pc lighting and clams

Pyrrhus

Pyrrhus

New member
ive done some research on the amount of lumens that are put out by pc lights vs mh light and the lumens appear to be nearly equal between the two "The 96w Power Compact Flourescents have come onto the market and show a great deal of promise. 96w PC's come in 2 and 4 bulb retro-fit kits. These are rated at 8500 lumens. We took a reading at a depth of 12" of 8000 lumens. This was with one 7100k(actinic) bulb and one 5000k. As you can see this is close to a 175w MH." In D. Knops book he cites the lumens generated by osram ts 250w/d as 19000 lumens wouldnt these produce nearly the same PAR rating? i do know that MH is generated as a point of source and PC is distributed over the whole bulb, regardless of this fact wouldnt the amount of light hitting any one point in the tank be nearly the same? I ask because i just dont see the point of trying to cram MH over my nano which i currently have a Max. and a Derasa in. There seem to be many people in this forum who are so stuck on MH they see PC and say that at any wattage they cant work with clams, i just cant see why not in a 12" deep tank with the light 3" off the water 96w of any light regardless of source seems sufficient to me. I dont see why a 75w MH with supplemental lighting would be better for my clams than the 96w PC.
 
But lumens and PAR aren't necessarily connected. There are incandescent bulb fixtures with just as many lumens as an MH bulb, but they can't sustain corals/clams. PCs just don't have the PAR.

That being said, I still wouldn't put a maxima or crocea under PCs. I've seen WAY too many of them die under PCs, in fact, under a 96 watt powerquad in a 10 gallon show tank at my LFS. Other things in the tank thrive, but clams slowly starve in about 6 months.

Clam dealers will say the same thing....I was just looking at a major clam dealer today and their website says that he onyl reccomends metal halide.

Can clams be kept under PC? Yes, but with the higher light clams they die more than they live. We should have our animals thrive, not just survive :)
 
I have read the same thing from clam dealers and have recently read D. Knop - Giant Clams cover to cover. In all due respect to your LFS I highly doubt that they give the same amount of care to their animals that i do. i dose with DT's 2-3 times a day top off morning and night keep temp rock solid @ 81 degrees check water params twice weekly (8 seperate params) and adjust anything out of the ordinary ASAP. when looking at the scales (growth Rings) of the maxima it would appear that the animal has seen more growth under my previous 51w of PC and NO and my current 96w of PC than even under presumably under the MH or natural sunlight of the dealers, or the MH of the store where he was purchased. I would be extremely interested in seeing a site where the PAR of MH and PC are compared in varying depths of water, if anyone can refer me to one or even do a self analysis using a PAR meter i would be greatly appreciative. im not surprised that incandescent cant support clams regardless of lumens since the color of their radiation is all wrong and not utilized by zooxanthellae. correct me if I am wrong but wouldnt a clam not recieving enough light show a darkening of the mantle due to an increase in the zooxanthellae populatoin to compensate for decreased PAR?
 
I would have suspected that they darken up to, but from all reports I've read they usually just croak.

Congrats on your good luck! I don't think anyone has ever said it can't ever be done....it's just usually not a good idea, one which has resulted in the death of WAY too many clams that wouldhave lived otherwise.
 
A thought....just out of curiosity. How big is your clam? I bet he's totally digging that constant supply of DTs and that's a BIG factor in his growth. Has he "gone fully photo" yet, is is he still small?
 
i do agree that far too many clams have died due to insufficient light, lack of feeding, careless aquarists etc. but the LFS where i buy all of my inverts is run by a well respected marine-biologist who is notorious for not even allowing a damsel to leave his store without a chance to thrive much less a creature as demanding as a clam. btw ive had the maxima for about 2 months now and it has added about a 1/4 inch of new shell.
 
Congratulations on your success so far with clams under PC's. The true test will be if they continue to thrive over a long period of time.

In this hobby there are very few "universal truths". However, when it comes to clams the prevailing opinion of experts is that PC's are not a good light source for clams. Most reefers are not as dedicated as you are to feeding and maintaining water quality. So, while this set-up seems to be working for you, I'd still have a hard time recommending it to others. (This is coming from someone who learned the hard way about trying to keep clams under PC lighting.)
 
guys i really appreciate all the advice given as well as the cautions. I totally understand the hesistance to give anyone the greenlight for keeping clams under PC as that will surely cause the death of many clams, but i think the level of devotion given to the tank also has much to do with its continued ability to thrive for any of the creatures contained within. I deal with aquariums for my livelihood as well as my pleasure and i love a good challenge i spend nearly as much time off the clock with my nano as i do with the 50+ tanks that i care for on the clock and any animal that doesnt continue to thrive can always be put into the MH tank that i have at work.
 
(pyrrhus: Please don't think what I'm about to say is in direct reference to you or anything....I have my fingers crossed that your good husbandry will have your clams thriving...)

I was thinking in another thread and reached this conclusion:

We all know that these creatures usually take 6 months or so to starve....the problem is when they do few people dig up the old threads and say "you were right....I should have listened.....he died a few months later" As a result there are all thse old threads of people "successfully" keeping mandarins in small tanks with feedings and maximas under PCs, etc. It's easy for someone (like a newbie) to see all these old threads and think there's lots of folks being successful, when the true number is very, VERY small.
We should all keep that in mind. There are people having success in those situations, but the number is quite small.
 
please believe that i will be the first to come back with my tail between my legs and admit to having one of my critters die on me, and i always admit it when i give bad information. hell my fire shrimp is starting to attack most of the critters in my tank including my clams. ive noticed a small tear in the exhalant siphon of my derasa and even caught him trying to snag a piece of him. the derasa was purchased last week and was under MH for about a month in my LFS when purchased, so i dont believe it is the shrimp "smelling death on the clam just getting vicious for some reason or another.
 
was doing some research on PAR in the lighting forum and found this bit of info "Here are a few interresting stats I found or calculated:

Use a 250W Iwasaki as a base for comparison:

To equal the PAR, it takes appx:
14 ft of VHO (3.5 4ft lamps)
5 x 55W PC
10 x 4ft NO lamps
19 x 100W incandescent bulbs

All of these figures area assuming the correct magnetic ballast for each lamp.

So, as an overgeneralization comparing PAR:
250 W of MH = 275 W of PC
250 W of MH = 385 W of VHO
250 W of MH = 400 W of NO
250 W of MH = 1900 W of Incandescent

at this link http://www.reefcentral.com/forums/showthread.php?s=&threadid=230985&highlight=PAR+value+comparison

obviously this is second hand info at best, anyone who can shed more light on the subject (no pun) a post would be appreciated.
 
can anyone debunk or verify these figures? if they are correct i dont see how MH is supposed to make that big a difference in a small tank such as mine.
 
I see nothing to make me not believe those figures. The problem is aside from the numbers. (I might wonder about the incandescent...I don't think those can sustain zooxanthalle) First, watts can be VERY deciving since different bulbs produce different amounts of PAR. Different ballasts further change the PAR produced. Have you seen these numbers on 250 watt bulbs....they are VERY illumenating (no pun intended) http://reefcentral.com/forums/showthread.php?s=&threadid=254667
I would suspect thaat similar differences exist between other types of bulbs and ballasts, PC, VHO, etc

Let's make life easier and assume that every bulb and ballast of every type produces the same PAR. A significant problem is found in the physical construction of the bulbs. MH is a point source light and really "punches" the PAR down through the depths of the water. All that PAR is coming right oout of that little one inch inner envelope. With a 6 foot VHO tube or 36 inch PC bulb for example, the PAR is spread out over the entire length of the bulb. A clam placed directly under a MH bulb would recieve darn near all the radiation that bulb has to offer. A clam placed under 250 watts of VHO would recieve a fraction of the light due to it not receiving light from all of the bulbs, and the PAR not penetrating the water as well.

Anyway....lighting will ALWAYS be debated in reefing circles like this. The one thing most of us will probably agree on is that a proper MH setup is the closest thing we have to real sunlight. Does that mean certain clams can not be kept under certain VHO/PC setups...no :)
 
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