Wondering about clams and Kelvin values...

[Wardog]

Hello! I'm new to this forum and relatively new to reef keeping... My husband and I have had saltwater tanks (dead coral and fish) since 1990 or so. Converted our 65 gallon tank to fish and live rock last year, bought new lights, switched to live sand, and have been adding live corals since August 2000. We have had a great time with Soft and LPS corals, and are now getting into SPS and clams —Â*which leads me to my problem...

We purchased a 2.5" purple Maxima about four months ago. It has attached itself to a rock about 8" from the surface. This clam has never fully opened up. It opens, but never fully extends it's mantle. It doesn't seem to be "gaping" and definitely reacts when the fish swim over it. It is not in a direct current, and there is no sign of snails or bullying by the fish. It seems to be holding it's own — just doesn't compare to the photos I have seen on this forum. We figured maybe it was just a "bad" clam...

Last Saturday, we bought a 4" purple Crocea. This one was fully open in the store, mantle nicely extended. Looked great Sunday, but by Monday was starting to look like the Maxima. Same for today. I did notice, however, that the mantle seemed to be out more this morning when the Metal Halide was off. When I went to check on it at lunch (Metal Halide on), it was barely open. She (Clarice) is located about halfway up and seems to have attached herself to a rock.

The water quality seems to be in the ranges I have read about (all of the corals look great...) Here are the test results from yesterday:
Phosphates: 0.3
Nitrates: 0
pH: 8.1
Ammonia: 0
Nitrites: 0
Alkalinity: 5.6 dKH (adding C-Balance to get this up)
Calcium: 450
80°
1.023-1.024

I have been searching for answers all morning and am starting to wonder about the light. Found a cool site — On The Half Shell, By Daniel Knop. In his article, "Tridacna crocea — Pearls of the Reef," he says the following:
"Because this clam receives the full spectral composition of the sunlight in nature, I prefer metal halide lamps with Kelvin (K) values between 5000 and 6000. Lamps with higher K values (10,000 to 20,000) that produce more blue spectrum mimic the natural illumination on the reef to a greater depth (e.g., 10 or 15 meters [30 to 50 feet]). This may be ideal for coral species naturally found in this habitat under these light conditions, but it is not sufficient to provide the clams with everything they need."

Our setup consists of the following:
4 – Icecap 660 VHO / 380 watts / 2 Actinic, 2 AquaSun (since 2/00)
1 – 250w IceCap Metal Halide / 12,000K Sunburst (since 11/00)

Could this be the problem? Is anyone else using the 12,000K Sunburst?

Any comments and suggestions will be greatly appreciated! We really want Clarice to make it!

[herefishiefishie]

I would definitely say that 12000K lights would not deliver enough usable PAR ("light intensity," for lack of a better phrase), although I'm not sure this would caause the clam to open up less than usual. Your light setup seems to be very heavily blue. IMO, a change to a lower K rating for the MH bulb would be advisable. Whether this will help, I do not know for sure, but I would guess it would.

There's enough wattage over your tank; perhaps the clams were kept under less intense light at the LFS and need to be acclimated more slowly to the light level in your tank (by placing them on the bottom of the tank and raising them a few inches every few days or so). I don't think that this would apply to the maxima after four months; but it could apply to the crocea.

Your pH seems a bit low (8.1 vs. 8.2-8.4) and your SG is a little less than I would like (1.025-1.026, the level of NSW), but these are minor points. I don't think these would affect your clams in this way.

I assume you have eliminated other factors, such as predators, harrassing fish, and such).

Perhaps someone else can add more.

[CleveYank]

Yes, maybe a gradual light adjustement is in order here till they are ready for the higher power lights in your tank.

However, all of that aside, (if alot of blue the clams should adjust to this and I would not change the bulbs)

But I have noticed that a mild or gentle current make my clams open up the best.

I also turn the clam so that the opening mouth or intake that it is naturally pumping water through so that the intake is facing into this mild or gentle slightly alternating current.

If your clam is in dead calm they don't seem to be as happy...well that has been my experience.

Oh yeah...If you had say 20k bulbs and VHO blues then yes I might say that the bulbs are the problem.

But anything in the 10 to 14K's should not cause a problem and I have seen more pro to their use in the issue of clams.

[CleveYank]

oh yeah

I have 2 10k MH's and two RO blue atinics on the tank at the moment and my two clams are jammin...I even have lots of growth and they are right smack under the blubs...one is 6 inches and the other is 3 to 4 inches from the surface of the water.

My 5 colored crocea is my favorite. Blue/Green/tiny brownish spots / with a gold highlights around the center/ and a indigo highlight around the edge. It has grown 1 inch since I have had it.

Sorry I Don't have any pics, but when I have the money and time they will be posted.

[BurnNSpy]

I recommend fixing the alkalinity problem fast and c-balance will not do it, it is good in the long term but not ad a fast fix.

Add Sea Chem reef builder or baking soda(1tsp each 20gal of tank water. This will add alk fast.

I think that is your problem, alkalinity is underated alot.

BurnNSpy

[MiNdErAsR]

Two things stand out in my mind. First, your phosphate level (0.3 mg/L?) is extremely high. Recommended levels are less than 0.04 mg/L. Perhaps a series of moderate sized water changes, in conjunction with the use of a phosphate sponge would help here.

Secondly, (as you noted) your alkalinity level (5.6° dKH) is well below natural seawater levels. I would suggest bringing this up to 8-10° dKH and even as high as 12° dKH.

These may or may not be the cause(s) of your problems, but should be addressed anyway. Perhaps when it is time to replace your halides, you might consider Iwasaki 6500k bulbs? You have more than enough actinic lighting to supplement these bulbs, and (again) may help with your problem.

HTH

[john f]

"I would definitely say that 12000K lights would not deliver enough usable PAR "

Please try and be a little more carefull.
I have had zero problems with clams under 12000k lights.
Mant reefers have kept maxima and squamosa under 20000k lights as well, and these are considered "low PAR" halides.


John

[herefishiefishie]

Perhaps you should be careful as well. You make the mistake of thinking that if it works occasionally, then it must work generally. Wrong. There are so many factors involved that one cannot really say that because it works once that it is a generally advisable practice.

A couple of contradictory anecdotal cases of clams thriving (so you say) under 12000+K lights is not enough to change my stance, and certainly proves nothing. I think I'll stick with Knop, who agrees that 12000+K lights are not optimally suited for clams.

It's very tiring to try to discuss what's optimal, or advised, when people keep trying to change the subject to what's possible.

So, I reiterate, you should be careful. We're talking about what's advisabe, not what's possible.

[john f]

I'm going to try to avoid spewing flames at you, although it will be difficult.........

My response to you was carefully worded. You stated that the 12000K bulbs would not deliver enough usable PAR, and I believe you are wrong on this point.
What is your definition of "usable PAR"? The blue halide bulbs like the 20000k radium deliver a huge intensity spike which directly corresponds to the absorption maxima for 9 out of 11 zooxanthellae which occur in most sps corals. This spike is like 2-3 times the intensity of an Iwasaki within that range.
We don't know about the 12000k bulbs because to the best of my knowledge there has been no spectral distribution chart published on them.

I'm not here to get into a ****ing contest with anyone, especially a moderator, but you can not state with any authority that 12000k bulbs will not grow tridacna clams.
You have never tried it yourself and are depending on the opinions of others to back you up. When I present the view that it can be done and the clams can do very well and IMHO thrive, you shrug it of as an anecdote.
Bottom line..............PAR and "usable PAR" are not the same thing, and my contention is the 12000K bulbs have enough "usable PAR" to grow clams as well as any SPS corals you can grow.


John

[herefishiefishie]

How kind of you not to "spew flames" at me.

Look, you're misinterpereting me. I never said that 12000+K bulbs cannot deliver enough usable PAR. I said that I don't think that they deliver enough usable PAR (and I should have added "in the spectrum usable to clams") I said that in general it is not advisable to use them for clams (which are not SPS). If that was not clear, then perhaps I should have worded it more clearly. My mistake. [ADDED IN EDIT] Looking back at my previous post, I see that was indeed not clear in what I meant. I should have been more clear. Touche a moi.

You quote me as saying you cannot grow clams under 12000+K bulbs. You're wrong. First off, I would have used proper grammar and said "One cannot..." Secondly, I did not say any such thing at all. I said, again, that it is not advisable, not optimum.

Of course I am depending on the words of another. Knop has done his research, more than I ever could. I cannot simply rely on my own comparatively limited experience, nor does anyone else in his right mind. The entire scientific establishment builds on previously established research. No one "does it on his own."

Let me be clear about the point: I did not say that one can never have clams under 12000+K lights. I said that in general, it is not advisable. This is my experience, and also an assertion of Knop's. I'll take his word over yours, thanks.

Again (and again and again) I must say that the focus of marine organism husbandry should be to provide the OPTIMUM environment, not to explore the outer reaches of what's possible. I leave that to the experts who might not have any qualms about subjecting organisms to substandard conditions. My soft heart does not allow me to keep organisms under any but the best conditions I can give them.

I must assert that if more people in this hobby had this attitude, fewer animals would die. Rather, some of us kill many creatures in the exploration of the "possible."

[ADDED IN EDIT] I would like to point out that my being a moderator has nothing to do with anything. Just because I'm a moderator does not mean I cannot be gainsaid or disagreed with. Additionally, it also does not mean that I have any special authority or knowledge about clams. You subtly imply that because I am a moderator arguing with me might "get you in trouble." I resent that implication and assert that it is not true. As long as we're civil (even if we're a little fierce), there's no need for me to act as a moderator. That, of course, is up to you.

[john f]

OK, lets step back a bit.

Despite your obvious linguistic superiority :o , you are dancing around the issue.
Does Mr Knop have a spectral chart for a 12000k sunburst? If not any opinion of his in regards to the suitability of this bulb for clam keeping is based on anecdotal evidence.
Although understandably you hold his opinions in high regard (as do I), they are still opinions.
Lets get right to it shall we?

1. It is my understanding the zooxanthellae in tridacnid mantle are the same strains found in acropora and pocillopora. Is this incorrect?

2. If I am correct on #1, then the light absorption maxima for the pigments of these zooxanthellae should be the same in either pocillopora or T. maxima.

3. If 9 of the 11 pigments can best utilize light in the 450-480nm range then providing light of the greatest intensity possible within this range would be a good idea.

Please point me to the article Mr. Knop wrote regarding this issue so I can enlighten myself.

"This is my experience, and also an assertion of Knop's. I'll take his word over yours, thanks. "

Does this apply to all subjects or just clams?
Mr. Knop markets a foam fractionator which is not exactly world class but is marketed as such, trading on his good name.
Mr. Sprung markets Marine Snow which has a dubious nutritional value at best.
Should we accept everything these guys say above anyone else because they have good credentials, or should we examine each statement independently and have the facts chase the truth?

John

[herefishiefishie]

1. It is my understanding the zooxanthellae in tridacnid mantle are the same strains found in acropora and pocillopora. Is this incorrect?

It was my understanding that the opposite was/is true. I must admit I cannot remember where I heard, so I cannot be sure. You seem to be sure. Could you tell me where you got this information? (Like I said I do not remember where I got mine, so I'll just go with "I don't know."

2. If I am correct on #1, then the light absorption maxima for the pigments of these zooxanthellae should be the same in either pocillopora or T. maxima.

Not necessarily, but probably so. What other factors bear upon this? Does the material of the clam's mantle (the tissue itself) have an effect on how the light is absorbed? Also, the xooanthellae in clams are passed from parent to offspring throught the gametes if I am not mistaken, and are not shared with other species. Neither clams or SP corals are predators in the conventional sense of the word, so it is reasonable to assume that the zooxanthellae of the two groups have not intermixed (read: interbred) in millions of years at least, again if I am not mistaken. Therefore, as Great Danes and Jack Russel Terriers are exactly the same species, these zoxxanthellae might be the same species and yet require different spectra of light.

3. If 9 of the 11 pigments can best utilize light in the 450-480nm range then providing light of the greatest intensity possible within this range would be a good idea.

Certainly, as far as that goes.

Please point me to the article Mr. Knop wrote regarding this issue so I can enlighten myself.

See his book, "Giant Clams."

"This is my experience, and also an assertion of Knop's. I'll take his word over yours, thanks. " Does this apply to all subjects or just clams?

IMO, Just clams.

Mr. Knop markets a foam fractionator which is not exactly world class but is marketed as such, trading on his good name.

I have no experience with this skimmer. However, this means exactly squat. Stephen Hawking can't tie his shoes, but he's the world's foremost expert in astrophysics. Perhaps Knop is an expert with clams, but not a great marketer/designer of skimmers. Is this not possible?

Mr. Sprung markets Marine Snow which has a dubious nutritional value at best.

Agreed. However, I must ask what this has to do with Knop.

Should we accept everything these guys say above anyone else because they have good credentials, or should we examine each statement independently and have the facts chase the truth?

Don't be silly. I didn't imply this at all.

[john f]

Did a little more research:

Here is the famous table by Jeffrey and Haxo for pocillipora:

Absorption Spectra of Pigments
from Zooxanthellae of Poccillipora sp.
Jeffrey and Haxo 1968

Fraction Absorbtion
maxima Identification
1 Orange 428, 448, 475
ß-Carotene

2 Pale Orange 427, 450, 477
unknown

3 Yellow 425, 447, 476.5
Diadinoxanthin

4 Yellow 418, 441, 469
Dinoxanthin

5 Pale Yellow 408, 427, 455
unknown

6 Pale Yellow 420, 440, 465
Neo-dinoxanthin

7 Brick Red 475
Peridinin

8 Brick Red 465
Neo-peridinin

9 Pink Orange unknown

10 Blue Green 409, 428, 663 Chlorophyll a

11 Light Green 448, 584, 634 Chlorophyll c

Please note # 7 and #8, we will see these again soon..........

Percentage Composition of Carotenoids in Zooxanthellae from
Tridacna Crocea
Jeffrey and Haxo 1968

Fraction # Pigments % of Total Carotenoids

Tridacna Crocea
1. ß-Carotene 3.0


2 Unknown 1.5

3+4 Diadinoxanthin & Dinoxanthin 12.6

5 Unknown 1.3

6 Neo-dinoxanthin 3.1




7 + 8 Peridinin & Neo-peridinin 77.0


You can see that Peridinin and Neo-peridinin comprise 77% of the pigments found in these samples of T. crocea.

You can also note from the first table that these pigments at least in pocillipora have absorption maxima around 470nm. This is right smack in the middle of the huge intensity spikes we see with 20000k radium bulbs and I suspect the 12000k as well.
The Aqualine 10000K bulbs are also strong in this area.


Lastly, Great Danes and Jack Russells both require light of the same kelvin rating, and my Great Dane prefers 12000K :D

John