In contrast, I have a WWC Costells Banana acro frag that's at the top of my tank (probably in the 300PAR range) and has browned out.

-Matt

 

[DMan]

I think this is the first thread I've seen asking about min light levels as opposed to max. Dana has been saying it for a while now. But its nice to see the community coming around.

 

[Bruce Burnett]

Wish I owned a par meter. Guess I will save up for one. It has always been more of just something to do as I always worked in another completely different field working 50+ hours a week. Used to use MH and actinics back in the late 80s up until 2007. Out of hobby until 2014 and went with Orphek led lights and I get great growth but I think they may be turned up to high for best color.

 

[mcarroll]

Do you think I'm safe in assuming I could use a lux to PAR conversion factor of 50 or 60 to arrive at PAR values of about 170-200? Good info - thanks!

That's about what I eastimate!

Question....Is a LUX meter the same as a PAR meter..?

It is the same in some important respects....primarily that it can give rational, repeatable light readings. The human eyeball is fairly terrible at this.

As noted, they're different from PAR meters too. Lux meters are designed to "see" what the human eyeball sees: red + green + a small amount of blue. PAR meters are designed to "see" the range of 400nm-700nm "evenly". In practice, it's more or less evenly. Unless you spend top dollar, you're on the less evenly side.

This PAR value is likely on the ragged edge of enough photosynthesis to meet the oxygen demand of the coral and symbiont - the compensation point.

Around 1000-5000 lux are the numbers I've seen for compensation points...even going back to some docs back in the 1930's when they were actually using lux meters. That's about 20-100 PAR (/50). Maybe as low as 14-70 PAR (/70) depending on the conversion you favor, or the light you're using!

How about taking a frag that's coming from "high" PAR and putting it in much lower PAR?

Big lighting changes up or down can be lethal. Frags seem to be a lot more adaptable than colonies, but I can't say I understand why....and I can't tell you the difference between a frag and a colony either.

Wish I owned a par meter. Guess I will save up for one.

Do save up for one. But in the mean time use a lux meter (Beginner’s Lux) – $12, delivered. With pricing being as low as they are, it doesn't make sense to go without a light meter or a microscope in this hobby IMO. (Selecting a microscope)

 

[Dana Riddle]

How about taking a frag that's coming from "high" PAR and putting it in much lower PAR? Let's say a particular coral can do just fine at 150PAR but has been acclimated to 450PAR before being fragged and put into a new tank running 150PAR?

I have a starburst montipora that either lightens up or bleaches and pulls pack its polyps anytime it wonders (its a frag on an epoxy "mount") into any region running over 100PAR (estimated, not measured) in my tank.

In contrast, I have a WWC Costells Banana acro frag that's at the top of my tank (probably in the 300PAR range) and has browned out.

-Matt

I had to Google the popular names of the corals in order to get a better idea of what we're discussing... makes me recall Veron's amusement at some of the coral names he saw at one of the MACNAs. In any case, and this is a seat of the pants answer, I think going from high light to low light would not be all that stressful if the zooxanthellae possess the ability to adapt to lower light to begin with. I have some chlorophyll content data from experiments conducted just before I left Hawaii. In a Porites species, the chlorophyll content was adjusted *daily* in response to changes in light intensity. This flies in the face of the hobby tradition of a 2 to 4 week adaptation period. Don't know if this applies to other species. I need to publish this data before I lose it.

 

[Grey Guy]

Just watched a video from MACNA where a scientist proves that Porites (SPS) grow fastest at about 100 PAR. Blew my mind.

 

[jda]

...probably the guy in the post above you.

BTW - Porties used to grow in my fuge under 60 and 75w incandescent screw-in light bulbs. It did quite well, actually. They are not all that demanding of a coral.

 

[Flippers4pups]

Just watched a video from MACNA where a scientist proves that Porites (SPS) grow fastest at about 100 PAR. Blew my mind.

Yep, that's Dana Riddle that did that study and he's talking on here right now. If you have any questions about the study or anything else related to this thread, ask away, he'll answer it for you!

 

[Scott.h]

Wasn't it more around 200 par though?

 

[mcarroll]

This flies in the face of the hobby tradition of a 2 to 4 week adaptation period. Don't know if this applies to other species. I need to publish this data before I lose it.

I read about experiments that were done in the wild where corals were moved to lower and highter light levels and they had problems (including mortality) both ways. Not sure if I have the article any more.....and unfortunately I don't remember it being specific about what light levels were actually in question or how much control was applied to other factors like available nutrients and flow.

I've also read other accounts like yours where the corals are making continuous adjustments...which does seems to correspond with most folks tank experiences when decreasing light levels.

Hard to say what the difference is (or differences) but it seems like more often than not our tanks ought to have higher levels of dissolved nutrients....and this is known to provide protective effects under light stress....especially available P. Just one guess and one possibility though.

(Gonna have to see if that article is in the collection...)

 

[jda]

I see where you are coming from now. I am doing a similar experiment. I have two frags under a single ATI Blue Plus T5 on AquaMedic that are slowly dying. The bottom one is an unrecognizable Pearlberry and the one on top is a green/pink/white microlaudus encrusted nub similar to most Shortcakes. Both are now different colors of brown - red-brown and green-brown. After about two months, each are dying around the bases and from the tips. This tank is on the same system as my other acropora which are thriving. PAR from a Apogee 510 bounces between 48 and 53 and the bulb is directly above the frags.

Edit - amazingly, the coralline is growing quite nicely under this single bulb. Little dots pop up every week or ten days after I scrape them.

These are all but dead now. I had written the names on the plugs - pearlberry on the bottom and SSC on the top - confirmed. For the first two months, they did OK, started to go downhill for the next six weeks and then died pretty quickly afterward.

That 50ish PAR was directly off of the Apogee 510 - no idea if I need to gross-up that number by 1.32. In any case, this was not enough light. The corals in the same system under my MH have all grown significantly and I have had to dial my CaRx up twice since then.

 

[Dana Riddle]

I read about experiments that were done in the wild where corals were moved to lower and highter light levels and they had problems (including mortality) both ways. Not sure if I have the article any more.....and unfortunately I don't remember it being specific about what light levels were actually in question or how much control was applied to other factors like available nutrients and flow.

I've also read other accounts like yours where the corals are making continuous adjustments...which does seems to correspond with most folks tank experiences when decreasing light levels.

Hard to say what the difference is (or differences) but it seems like more often than not our tanks ought to have higher levels of dissolved nutrients....and this is known to provide protective effects under light stress....especially available P. Just one guess and one possibility though.

(Gonna have to see if that article is in the collection...)

That might be the LaJeunesse article where Pocilloporas were moved to different depths? These showed a poor ability to adapt to low light.

 

[Dennis Cartier]

I have been (inadvertently) testing this in my frag tank. The tank is 16" deep and I have a mixture of SPS and LPS in the tank. Over the past few months any SPS frags that I place in the tank were browning out and dieing. I had to scale my 2 part back to almost nothing as a result. The tank (48x24x16) is lit by a single AP700. Stupid me kept thinking the problem was too high of nutrients. Then I noticed that a whole strip 6" from the glass of Chalices and some Plating SPS were not only surviving, but thriving, most doubling in size. I was puzzled why those corals were doing well, and most others were struggling. Then one sunny day I was home in late afternoon and noticed that the sun would come in through the basement window and strike the front glass and about 6" of the floor of the tank for about 45 minutes. Then the light bulb in my head went off. It was not nutrients that was the issue, it was light.

I had been running may AP700 at 30% as I noticed that my LPS seem to react badly if I went over that. I decided to see just how much light my AP700 was putting out, so I ordered an Apogee MQ-510 meter. When I measured the light levels in my tank, I was stunned to see that the highest par level was 150 par, and that was on a large rock in the centre of the tank with a small colony on it, about 4" below the surface of the water. Most other points along the bottom of the tank were, 60 par all the way down to 25 par. I also measured along the front of the tank when the sun was at the right angle to see what the par level was that the corals were being given each day. I measured 450 to 600 par in the sunlight strip.

To help give me a good baseline of light, I added 2 x 54W T5 bulbs to the tank (along with the AP700). I used coral+ bulbs in the T5s, and the response from the frags was shockingly quick. Everything started to turn around, even the LPS looked better. Now I am getting 250 par on the rock that previously had 150. I have not adjusted the level of the AP700 yet, but I have modified the spectrum to be a lot more white than I was running, trying to match the colour to the coral+ spectrum (by eye). Before, all the frags were so brown that they would only show colour under the bluest of blue light. Now with the much more white coral+ bulbs, they are starting to show their colours without the blue light.

I still have not figured out why some frags were reacting badly to higher power levels of the AP700, but for now I have the coral+ bulbs running for 1.5 hours each day and plan to slowly increase the duration (of the t5's) and see about getting the AP700 levels set properly.

Dennis

 

[BoomCorals]

I have an ap700 over a 48x24x10 frag tank. I run it at 100% and keep sps in it. Works great so far.

 

[Dennis Cartier]

I have an ap700 over a 48x24x10 frag tank. I run it at 100% and keep sps in it. Works great so far.

If you don't mind me asking, what colour setting on the AP700 have you found to be good?

Dennis

 

[BoomCorals]

If you don't mind me asking, what colour setting on the AP700 have you found to be good?

Dennis

It's not the most blue one but the 3rd from the most blue. It's the one that looks kinda purple.

 

[Dennis Cartier]

I have an ap700 over a 48x24x10 frag tank. I run it at 100% and keep sps in it. Works great so far.

Since I have ruled out salinity, temperature, parameters and flow, and your running higher intensity in a shallower tank, I concluded that there must be something I missed. On a hunch I pulled out my TLF veggie clip, replaced it with a new one and pulled the back off the old one. The neo magnet on the old clip had minor corrosion on the surface. Time for some Cuprisorb. Sigh. Guess I better check any other magnets on frag racks, etc.

Sorry for the OT post, but just wanted to follow up for users who might run across a similar situation.

Dennis

 

[mcarroll]

I still have not figured out why some frags were reacting badly to higher power levels of the AP700, but for now I have the coral+ bulbs running for 1.5 hours each day and plan to slowly increase the duration (of the t5's) and see about getting the AP700 levels set properly.

If this was prior to you getting a light meter you may simply have made the changes to large and/or too quickly. In an otherwise healthy, stable system, to be safe I would not increase PAR by more than 30 or 40 per month.

2¢

 

[Dennis Cartier]

If this was prior to you getting a light meter you may simply have made the changes to large and/or too quickly. In an otherwise healthy, stable system, to be safe I would not increase PAR by more than 30 or 40 per month.

That was my concern with the addition of the T5's as well. No way to dim them really, and they are using the same mount as the AP700, so varying the height is out as well. What I chose to do was to limit the duration that they are on and only increase by 1/2 hour every few weeks. Thanks Matt.

Dennis