For clams 6.5k or 10k

[Omar H]

While I keep reading that clams need as much light as possible, I also read that they would do better if you don't keep them in anything over 10k. And it seems that 6.5k is better than 10k. Is this true? What are you using for clam tanks?

I ask this, because I made the analysis cost of running 3 MH w/ 6X55w and with 4X96w of PC, and found that the yearly operating cost is very similar, when considering and almost identical price for the 175w and 250w 6.5k (as seen on Hamilton's website), but with the difference in 10k's, the cost increase is more significant. At the end of the day, it continues to be in the $650 to $850 annual operating cost (electricity and replacement bulbs), sitll expensive. I guess we all know (or at least have an idea of how expensive this hobby can be).

The tank is 125g Nature's View.

Thanks for any thoughts on this:strooper:

[Potsy]

6500k mimics shallow water (a few meters deep)midday sunlight and ideally is the best "grow-out" spectrum. It certainly isn't necessary. If you do a search of member's setups, you'll find that there aren't that many reefers out there who use 6500 bulbs; they have a strong yellow tint that many find unattractive. Most seem to lean toward 10000K and higher and maintain wonderfully healthy clams. I keep a crocea, 2 maximas (one ultra colored), and a squamosa under 2x250 watt hqi (aquaspacelight with 13000k aqualine buschke double-ended bulbs) with only a 24 watt blue pc bulb for supplementation in my 75 gallon and they are doing fine and showing growth. And, the higher the kelvin rating on the bulb, the less necessary fluorescent actinic supplementation becomes so you save a bit on electrical costs.

[peterlin98]

Potsy,
I also use aquaspace light. Did yours come with 13000k aqualine buschke double-ended bulbs ? or did you replace them separately.
Thanks,
Peter

[Nicholas Ang]

T5 is the new kid on the block:mixed:

[Potsy]

Peterlin98:

My fixture came with the bulbs. They're labeled "Aqualine 10000" but apparently, according to vendors, their actual spectral output is 13,000k. Mine are a year old so I just ordered two more the other day.

[firechild]

I keep my clams (1 maxima and 5 squamosas) under 400W 6500K Iwasakis with fantastic results. I really don't think there is any advantage of 6500K vs 10,000K as long as the intensity is there.

[peterlin98]

Thanks Potsy.

Where did you buy the new bulbs? And have you changed the 24 watt PC actinic yet?
I like my Aquaspace light - but I wish the actinic setup is better. I think the light is too yellow.

Peter

[Jonovan02]

I don't know about its validity, but is a very interesting article:

http://www.animalnetwork.com/fish2/aqfm/1999/may/product/default.asp

[piercho]

And it seems that 6.5k is better than 10k. Is this true?
I guess it depends on what you mean by better. From my perspective, daylight bulbs (Iwasaki 6500K, Sunmaster CDX) are well distributed across the spectrum, and have good light output per watt. European 10KK (Ushio and AB) are not as well distributed across the spectrum as daylight bulbs, but still have good output per watt. Bluer bulbs (Venture 10KK, Coralife 20KK, Radium 20KK, ALS 12KK) have a peak output at 460 nm (blue), with less light output per watt compared to daylight bulbs and euro 10KKs.

People use all of the bulbs listed above, and others, to successfully keep clams. I use 250W iwasaki 6500K on my 24" deep (less 5" sandbed) tank, personally. Some people dislike these bulbs and consider the color yellow. If your water is yellowish, they will certainly show it more than some other bulbs. Between the euro 10KKs and Iwa 6500k, IMO, it is just matter of personal taste and budget. But I haven't used the 10KKs so I'm just speculating based on what I've read. There are people here who have kept clams under many different bulbs who would give better advice.

If you have Knopp's "Giant Clams", he gives recommendations on lighting (watts versus tank depth) for daylight bulbs, based on his experience. IMO these are pretty good recommendations, and would also be applicable for euro 10KK bulbs. For the bluer bulbs (which Knopp did not recommend when he wrote the book), you would use higher wattage bulbs to get as much light into the tank.

Sanjay Joshi has written a number of on-line articles on the output and spectra on MH bulbs, and the performance of reflectors. If you are interested in researching the empirical qualities of bulbs for reef use, doing a google search on Sanjay's name should get you to his articles.