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FAQs about Giant Clam Lighting Quality, Quantity, Duration

Related Articles: Got Tridacna? A beginner's guide to keeping Tridacnid clams by Laurie Smith, Example Chapter from NMA Reef Invertebrates book, on Giant Clams, Tridacnids, A Brief Guide to the Selection and Placement of Tridacnid Clams by Barry Neigut, Bivalves, Mollusks, Lighting Marine Invertebrates

Related FAQs: Tridacnid Lighting 1, Tridacnid Lighting 2, & FAQs on Tridacnid Lighting: Science/Application, Design/Fixtures, Lamps/Bulbs, Trouble/Fixing, Makes/Models/Manufacturers, & Tridacnid Identification, Tridacnid Selection, Tridacnid Compatibility, Tridacnid Systems, Tridacnid Placement, Tridacnid Feeding, Tridacnid Disease, Tridacnid Reproduction, Tridacnids 1, Tridacnids 2, Tridacnids 3, Tridacnids 4, Tridacnid Clam BusinessBivalves, Bivalves 2, Lighting Marine Invertebrates,


Clam Questions... Tridacnid lighting, fdg....     6/22/11
Hello to all! Christine K here, its been quite a while...please feel free to assume that it is because I have been staying out of trouble!
<Will do; have done so>
I am thinking about adding a blue maxima clam to my 90 gallon reef set up. I have been researching clam care and find that the information is not specific enough for me, so if you do not mind, I would like your most valued advice.
<Go ahead>
Recently, I have upgraded my lighting to 14K, 120W LEDs with a 423 par at 12 inches. They sit about 3 inches above my standard 90 gallon. As Maximas require "strong" light, is this considered strong enough?
My LFS indicated that this was pretty strong light, then shrugged when I asked if it was strong enough, and indicated that I might want to consider a crocea just to be sure. I was under the impression that Croceas were not as hardy??
Either way, they did not appear confident so I am leery of their information. What do you think? With that specific lighting, is a maxima is feasible, what would be the ideal placement?
<Some place on rock... likely at a foot or so in depth... Read here:
(low to medium placement depending on light seems to be the standard answer but I am looking for specifics with my current set up) Is once a week target feeding truly enough?
I feed Rods food, all my corals are thriving, what would be the best food to add to that diet to support a maxima clam in your opinion? Can you direct me to some further trustworthy reading?
<Yes; here: http://wetwebmedia.com/tridacfdgfaqs.htm
Additionally, I have added two Koralia powerheads on an adjustable wave timer to create
more natural water movement, rather than a single continuous stream. I believe this is more beneficial to filter feeders, and I would like to start adding some. I am hoping to eventually try my luck at a gorgonian again. A purple candelabra, since it is photosynthetic, I believe I will have better odds, I understand target feeding is still necessary.
Finally, I have been waiting patiently for almost a year for a deep water canary
damsel to come back in the market. I realize that they are rarely collected due to their depths, but this seems unusually long to me. Is there a specific season that I would be more apt to see them showing up online?
<Mmm, not as far as I'm aware. Just has to do w/ whom is out, collecting...>
Chris K

Could you help me shed some light on Par levels recommended for clams/Clam Lighting 5/10/10
<Hi Jonathan>
I was considering adding clams to my two reef systems. I happen to have an Apogee PAR meter handy and have taken some readings. I am scouring the net to see if I can find any guide for what levels are safe / recommended for the various species of Tridacna clams. Does anyone on the team have any idea?. I know its still not common place to ask for PAR.
<My feeling is that it's more important in our hobby to focus on lumens (light intensity) and Kelvin temperature. There are lamps that produce different levels of lumens and yet can have the same PAR value.
A 6000-8000K light generally will provide good PAR values for clams and corals but can have a slight yellow tint to them and is why many aquarists will supplement an actinic lamp to provide a more pleasing display.
Lamps with a Kelvin temperature of 10,000- 14000K generally provide a pleasing appearance without an actinic supplement.
Lamps with Kelvin temperatures over 14000K loose much of the important 700nm spike and should be avoided as the only light source for growing corals and clams. A PAR meter is a useful tool for determining Photosynthetically Active Radiation (PAR), but not very useful for measuring lumens (light intensity) which is more important provided proper Kelvin temperature lamps are used.>
I did find this post
Where the individual has listed the following;
Squamosa 200 - 300 PAR
Maxima 400 - 600 PAR
Croatia Up to 1200 PAR
<Yes, and makes sense as higher PAR values are found in shallower water where the red, yellow, and green spectrum is not
filtered out by the water but then the light intensity (lumens) is much higher in shallower water and is why I believe Kelvin temperature and light intensity are more important. When this is accomplished, PAR values should/will be in an acceptable range for photosynthetic animals.>
Would you agree with the previously stated? Any suggestions for Derasa or Gigas?
<Not for PAR values, but Kelvin temperature and light intensity are all easily found.>
I will share my PAR levels with you after I change the bulbs on my tanks as their current readings have gone down quite a bit, and need a good changing.
The first tank is 110 gallon with Coralife Aqualight Pro 150 (2 x 150 watt MH, supplemented with actinic pics and led moonlight). The second is a 48 gallon (46 x 22 x 10 3/4 ) with 4 x 54 T5 HO lighting suspended about a foot from the waters surface. Both tanks are open top It is fun to use a tool and see what level of light actual reaches the animals in both reef and planted aquariums. Hopefully more people will  use and lend a helping probe to other curious reefers. I have once or twice.
But the need to know if a number is high enough for ____ .is still present for me. Good tool for double checking nonstandard lighting situations, like my 'elevated T5', day LED builds, and possibly measuring window light entering a tank. I suspect I may be limited to Derasa on the T5 setup, and don't want to risk anything more needing unless I know for sure.
<Do not underestimate the intensity of T5 lighting. Many folks use T5's in shallow tanks and get great results in keeping Tridacna clams and corals.>
The MH setup should be adequate as long as Maxima and Croce are mounted on rocks closer to the
surface. Second opinion?
<All depends on the distance from the lamp(s) to the water's surface and the depth at which the clams are kept. Tank depths exceeding 24" generally require 250 watt halides for high light loving invertebrates.>
It is important to me to make a choice that will work for the long term.
<The PAR meter can be a useful tool for measuring lamp degradation but it should not be used as a tool for measuring light intensity. Have you read here?
Thanks for your input,
and listening to my ramble,
<You're welcome. James (Salty Dog)>

Re: Could you help me shed some light <Hee> on Par levels recommended for clams 5/11/10
Hmm interesting. I thought it was the other way around. That a Lux meter was most useful at determining if a bulb has become aged,
<The Lux Meter is usually used to measure illumination. The illumination is how level of a luminous flux is falling on a surface area. The luminous flux is visible component that is defined in radiant flux (light power/intensity).>
while a PAR Meter would allow you to 'see' how much light energy a coral could use for photosynthesis at a specific spot. Allowing to see if that spot would be suitable for what species of coral / clam, as far as lighting needs would go.
<I did/do not disagree here. PAR meters measure the photons in the usable spectrum for photosynthesis
in the range of 400-700 Nano meters. The 400-700nm is the optimal wavelength/color range for photosynthesis to occur. My statement was geared toward the use of a PAR meter to measure intensity.  Briefly, Lux is a measure of the light intensity as perceived by the human eye.>
As memory serves my par level on the t5 <T5> tank I <I> had previously mentioned was
about 140 PAR on the sand bed and 250 PAR on a elevated platform with my year old bulbs. On the halide tank (bulbs also about 1 year old) the sand bed also about the same, the tank is much taller. On the rock work in the halide tank I can get up to 400 - 500 PAR.
If for example If I <I> knew that a Crocea clam requires a level of 800 then my setup would be inadequate. Or more likely a person who has success with Crocea allows me to measure the light level at that particular spot by placing the probe next to the clam. I gain a number, a few more successful people letting me break in and probe their clam spots, I now have a range of good numbers / light levels for Crocea. The idea is all I would have to do would be to find a spot in the rock work that approaches that level for a final home for the clam, taking light acclimation into account to get 'em there safely Just to be clear I wasn't using any data listed on the box of the bulb for PAR. But using a meter, testing various spots.
Is your experience also of using this kind of meter? Were you suggesting to use LUX meter for the same purpose? No one else on the forum finds value in recording par levels taken in the reef tank using an Apogee PAR meter to confirm ideal placement of coral / clam? If so humor me, on what the par levels people have had success with clams. What not to go below.
<With today's technological advancements in aquarium lighting, the homework has been done for you. It is a matter of selection based on the animals you want to keep and tank depth/width.>
You mentioned aquarists should pay attention to color temperature and intensity. But I thought PAR was a measure of how intense light is in a given area on the sensor in the range that photosynthesis can occur.
<PAR meters measure the photons in a given area that are in the usable spectrum for photosynthesis in the range of 400-700 Nano meters. The 400-700nm is the optimal wavelength/color range for photosynthesis to occur. LUX meters measure light intensity falling on a given area. I know, can be confusing, but let's just leave it at that.>
Maybe I'm just being a numberholic, wanting to have a way to test and confirm everything. But you can see the method of my madness, right?
<Yes, and you may be torturing yourself. I prefer a much simpler method for modest size tanks; select the Kelvin temperature and wattage needed based on my tank depth and width and the light loving animals I
wish to keep. I have never entertained the thought of buying a LUX or PAR meter. I'm not implying
that they are useless, just never felt the need to invest in one or the other for my modest 60"x18"x18" reef. If I were building a custom aquarium in the several hundred gallon range, I would want to use one of these devices, or both, to ensure I have enough light falling on the corals/clams. And in that case, I would be looking for a PAR reading of around 300 on the substrate.>
Thanks for the reply, salty dog.
<You're welcome. James (Salty Dog)>
If I'm misunderstanding something please let me know, Jonathan

Nano Aquaria; General Care, Tridacnids and Coral  1/20/10
Hello again Crew!
<<Hello Carla.>>
First off, kudos for providing an amazing resource and service to all of us in the aquarium hobby, and thanks for all your help in the past!
<<Thanks, I hope to you meet your expectations this time around.>>
I have a 29 gal. nanoreef tank that is currently stocked with inverts and corals- Tridacna crocea clam, frogspawn coral, rose Palys polyps, lots of Shrooms, some Zoanthids, and "volunteer" polyps from the live rock.
Livestock includes one peppermint shrimp, a purplish serpent star, one Astrea snail, and a scary looking hitchhiker crab (have not been able to id yet, but has a purplish-maroon rather smooth carapace and eight hairy/spiky legs... he's very shy so I haven't been able to get a good picture yet- will move him to a future sump/refugium if possible when tank upgrades allow so I can add a small fish or two without worry in the future- would hate to issue
him a death sentence unprovoked, but don't trust 'em for sure).
<<Agreed, until an identification can be made I would best assume it to be like it's cousins'¦.opportunistic.>>
The tank has been set up for quite a few years, and since being moved in July, has finally settled down again- lots of denitrification bubbles in the sandbed and worms and 'pods aplenty.
A friend of ours recently upgraded his tank lighting, and gave us his previous setup for a very good price- the tank was previously lit with two 65W power compacts. The new fixture is a 250W MH (I know, overkill...
<<Not if you want soup'¦.I'm kidding'¦.only a little. Seriously though, make sure you monitor the temperature for large swings, keep the pendant elevated a minimum of 12' and have a fan running across the surface'¦am I'm sure you're doing this but for everyone else out there in WWM land, keep a close eye on the evaporation. Nanos can swing quick and when they do it's not pretty.>>
but I hope the clam will appreciate the extra light) with 4 24W T-5 actinic bulbs. We have the fixture suspended about 8" above the tank (with an extra fan on the light timer to dissipate heat)- the fixture has a glass cover, and the tank also has a glass cover.
<<I should have read ahead..bad habit of mine, sorry.>>
We have the actinics on a 12 hour cycle, with the halide coming on 1.5 hrs after those for 8 hrs/day.
<<With what you have, you could do with 6 hours a day.>>
I currently have a double layer of plastic window-screen on top of the tank to dim the light until the animals can acclimate... my question is, is this a good photoperiod for our tank?
<<See above.>>
How long should we wait before beginning to remove the covering, and what's the best way to go about this (cutting back to single layer, and then none for parts of the day? how long between stages?)?
<<I would leave up both layers for about a week to 10 days, then remove one layer, then wait another interval of a week and remove the last one.>>
I'd hate to lose any of the corals due to burning- the clam in particular I've had for 3+ years and is the star of the tank- I'm looking forward to seeing his true colors again- had developed a rather brownish (though highlighted by blues and greens) coloration due to inadequate lighting before. Also (and this predates the lighting change by a good bit), the clam produces a LOT of byssal threads- is this normal? Looks like a spider web floating at the base of the clam that trails of 4-6" in the water column... I have searched for images of other clams that display this
but haven't found any.
Is this cause for alarm, or just the sign of a healthy clam?
<<Depends on where the clam is set in the tank, T. Croceas unlike their cousins tend to exhibit much more of a boring behavior, and prefer/should be on a nice rocky surface.>>
One last question- there is quite a bit of coralline algae on the front tank glass- I haven't removed it because I'm hoping to encourage more coralline growth on the rockwork- would scraping it off with a razor help or hinder the spread of coralline in the rest of the tank?
<<Neither, feel free to clean.>>
I don't mind the look of it, too much... but would be nice to have an uninterrupted view of the tank if it won't affect (or will help seed) the rock growth. We switched to all RO water for top-ups and water changes, which has helped the persistent nuisance algae problem quite a bit (I suspect phosphates and silicates in the municipal water)- Yay!
Thanks again!
<<I'll be moving on to your additional mail now.>>
**Addendum sent by Carla before first reply**
Also... the mantle of the clam is about 5" from the top of the tank (in the center), the frogspawn halfway down (also central, but far enough from the clam to be out of sweeper reach), and the mushrooms are mostly in the bottom half to two-thirds of the tank (those in upper regions are growing parallel to the light source and get more indirect light)... if it helps/matters!
<<No, same as above, sounds okay.>>
(bet you haven't heard that one a million times... right)
<<I have to admit, I've been here since 2003, been on the fish forums since 1999 and was a livestock manager for 3 years, and a volunteer at a public aquarium for 2 years'¦..and I've never heard that one haha. Good luck -- Adam Jackson.>> 

Lighting for Maxima Clam How many hours per day of high intensity lighting does a 2-3 inch maxima clam need if it is placed in a 20 inch deep tank with 2-175W metal halide bulbs suspended 12 inches above the surface of the water? <<Probably not much more than eight... any more would probably be too much.>>

Lighting for Maxima Clam How many hours per day of high intensity lighting does a 2-3 inch maxima clam need if it is placed in a 20 inch deep tank with 2-175W metal halide bulbs suspended 12 inches above the surface of the water ? <9-10 hours would be appropriate. Maintain good water clarity (prevent yellowing) by small weekly changes of carbon rather than once monthly. Daily skimming and regular water changes too of course. Best regards, Anthony>

Clam lighting 9/28/04 Hello WWM Crew, Let me start by saying that I have read the FAQ about lighting and I came close to finding my answer.  I am purchasing a 60x24x24 150 gallon aquarium which will house various Clams and SPS corals.  The substrate will be 4 inches deep with a canopy of 12 inches. Lighting will be 2-250 watt MH 10k and 4-55 watt PC Blue Actinics for a total of 720 watts.  Will this be enough? <Plenty!  Absurd amounts of light are not required for most of these animals.  There isn't an Acro out there that needs more light than will be provided by the upper 1/3 of your tank close to the lights.  99% will do very well just about anywhere in the tank with that lighting.> Or should I swap out the PC's for another HM (750 total watts)  for the light intensity, PC's are at a distance.....possibly now 14k on the HM's for the blue that the PC's were going to supply......Thanks Steve  <IMO, adding more halide will only waste electricity and leave you with no where to put corals that won't tolerate very high light.  The PC's will be mostly for effect, so I wouldn't worry too much about the distance.  Best Regards.  AdamC.>

Clam Lighting Query Hello, Great time reading pages of FAQs, but still think I should inquire directly. To sweeten the deal I would like to tell you, that I believe you (all) to be entirely responsible for any success I may claim in the hobby. I have a successful (so far) 65 gallon reef system. The dimensions are 36"L x 18"W x 24"H. I have 175w 10K MH and 226(total)w PC. I have felt confident with the amount of lighting, until I began researching for the care of a 1" Maxima Clam I have just purchased. While I am fairly certain I can keep it in the top 1/3-1/2 of the aquarium, I am set on keeping it on the sand floor. -- Is the current set-up sufficient or will I, reluctantly, have to upgrade my lighting? If so what amount and variety would you recommend? Finally, if more is required what would you consider the most appropriate acclimation technique for a system that currently houses a number of photosynthetic inverts both soft and hard? Thank you very much, Jason Paul >>>Howdy Jason!   175 watts is not enough light for the more colorful Maximas - at least if you want it to retain it's vibrant colors. Tridacna maxima is actually a very adaptable species, but under inadequate lighting, they tend to lose their vibrancy. He should live and grow in your setup though, and I would recommend you place him in the top third of the tank. Also keep in mind that these animals are filter feeders throughout their lives, despite what you may read to the contrary. Add phyto every other day or so.   I've kept and grown T. Maximas with great success under 150 watt double ended fixtures, but those are brighter than your 175 watt single ended setup. Brown Maximas, or even T. squamosa should do fine with your light. Again, the blue ones will live, but it's not ideal. If you want a "can keep anything I want with no worries setup" go with a 250W double ended (HQI) fixture, or a 400 watt mogul setup. 20k looks better too, IMO.  If you upgrade, you can simply start the fixture fairly high off of the water, and lower it a bit each week until it's 10" or so above the water. Cheers Jim<<<

T. crocea Lighting and Placement  11/30/05 Hi, <Hi Dustin.> I have read though most of your articles and learned a ton of information for when I set up my next tank, but in the meantime, I have a few questions that I could not find answers to. <Ok.> I would like to purchase a T. Crocea Clam (~1-2'),  <I would go for one in the 2+ range maybe even a little larger.> and have a question about the lighting. I currently have a 40g tank, that is 36'x18' x 12' deep, with a 175w 14000k MH light 5' from the surface of the water, along with 3 -- 24w 6500k mini-PC's, and a 65w 50/50 ( ½ 10000K, ½ Actinic) PC. The MH is in the back-right side of the tank, the 3 mini-PCs are in the back-left side, and the PC is along the front of the tank. I leave the MH and mini-PCs on for 11 hours a day, and the PC on for 15.5 hours a day. I currently have 2 hammer frags under the MH and 4 candy coral frags under the mini-PCs. The hammers open up more than they did at my LFS, and the candy coral seems to be doing OK, although the heads aren't opening as much. <I don't think the lights or to blame for that, the PC's are efficient enough for this specimen, maybe water flow?> My questions are: 1) Is 14000k MH okay for a T. Crocea clam, or should I buy a 10000k replacement bulb? <I would rather see 10,000K for this specimen.> 2) Where would the best placement for this clam be (which area of the tank, and at what elevation)? I would be inclined to say at mid-depth under the MH, but I hear they need a more full spectrum (mixture of my bulbs). <I would place it in the rockwork, upper ½ of the tank as close to the MH bulb as possible. T. Crocea is the most light demanding of Tridacnids. Also as far as spectrum, most animals hosting zooxanthellae prefer Kelvin ratings of 6,500K to 10,000K. Actinics and bulbs in the 15,000K to 20,000K are mainly for aesthetics.> 3) Is my MH lights left on too long (11 hr/day) for this clam? (I read here that some people leave theirs on for 6-8 hours per day) <11 hours is a bit long, I won't say that it will hurt the clam but it is unnecessary.> <<Where did these clams evolve?  The equatorial tropics.  Anyone know what the photoperiod of equatorial regions is?  12 hours of light, 12 of dark.  The goal is to mimic natural conditions.  Marina>><Mmm, gets "dark" much quicker underwater than above... due to angles of refraction, and reflection. RMF> 4) What lighting is best for the candy coral? I have read that they do not like direct MH lighting, so I placed them under the mini-PCs, IYO, what is best? <There placement as far as lighting needs appears fine.> Thanks, and keep up the good work <You are welcome and thank you.> Dustin <Adam J.>

Clams and Overflow box question?    2/17/06 Good morning to you-      I love this site and have been using it faithfully for a year.  But alas...  I now need to ask a few questions.  I have had a 38 gal. tank for over a year.  I am now getting ready to build a 135 gal. 72L x 24W x 18H w/ a plenum and 3 in. LS, 155 lb. LR, 2000 gal. an hour filtration.  I have been reading all the articles on Clams and Lighting in reference to water depth, among others.  But I am not sure I can do what I am thinking (I may have missed something).  I would like to know if w/ a 520w Compact light (6700K/10000k, 420/460nm)  in 14 in. of water depth if a Tridacna Crocea would be happy and healthy or would I need to still have a MH? <Should work> Next...      I am planning on putting the skimmer box in my tank like in Anthony's diagram.  I am putting in 4 bulkheads 1.5 in. ea., the box will be 48 in.'s long centered.  I want to leave the sides open for water flow from the manifold around the top.  Is this enough bulkheads for the 2000 gal. rate of flow I want to get? <Should be, yes... If it were me/mine, I'd make two (the outside ones), 2" ID, put the bottoms near the same level as the 1 1/2"s> And will I get my flow rate if I use y connecters and plumb 2 an 2 together or should they be plumbed separately for better flow? <Can be linked together... need (likely) to be aspirated to speed flow, reduce noise and "bubbliness"> Thank You for your time-Deanna- <And you for your sharing. Bob Fenner>

- Crocea Clam Lighting and Quarantine 6/16/06 - Hi Crew, I looked through the FAQs on clams and lighting, but want to get a personalized opinion in this case, as they seem to vary a bit. I have a 12 gal NanoCube DX for my quarantine tank. It's got two 24W 50/50 PC lights, and I put in a colonized sponge filter, carbon, and a poly-filter. I plan to add a 3-4in T. crocea clam as its first inhabitant, which will then be moved to my display tank. I want to make sure the lighting and filtration in the quarantine is sufficient for such a clam. <The lighting is not... but if the clam is only passing through, then it really won't matter so much.> My intent was to elevate it so to be closer to the light, since they are not terribly bright. <Or strong/intense.> My display tank is 58gal with a 400W 20k MH. Will I have to photoacclimate the clam upon moving it to the display? <It won't hurt, but clams, unlike corals can close almost completely to get a break if they need it.> Thanks for any advice! Jason <Cheers, J -- >

Tridacna Crocea Lighting 2/5/08 Hey there! <Hello Jaime.> I have just recently bought a Tridacna crocea clam. I have a 40 gallon tank that's is about 14 inches deep. I'm running 2 36" 78 Watt T5HO's (10,000k daylight and 460nm actinic) I was wondering if this is sufficient lighting to keep a Tridacna crocea clam alive and healthy and if so how high up on the rock work should I put him? <You really need more light, perhaps another two or three bulbs in the 10,000K spectrum. I'd move him as close to the existing light as possible. Changing out the actinic for another daylight (10,000K) bulb would help, but will still be insufficient light for this clam.> Thanks for your help! --Jamie <I highly recommend you research all your future livestock wants and desires regarding their suitability/compatibility in your system. For more information on Tridacna clam lighting check out the FAQ's http://wetwebmedia.com/tridaclgtgfaqs.htm. Good luck, Scott V.>

Clam question, sys./lambda reading   3/12/08 Hi Crew, I need your in opinion as to whether or not I can get a clam. I have a 55 gallon FOWLR system running for almost 2 years now. It is 4 feet long and 18' deep with 1.5 inches of live sand/ <I'd increase the depth here... at least to four inches. See WWM re> aragonite with live rock. The current inhabitants are Magnificent Foxface, <Needs more room> Yellow tang, sleeper goby, cleaner shrimp, 5 Chromis <Ditto> and some turbo snails. We feed them Formula 2 flakes, Hikari frozen brine or mysis everyday and New Life Spectrum Sinking pellets/ Green Marine Algae occasionally. We have a protein skimmer, Fluval 404 for filtration and some powerheads. For lighting, we have Nova Extreme and it has 2 actinics 54 watt and 2 white 10 000k, also 54 watt. We also run 2 Corallife bulbs, one actinic <Switch these actinics out for more white> and one white 10 000k, both 28 watts. <Not enough light intensity for a Tridacnid> Both the Nova Extreme and Corallife run T-5 high output bulbs. The actinic bulbs go on 3 hours before the white ones and run for 7 hours in total simultaneously. We do 15- 20% water change bi-weekly with RO water and Kent sea salt. The salinity is set at 1.024, Ph= 8.4, ammonia is 0 - very low, nitrate=0, nitrite=0, phosphate =0, calcium = 450 ppm, temperature is about 74- 76 degrees Fahrenheit (winter) and 84-88 degrees Fahrenheit (summer). (Chiller is not an option due to budget....we use a fan during the summer) I have done some research and found out that T-5's can be used for clams also, and not only Metal halides, if placed high up on the rock work but want to make sure if it is true. <Marginally> If so, is it possible for our current tank condition to have an addition of either a Crocea or Maxima clam (only these two species found in LFS). If we are able to, do we need to add any other additives/ supplements or food for the clam other than doing water changes and the occasional use of Tropic Marin Bio- Calcium? Does the amount of time the light is on need to be increased? After reading, I am still confused about light acclimation. The clam at the LFS is exposed to metal halides, how do we get it to slowly adapt to t-5s? <Placing high up... in a system with more light than this> Thank you for your time! <Read here: http://wetwebmedia.com/marind5_5.htm the articles, FAQs files on Giant Clams. Bob Fenner>

Maxima Clam lighting and water flow 04/09/2008 Hello Crew, <<G'Morning, Andrew today>> Long time reader first time writer. I have been searching through the multitude of pages and information on the site, but have not found the specific information that I am looking for. I am currently running a 20H with a Rena XP2, Red Sea Wavemaster Pro running two MaxiJet 600's on the reef turbulent setting and a SeaClone 100 skimmer. I follow the GARF.org sites recommendations for supplements and have a good growth of coralline algae. <<Supplements? Which ones?>> In the tank I have assorted button and clove polyps, a bull's-eye mushroom, a devils hand leather , a cabbage leather, a feather duster, a branching torch coral, and an evergreen starburst polyp. I have two false Perculas, two black and white damsels and a yellow tang <<Yellow tang needs a bigger home, at least 75gallon>>. My clean up crew consists of 5 turbo Astrea snails, 5 scarlet hermits, 1 peppermint shrimp and a sand sifting star. I have 15 lbs of Fiji premium live rock from DrsFosterSmith.com arranged in a patch reef arrangement in the center of the tank with a minimum of two inches of clearance from the sides all the way around. The sand bed is 2" deep. I am running 2X65W PC's with 10,000k and Actinic and two blue moon led's. The photoperiod is 8a to 8p actinic, 9:30a to 6:30p white light, and led's all other. <<8 Hours of white light is more than adequate>> The tank has been running for seven months and the polyps have done amazing in spreading and all of the corals have new growth and open fully. I have ordered a maxima from ORA and would like to know where in the tank to place him and if my lighting is sufficient. <<In my opinion, your lighting is not sufficient to support a maxima clam as these are a more light intensive SP. Couple hundred watts of T5 or metal halides are more suited. Placement wise, place on the substrate to start with, while its getting used to a tank for a week, and then moved to a suitable location on the rockwork>> I have read that they do not like a lot of water flow and I want to ensure that it opens up and thrives. <<Clams, as a norm, do not like high flowing tanks, however, the maxima can tolerate this to a certain degree>> Thanks for listening (reading) my long winded dissertation. Dave <<Hope this helps Dave, Good luck in what you chose. A Nixon>>

Derasa Clam Lighting -- 04/10/08 Dear all knowing WWM crew, <<Eric here today'¦ Hardly 'all knowing''¦but I am learning more every day thanks to my association here at WWM! [grin] >> Your website is very helpful, and I have gotten many answers from it before. <<Ah, good>> I am hoping you can help with this question... <<Will try>> My tank is a 50 gallon reef, 48" long 13" wide 20" high. I have a 29 gallon sump/ fuge and an ASM G-1x skimmer. The tank is primarily LPS, and is lit by a 250-watt PFO HQI with a USHIO 20k bulb. Is this enough light for a Derasa clam? <<The short answer is, yes'¦ But even though Tridacna derasa is considered a lesser light-demanding species, it would benefit from some lighting in the 'longer' spectrums not provided by the 20K bulb (i.e. -- a lower a bulb with a lower Kelvin rating), in my opinion>> I had 2 65 watt PC actinics running before, but with the 20k, <<A lot of 'blue'>> I stopped using them. I was thinking of possibly using 50/50s or 10ks instead along with the 250. <<I would rather see this the other way around'¦use 10K for the higher output MH bulb, and supplement with Actinic fluorescent for reasons of personal aesthetics>> Would this be a good light addition, or am I fine without them? <<The clam will probably fine as is>> What is the best K rating for these clams? <<Lamps in the 10K range probably provide the overall 'best' spectrum sampling>> I do have a 14k if that would be better. <<Give it a try and see what the clam thinks>> I appreciate any and all input! Thanks, Jarod <<Happy to share. EricR>>

Yet another T5 lighting question 6/27/08 Good evening WWM crew. <Hi Jo Anne, Pufferpunk/Jeni here with you tonight.> I wrote a few days ago about my two maxima clams. Just a quick recap: We have had them for approximately 6 weeks. They seem to gape slightly after the lights have been on for about one hour. The tank is 125g Acrylic tank. (60X24X18 if I remember correctly) We currently have 4 80w T5, 2-10 or 11K AquaBlue and 2-Actinic plus. The brand of light is Giesemann. A. Nixon felt the problem was our lighting. Being they were under T5's at the store and from reading about the clams, I learned that although MH is preferred but T5's can work. I believe WWM's recommendation is 4w/gallon of light, which we fall short of. I want to remedy the situation and give these clams a fighting chance. Our tank was originally a FO tank, so it is in a cabinet with a matching wooden hood. My husband decided he wanted a reef tank and we've slowly made changes. I have since become what he calls obsessed with this tank. I am not sure how I could modify this for MH lights economically. I also am not sure I how I can jam at the least 500w of T5's as this would be the minimum to meet the 4w/gallon rule, without starting all over with lighting. (And possibly being served divorce papers) Any ideas? Also I read in Dana Riddle's book that T5's actually have higher PAR than MH. Is that true? If that is the case is can 500w of MH be compared to 500w T5 or PC for that matter. <It is my experience that T5s are just as good as MH. I am a big fan of T5s & keep clams & SPS under them. I do think you need more of them though. You need at least 1 Daylight bulb. I would think with a DIY kit, you should be able to fit several more bulbs under that canopy than 4. I have 6 bulbs over my 90g & probably room for 1 more. Be sure though that each bulb has an individual reflector above it.> One more quick question, I read that keeping the cover over the top of the aquarium also can decrease lighting. I would pull them but I do have a blue tang. I read they can be jumpy. I want to do what is best for my charges. <If you're speaking of a glass cover, then yes, remove it--the canopy should prevent your fish from jumping. Not only will it diffuse the light but it will cause your tank to overheat. You can screen in the open back of your canopy if you wish with nylon screening, although I haven't heard of tangs being common jumpers. Don't forget to dose calcium for the clams. ~PP> Thank you for your time, Jo Anne

Lighting for 120 gallon reef with clams 8/15/08 I am in the process of setting up a 120 (4' x 12" x 12"). I would like to keep clams. I have been looking at the Nova Extreme T5 lighting fixture with 8x54 W bulbs. Four of them are 10,000 K daylight bulbs, and the other four SlimPaq 460nm Actinic for a total of 432 W. <A nice fixture.> Will this be sufficient lighting to keep clams, and just about anything else in the line of coral that I may want to keep down the road? <Yes and no. It greatly depends on the individual species of clam/coral you wish to keep and where in your tank. Personally, I would swap out two of the actinics for 10000K bulbs. Having two vs. four actinics will not change your look too much. The nice thing about the fluorescent fixtures, T5 included, is that the placement of the actinics can have a huge impact. Placing the actinic bulbs at the front of the fixture will give the look that most want while allowing you to run the balance in daylight bulbs. Even then it will be a bit weak for a Crocea clam near the bottom, half way up or higher will be fine, where such a clam should be anyhow (on the rockwork). For the end all, be all lighting to keep the critter wherever you want I would think about adding a couple more bulbs.> Thank you for your help. Jeff
<Welcome, Scott V.>

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