Please visit our Sponsors
FAQs about Coral et al. Cnidarians System Lighting: Quality, Quantity & Duration

Related Articles: Coral Lighting: what we know and what we don't know (mostly the latter) by Sara Mavinkurve
Lighting Reef Systems: Considerations, Organisms, Goals and Costs by Bob FennerLight/Lighting For Marine Systems, Coral Feeding, LPS Corals, True or Stony Corals, Order Scleractinia, Propagation for Marine Aquarium Use

Related FAQs: Coral Lighting 1, Coral Lighting 2, Coral Lighting 3, Coral Lighting 4, & FAQs on Coral Lighting: Science/Application, Designs/Fixtures, Lamps/Bulbs, Night-Time, Troubleshooting/Fixing, Makes/Models/Manufacturers, & Lighting Marine Inverts 1, Lighting Marine Inverts 2, Lighting Marine Inverts 3, Lighting Marine Inverts 4, Lighting Marine Inverts 5, Lighting Marine Inverts 6, & LR Lighting, Fluorescent Light 1, Actinic Lighting, Compact Fluorescents, Metal Halide Lighting, Lighting Marine Invertebrates Growing Reef CoralsStony Coral IdentificationStony Coral Behavior,

An Acroporid in Borneo

Small Marine Aquariums
Book 1: Invertebrates, Algae
New Print and eBook on Amazon:
by Robert (Bob) Fenner
Small Marine Aquariums
ook 2: Fishes
New Print and eBook on Amazon: by Robert (Bob) Fenner
Small Marine Aquariums Book 3: Systems
New Print and eBook on Amazon:
by Robert (Bob) Fenner

Back in the game; lighting for a 75 reef       1/14/16
Hey Bob, we last spoke probably this time a year ago. Fiancé and I bought a house over the summer, needed the for the sharks, I mean attorneys, and had to sell my seahorses tank and fish only.
It's been 8 months, and I have been looking to get back with another tank, although on the cheaper side.
A friend of mine who I've helped with his tank over the years, nitrate issues, moving tank, changing rock out etc, has a 75 gallon tank at his office he no longer wants.
He wants to give it to me for free. He's awful with names, so he doesn't know what components it has or species it has other than "coral" and a purple tang.
I am assuming it has cheaper, off brand LEDs, which would be fine for low light stuff, but my goal is sps.
<I'd be checking (with a PAR, PUR meter).... am a cheapskate.... to see if the present LEDs would work>

I got a price on a t5/halide combo of 860 for 48 inch tank (yikes). So I found a local guy on Craigslist, who has a 48 inch Aquactinics , halide t5.
He wants 100 for it, not sure how old it is, but it works.
<Can only tell by.... testing>
Only issue I see is it has two halide bulbs, 400watts each, and it has two t5 bulbs. (Always thought you needed at least 4-6 t5 bulbs)
Is 400 overkill for a 75?
<IMO, yes; can be... will have to fight, adjust for heating>

I like the price, buy will it nuke the tank, and in your experience, how dangerous are halides in regards to fires etc?
<Can be trouble>
Thanks Bob, bob
<Welcome. Bob Fenner>
re: Back in the game       1/14/16

Thanks Bob. Just to further clarify, if I can save 700 by going with this 400 watt halide, would the only concern be heat?
<Mmm; no; not the only concern. Actually overdriving photosynthesis is more important; secondarily keeping up w/ testing/monitoring alkaline reserve, Ca, Mg.... >

I ask because the tank will be going into a finished basement, with central air, and on the hottest day this summer in August, the basement hit a high of 67.
<Mmm duo... expensive to pay to heat the air then cool it. IF it were me, mine, and I HAD to have/run MHs, I'd go w/ 250 watters.... IF it were me/mine I'd check the current fixture for utility. IF you measure 100 or more PAR or PUR at the depth you intend for SPS, I would stay/try this>
I understand the 75 is not deep, buy could I compensate by hanging the light 15 inches off the surface, as opposed to 7-8 inches?
<Helpful to some degree/s>
This light is obviously used , and is coming off an sps 90 gallon tank, which is 4 inches taller than the 75.
And just to clarify, you mentioned, "can only tell by..testing". The light def works from a electrical, mechanical standpoint (the four bulbs and fans etc)
<I meant bio. function wise; but yes>
If its more than a heat issue using this light, I will ditch it and wait for a 250 watt
to come along used. What makes the decision even tougher is the guy with the light lives 3 miles from me!
Thanks again Bob
<Welcome. B>
re: Back in the game       1/14/16

Thanks for that, makes all the sense in the world now.
I could use it, and hang it high, but your wasting heat and power and now have to subtract it with air conditioning. Never mind not being able to utilize the potential of the 400 and the stupid high electric bill.
Thanks for the explanation. I had a feeling, just needed it driven home
<Cheers, B>

Interpreting PAR readings       2/19/14
Dear Crew,
Thanks so much for your diligence and expertise! All aquarists should be grateful for all you've done for the hobby!
Just a brief question today. I was able to borrow an Apogee PAR meter from a friend. What an awesome tool (not to mention pricey)! I was just curious as to your thoughts on my readings.
I have a 6 foot 155 gallon SPS dominated reef lit by 3 Kessil LED 350's (90 watts each) and 4 ATI 80w T-5's. Reading are in PPF units (μmol m-2 s-1) (hope that you know more about these units then me!). All readings are with LED's at maximum.
950: Surface of tank (1" below water level) directly under Kessils at full strength.
750: 5" below water line directly under a Kessil (a large Porites cylindrica resides here)
550: 5" below water line, 6" away from Kessil (a small tabling Acropora is here).
300: 5" below directly under T-5's. (Several Hammer corals are here.)
90-200: Bottom 3" of tank at various locations (various LPS here as well as a Bubble-tip Anemone).
 <About what I'd expect readings-wise here. Some SPS folks keep need/can use more, but most all Cnidarians hobbyists keep can get by to do well on about 100...>

All corals are surviving and many are growing. I was just curious if these reading seem to be too high or low. Not many hobbyists in my area are able to measure PAR so it makes it difficult to use these numbers in terms of drawing comparisons.
Wichita, KS
<There are some folks (Sanjay Joshi and Dana Riddle mostly in English writing) who have tried over the years to enlighten (I could've written thrown light on... groan) the public re lamps, fixtures, esp. reflectors and such readings as PAR, PUR at depth... Do realize that most all photosynthetic life has "adaptive capacity" and often "other sources of nutrition"... Oh, and that photo-duration and other factors such as water clarity do come into play, at times significantly... Bob Fenner>

question number 2 for the day: photoperiod    8/31/11
Alright, guys and gals, here's one that I know everybody has an opinion on: I'm trying to figure out my optimal photoperiod. I have a mixed reef with only a handful of coral (one large frag/small colony of Stylophora in the tank for about 6 weeks, a Trachyphyllia geoffroyi, and a smattering of polyps--which are kept down-current and far away from the SPS and LPS, and have not shown any signs of bothering them thus far). I also have a BTA to round out the photosynthetic inhabitants.
<I do hope it/this gets along (and doesn't wander amongst) your Scleractinians>
The SPS is in an area with about 280-300 PAR, the LPS around 120, and the BTA around the 150-170 mark.
My lighting system is a custom LED setup, so I am currently running 12 hours of actinics and 10 hours of full lighting without needing to worry about heat (as of yet, no controller to take advantage of their dimming feature).
<Also fine>
Since purchase, the anemone and LPS have done very well under the current lighting (which was changed about 7 weeks ago from a 10 daylight/8 actinic schedule; however, the BTA is now less red and closer to an orange/beige).
<... could be foods/feeding... or negative interaction/allelopathy at play here>
The SPS has grown, mostly in the way of producing more "buds" forming on the main branches. Though it began as a mostly cream/soft pink hue, it is now more vividly pink. My own research into photoperiod recommendations have resulted mainly in opinions about MHs, as LEDs are still far from the norm in tanks. Oh, and despite the amount of time the lights are on, I have not had any serious algae outbreaks since upgrading from PC lighting 3 months ago.
<Lack of algae likely a nutrient/limitation control>
Any thoughts?
<Have posted, given talks for decades re... Most petfish and public aquarium systems are overlit intensity wise... FAR more so than the wild... where due to angle/attenuation of sunlight, it's rarely as bright except for calm days, w/ little cloud cover, when the sun is about directly overhead... Any PAR value near 100 will "do" for the intents/purposes of hobbyists... Over-driving photosynthesis has its definite downsides and MANY systems/organisms in captive care are past photo-adaptation at times; MANY systems/organisms suffer for lack of "some other" aspect than photonic energy. 'Nuff said? Bob Fenner>
re: question number 2 for the day: photoperiod    8/31/11

Thanks for the quick response, I know you're pretty busy right now with the Smiths.
<Ah yes... all hours, except pool time at nights while we're here in Lautoka... hope my liver holds up>
I suppose I should have been more direct, but my question concerning my photoperiod was actually if I might see better results by cutting it down by a couple of hours.
<Likely not much difference, but worth examining. How will you measure "better results"?>
I've read that beyond a certain point, photosynthetic marine life becomes "exhaustive" from the process, and any additional light is not only wasted, but possibly detrimental.
How say you on this?
<This is so>
It seems to make sense, but sounds less like it would apply to my moderate setup and more to those aquarists with hundreds of watts of MH.
<Much written on the topic, available on the Net... Do search for the names Sanjay Joshi and Dana Riddle re. BobF>
re: question number 2 for the day: photoperiod     8/31/11

I will certainly check out those sources. And on the question of what I mean by "better results"...hmm, I actually had to think about that for a second. Vivid coloration may be pleasing to my eye, but this is a purely aesthetic concern. I suppose I would want to see anything that indicates good health in my corals: fully extended polyps, no bleaching, noticeable (if slow) growth, etc. The Stylophora is by far my favorite frag, so I'd love to see it spread well, but alas, I learned post-purchase that it tends to be a slower growing coral. Ah, well, at least it's something I can bequeath to my son someday.
<Sounds good>
Anyhow, safe travels, and may your liver hold no grudge.
<Thank you Dustin. BobF>

Question regarding lighting on new 60G reef/Reef Lighting 8/8/11
<Hello Gordon>
I am currently in the process of getting parts together to upgrade my current Nano reef to a larger tank. I am currently running a JBJ 28G Nano Cube with the 89W LED light setup and I am rather dissatisfied with the results I am getting out of the lights, which is another subject in itself but a main factor in not considering LEDs on the 60G build. I currently have a few Zoanthid colonies and LPS consisting of Frogspawn, Green Star Polyps, Torch and a Duncan in the Nano Cube, most of which are slightly faded or don't show the same color they used to. Anyway, the 60G tank is 48"L x 15"W x 17"T, will be run without a canopy, open-topped and filtered with 25G sump with additional flow supplemented by either an MP10 or MP40.
<Go with the MP40.>
I have narrowed down my lighting choices, but I am still having a hard time deciding between going with a 36" 6-bulb T5 setup, 48" 6-bulb T5 setup, a 36" 150W MH/2xT5 setup or a 48" 2x150W MH/2xT5 setup. The MH bulbs would most likely be Radium 20,000Ks supplemented by some blue or purple T5s. Either setup will have some sort of moonlight LEDs added in, so I haven't factored in moonlighting as a capability, just an added benefit if the fixture comes with it.
The reason I am considering the 36" units is so I can have lower-light zones on the end of the tank without worrying about how high I place my corals in the tank if I were to have a full-length unit. My goal with the tank is to have great color definition in all of my LPS and have enough light to add a few clams and SPS later down the line. I have been having a hard time trying to figure out what would best light this tank and have been unsuccessful in finding any reason why one choice would significantly degrade my ability to keep clams and SPS throughout the tank, so I was hoping you could give me some insight here that may make me see something which was not previously factored in. Obviously, heat generated by the MHs are a definite weakness and I want to avoid any additional heat which would require me to add a chiller, but I don't know if a MH/T5 fixture hung over the tank would produce enough heat to warrant a chiller.
<Would all depend on the ambient room temperature. With your tank size, I'd consider a 48" six lamp T5 fixture. This will provide enough intensity for SPS/LPS and some Tridacna clam species. Additional color pop can be provided by some Ecoxotic Stunner LED strips which will also give you the shimmer effect. These units are very compact with a width/height of only .5 inches. The adhesive mounting which is included will allow mounting in most hoods.
Take a look here.
Thanks for the help.
<You're welcome. James (Salty Dog)>

Lighting question along with "what are these things?"   8/7/11
<Hello Darrel>
First off, thanks again for all you do.
<Thank you>
I hope it doesn't get tiring hearing how much all of us appreciate your expert help. It makes this hobby more enjoyable when we know we're doing it right, or at least have some place to come to learn and correct what we were doing wrong.
<I agree>
My own knowledge is light years ahead of where it was before I found your site (and bought and read Bob's book!). So, a big THANK YOU to the whole crew. :-)
<I'm sure they/ we all appreciate your gratitude, thank you>
Onto my questions...
Reviewing the FAQs, I see that 1-2 watts/gallon is about right for live rock (assuming you want coralline growth), and 3-4 watts/gallon is about right for corals.
<Mmm, I am not a fan of these 'rules of thumb' personally>
My current tank is 75 gallons, 48" long x 18" wide x 20" deep/tall.
<A narrow, deep tank, thus my earlier statement>
My lighting, I'm told, is 96W of power compact with a 34" bulb and half the bulb being 10,000k and the other half being actinic (450nm),
<So only really 48 watts of useable light. Again...>
but I'm not seeing any coralline growth. Maybe I'm not waiting long enough?
<This lighting is inadequate. You will see coralline growth, but it will be v. slow>
Are the rocks too far down in the tank? They all occupy the bottom half right now.
I started adding live rock 3 months ago. If I had a patch about a half inch by a half inch, how long would it take that to become an inch x inch, assuming good conditions?
<Depends on the species, but some can grow rapidly, days, weeks. Not months.>
My tested parameters are:
pH = 8.3
Ammonia = 0
Nitrite = 0
Nitrate = <2.5
CA = 460
dKH = 11
PO4 = 2.0
<Too high>
MG = 1650 <- does this seem overly high? I'm not adding anything to make it so.
<Yes, I would check your test kit against another. Take some water to your LFS for testing>
SG = 1.024
<I would raise this one notch>
Temp 25C
<Apart from the Mg & PO4 these parameters seem pretty good to me. High phosphate inhibits calcification though, in both corals and coralline algae. Look this up : http://reefkeeping.com/issues/2006-09/rhf/index.php you need to reduce it>
96W 10,000k/actinic
<This lighting is inadequate>
Maybe 40 lbs of live rock so far - will be adding more <I would buy the amount of live rock that makes your system look how you want it to look rather than to achieve any rule of thumb you might have read>
Also, my hood has a place for another 4-pin PC bulb like the first, and that would give me 96x2 = 192W, or 192/75 = 2.65watts/gallon.
<This would be better, if you do then go for an all-white 10K bulb. You could look to retro-fitting T5 lights here instead for better results. 4 x  39W bulbs should do the trick, three white one blue>
I do have 1/4" acrylic between the light and the water, and the light is about 4" from the water itself.
<Ok. You could lower these a couple of inches, possibly utilising some fans somewhere if the plastic starts to bow with the heat>
Is that sufficient for some of the corals and anemones (excluding Aiptasia!), or do I need to get even more light before
considering those animals? Maybe I need to do a search on non-photosynthetic corals and anemones?
<These are difficult to keep. I would stick with the trusted and tried until you are more comfortable>
When I run just the one 50/50 bulb, the bulb is warm, but not hot. When I plug in the other bulb to try to run them both, both bulbs get quite hot (I guess about as hot as a regular incandescent would) and will actually warm
the water. Is that consistent with what you know about PC lighting?
<All lighting will do this to an extent>
There are currently no fans to move the heat, so if I want to plug in the
bulb (which I think I do), I'll need to retrofit some fans or something to blow the heat out,
<Ahh! I did elude to this earlier>
but I don't want to spend time doing that if the behavior is indicative of a problem - I'd rather just limp along on one warm 96W bulb until I can afford new lighting. Of course, if that behavior
is normal, I'll start looking into installing some fans.
<I would, and plug in the other bulb>
<Ok, before we get to this one I have one more suggestion for you: Purchase a couple of pieces of live rock with really good coralline growth on already, perhaps some second-hand that has been in a reef tank for some time to 'seed' your tank>
I've got some things in my tank that hitchhiked on my live rock and I'd like to know what they are.
<These look like Majano Anemones to me http://www.wetwebmedia.com/anemoniafaqs.htm?h=>
I looked at all the pics on the LR ID pages, and the closest I see is the one on page 12 (LRID12) that describes a possible Zoanthid, but when I go to the page referenced there, nothing there looks like what I have, so I don't think it's that. They're cool looking,
and most of them seem to be doing well, but one I have on another rock is not fully extending like the others are. It seems to not be as healthy, I guess. Do those have any special needs, or can I assume that whatever I'm providing is correct because the other two dozen or so of these that I have
seem happy?
<If these are Majano then they are considered a pest. They will sting corals, but are otherwise pretty harmless. Some people like them, they are attractive, but having a plague of them is not generally considered to be a good thing>
Most are small, like maybe 1/4" across. Note that the happy ones are all on one rock, while the less happy one is by itself on another near by at about the same height. I'm providing a picture of the largest one, which was torn when I got it, but has repaired itself quite nicely and is just over half an inch tall.
Side note - thanks for turning me on to live rock! I find it extremely interesting and I actually spend more time looking at it than I do my actual fish. LOL! It's just fascinating stuff. :-)
<Heee! This hobby can make geeks of all of us sometimes! Welcome to the club!>
Thanks again, and I eagerly await your answers.
<No Problem>
<Simon><<Look more like Mushrooms, Corallimorpharians to me. RMF>>

Re: More: re: (reef) Lighting question along with "what are these things?"   8/8/11
Awesome. I was going to ask for a second opinion as none of the Majano pictures I've seen look very much like what I have given that the Majano pics I've seen show tentacles, not little knobby things. Looking at the mushrooms, these seem much more likely to me. I'll study up and figure out what to provide for them, though they actually seem to be quite happy with my inadequately lit tank.
<There is a wide range of use w/ many Cnidarian groups... ability to use other sources of nutrition>
I do plan to follow the advice and ramp up the lighting. I didn't want to increase lighting without knowing the answers to my questions, but now that I have what I need, I'll kick that into gear.
I'll also see what I can do about eliminating the phosphates and will read up on the link you kindly provided. I wasn't sure how big a deal those were given the apparently adequate other tested values.
The test kit I used for the Mg is a brand-new ELOS test kit, and I did the test twice. I'll take some water to my LFS and have them test, though.
If it does come back that it's that high, is that a big concern? What's my target, maybe 1350-1400?
<W/in reason there's no worry>
So the specific gravity range that I've seen is from 1.022 to 1.024 - you're saying I should have it at 1.025?
<Yes... see WWM re: http://wetwebmedia.com/spg_salinity.htm and the linked files above>
I just want to make sure I understand fully.
Thanks so much for your help; it's truly appreciated.
Darrel Owen
<Welcome. Bob Fenner>

Watts Per Gallon 9/3/10
Had a question on the Watts per Gallon rule. I've had a 30 gallon tank setup for quite a while with a few corals, Heteroxenia and such, along with a few anemones. The anemones are a Haitian and bubble tip.
<It is not going to work well in the long run mixing these two in a system this size. It is a bit on the small side for even one.>
I've just recently heard of the watts per gallon rule that i should have at least 4 watts per gallon.
<This is a widespread, but poor rule of thumb. These need a certain lighting intensity, increasing or decreasing the water volume around the organisms does not change this.>
The Corals and Anemone's in my tank I've had for a little over a year now and they're doing quite well. The Lighting I have is a T5 strip with 2x 14 Watt 10000k lights and I have a one strip Actinic. I wanted to know if I'm in any danger of losing anything, or if the watts per gallon rule is more of a guide line.
<It is a very loose guideline. That being said, your light is nowhere near adequate. See:
and the linked files above.>
Thank you for your time.
<Welcome, Scott V.> 

Color Spectrum in Reef Lighting  1/20/10
I need some help on SPS lighting.
<<Hello Terrence, first off I'd like to apologize for the lateness of our reply, typically we answer all emails within 24 hours if not sooner but every now and then they slip through the cracks. I hope this response finds your animals healthy and well and that it is still of some use to you.>>
I have a standard 75g tank with 250w 10k bulbs.
<<How many? I'll assume (which is dangerous, that you are running two.>>
I intend to keep Acro. and Monti. in the tank and have recently added my first Acro. corals to the tank. I ordered them from Live Aquaria's Divers Den. In my tank they look brown. I noticed that they keep there frags in 20k lighting.
<<Of course they do, they look better and sale better under the bluer lights.>>
Should I change my bulbs to 20k to get the color I see the coral when I buy it. I notice a trend for Wet Web Media to suggest 10k lights however every tank I see that has good coloring in there SPS corals are kept at 20k. Would I reach the point of diminishing returns with the 250w 20k at 20" deep or would I have enough light at the bottom to keep Monti. corals and lower light Acro. ? I know its a balance of usable light vs. aesthetics but I cannot fathom keeping a tank full of brown just to get good growth.
<<We do tend to recommend 6,500k to 10,000k lights for zooxanthellae hosting creatures, because they are the most common and closest available lights which match the spectrum of sunlight that you would find on a coral reef. 6,500k is actually closer, and 10,000k is somewhat of a compromise because of aesthetics. Now as you have noticed some folks prefer the bluer spectrum, in which case I would recommend supplementing your halides with a fluorescent lighting system around 20,000k. If the only option for you is to switch your Halide bulbs, I wouldn't go all the way for 20k, I would compromise at 14k.>>
Thanks in advance for your input.
<<Good luck, and I hope this helps -- Here are a few articles I would also suggest;
Check out the latter for in depth technical details, by Dr. Sanjay Joshi he is the 'lighting' authority in my book.
Adam J.>>  

Lighting question 01/14/09
would I need new lighting?
Would I benefit switching to halide or not?
My tank is L79"XH24"XW21" have a sand bed of about 2" to 3" currently I have 2 T8 TL lights 32W and one blue light TL and quit some day light from outside reaches my tank.
stock list
- 5 leather Toadstool
- 1 green Goniopora
- 2 clams
- 1 green hammer coral
- several mushrooms brown and green
- green Zoas
- 2 magnifica anemones
- 7 feather dusters
- 1 red cauliflower coral
<The clams and anemones could likely benefit from more lighting.>
I believe most of my corals are doing quit ok but maybe could do better with different light?
<More likely, a sudden change in lighting would hurt more animals than it helps here. Metal halides are intense.>
can you guys tell me what the advantages are or disadvantages of going to higher lighting?
Halide or T5?
<This is really something you're going to have to read about and decide for yourself because there's no one right answer. Please see here:
not really educated about lights
Sara M.>
re: Lighting question 01/15/09
a lot to read about.
I did check my lights and found the following information.
They are
2X 36W T8 965 12000K silver light
1X 40W blue moon
so if I read up well 12000K is equal to blue skies day light which I think is good?
<Well, no... natural sunlight is actually <6000K, but that would make one "ugly" aquarium bulb. I think 12000K is fine though.>
Now second? do I need to leave the blue moon light on together with my 2 silver lights or does that make no sense at all? or does it help?
<"Blue," "silver," (actinic), etc. bulbs are going to be mostly for aesthetics (and/or for dawn/dust lighting). Again, most of this is just personal preference. In reef keeping, generally, I go by the wisdom of "if it ain't broke, don't fix it." If your animals are doing well and you're happy with the way everything looks, I'd just be happy with what you have.
Sara M.>

Lux Meter 8/21/09
Hi Crew:
<Hello Bonnie.>
Have a quick question regarding Lux meters. I am thinking about purchasing the Lux Light Meter put out by Milwaukee Instruments. Have any of you had any experience with this brand Lux meter?
<I own, have used this unit.>
If this is not a reliable brand, could you recommend one please. Many thanks as always.
<It works fine for the purposes of a home aquarist. As I said I had bought one a while back, and would again should I find myself in the market.
Welcome, Scott V.>

Coral Glue And Coral Light Absorption (Photoperiod) -- 04/12/08 Awhile ago I got a couple of corals that came with a silicone type glue that mounted them to the rock. At the time, I didn't think it would be so good and don't recall where I got these corals. This glue bonds to rock just by placing it on top of it. I have tried to locate this material at all the tropical shops in my area but no one carries it or knows what it is. It is not "super glue" or putty - it stays flexible and doesn't need to be reapplied. Can you help? What is it and where can I get it? <<I can only guess, but there are some better 'underwater epoxies' that remain flexible. These products form a molecular bond that is quite tenacious. They're quite pricey too'¦at around $50 per quart>> On the coral's light absorption - how many hours of light do they really need daily using optimum lighting? <<'Optimum lighting' will vary by species'¦but lighting in the tropics where most all specimens we strive to keep hail from averages a bit more than 12-hours per day'¦and at an intensity we can only dream of replicating>> Does it vary by type of coral? <<Indeed>> I have polyp types, leathers, frogspawns, elegance and coral plates. Thank you. <<I suggest you provide a lighting period of somewhere between 10 and 14 hours per day'¦depending on quality/intensity of the lighting. EricR>>

Is My Normal Output Fluorescent Lighting Suitable for Anemone and Corals? (The Short Answer Is'¦No) -- 02/12/08 Hello, <<Hiya, Joan!>> I read and then reread your article on lighting. <<And?...>> I have used Vita-Lites for many many years and thought they would be fine for my introduction of inverts, an anemone to start with, and maybe a coral or two. <<Mmm, you will need to be more specific than 'a coral or two''¦and some specifics about your tank would be a big help too...oh, and do read up on our site re anemone systems/mixing with sessile inverts (not recommended). As for the Vita-Lites'¦these are a great 'daylight' spectrum fluorescent bulb, but being a NO (Normal Output) bulb you need a fair number of them over the tank, with actual 'numbers' depending on the light-requirements of the organisms you plan to keep. And while it is possible to keep some coral species under NO fluorescent lighting (I did so back in the late-eighties and early-nineties), I don't recommend this for keeping Anemones>> The Fish Store says No, I need MORE. <<Without more information/detail re your system and its proposed inhabitants, I must agree'¦and I certainly do where the Anemone is concerned>> I.e. 10K etc and recommend the Coralife compacts. <<You don't 'need' 10K bulbs; these are usually suggested because they provide a 'balance' between what is suitable for/useable to the photosynthetic organisms and what is pleasing to the human eye. In fact, if you like or prefer a lower Kelvin temperature (e.g. -- 5500K -- 6500K), these will generally provide a better output/PAR rating watt-for-watt than the higher Kelvin temperature bulbs. A mix of 10K and 6.5K bulbs provides far more intensity, as well as light in the more 'useful' wavelengths, than a mix of 10K and Actinic bulbs>> I am sure they are great, but do I really need that much light? <<The answer here likely is, yes'¦I am doubtful your NO fluorescent bulbs will support an anemone>> Especially when a retrofit is $200+ on sale. <<Unfortunately, the price of lighting suitable for keeping many/most of the reef-associated photosynthetic organisms often proves to be as much as one-third the cost of the entire reef system. If you do decide to upgrade, I would like to recommend T5 fluorescent lighting over the PC fluorescent lighting. Not that the PCs can't work, but the T5 is better technology in my opinion, and has greater bulb selection/allows more flexibility over the PCs. The smaller size of the T5s will also allow more bulbs to be fitted/placed over any given tank size>> Please drop me a short note with your ideas. <<You have my thoughts'¦do write me back if you wish to discuss further>> Joan in Seattle <<Regards, EricR in Columbia>>

Reef Lighting and Kelvin Ratings 10/27/05 Hello and thank you in advance for your needed help! <Hi Jon, and umm'¦your welcome in advance.> I am currently thinking of expanding my horizons of aquarium size and have a lighting dilemma. The tank that I am getting is 180 gallons which is 72x24x24. On my current tank I am running one 10k 250w AB HQI with VHO actinic. My livestock is a mixed garden (including SPS and clams) to say the very least.  <Ok, so a shallow water biotope.> My questions are the following: would one more equal halide fixture be sufficient on a tank that size; or would three be better?  <Three is the recommended number if you want to continue with the SPS and Clams. One bulb per 24' of tank length is a general recommendation.>  Also I am considering moving from 10k to 20k (also in the AB line of products) in order to achieve a bluish white color. Would my mixed garden corals suffer from this regiment of lighting; or should I remain on the path that I am currently following?  <Mmm, photosynthetic animals prefer lighting in the 6.5K to 10K spectrum so out of three of your bulbs I wouldn't go all 20K. 14K at the most, but honestly 10K with VHO actinic supplementation is the best way to go in my opinion. Maybe you could mix bulbs, a 20K on the middle with 10K on the ends. Its your choice in the end, and you probably could get away with 20K but some animals may have to be left out and expect slower growth.>  Do you have any further suggestions of how I can achieve the 'look' for my aquarium that I am seeking? <Just the above.> Thank you very much for your time and expertise. It is greatly appreciated! Respectfully, Jon <You are welcome, Adam J.> 

Re: Reef Lighting, Kelvin Ratings Hi Adam J, <Hello again.> In response to my question (see below) on PC lighting you indicated that I should replace one of my Dual Actinic so as to get 3:1 ratio. <Yes that's right, with your current lighting set-up and considering the photosynthetic animals you are targeting I would not use more than one full actinic bulb.> (I currently have 2 65Watt Dual Actinic and 2 65watt Dual Daylight). I was wondering the reason behind that <Photosynthetic animals generally prefer lighting in the 6500K to 10,000K spectrum.> but apart from that what type of PC should I replace it with i.e. 6700K, 7100K or another Dual Daylight (6700K & 10000K). <Either of those sounds fine.> Finally can I still achieve the 3:1 ratio by replacing both Dual Actinic and with 2 Actinic/10000K bulbs. <That would probably be fine as well.> I want the remaining actinic to be spread evenly throughout the aquarium. <I understand.> Many Thanks <You are welcome.> PS: You all - Bob, James, Adam, Marian (sp), <<Marina.  -SCF>> Anthony, Blundell, Ali, Eric etc. do a FANTASTIC  service for hobbyists and the industry as a whole. I know I would be lost  without your free expert opinions. Much Kudos to ALL of you - Happy Holidays! <We all thank you for compliments and hope that your holiday is joyous as well, Adam J.>

Light for Coral in Quarantine - 8/15/03 Thanks for the help in advance.  I have read with diligence the info concerning quarantining corals and invertebrates.  Great idea!   <yes... very necessary to prevent the introduction of pests, parasites, and diseases> Read about lighting, but have a concern.  Some distributors of corals make (SPS especially) make an effort to tell you about their lighting system and how the corals need specific intensity.  Some even go to the effort of suggesting locations in term of depth to light.   It is very helpful that they share the params under which they grew their product> How can you replicate this in the quarantine tank by normal florescent lighting? <easily my friend... do realize that the PAR of many fluorescent lights in 4-10" of a shallow QT tank (say 10 or 20 gall) can easily compare to that of a MH at depth (12-24"). Most MHs can only deliver 25% or less light read at the surface to the bottom third of the aquarium. And even in cases where you cannot meet the arbitrary high standards of the source, know that QT is not at all about matching these params. Cnidarians can easily be fed to compensate for a lack of lighting (as in QT)... interestingly, the reverse is not true. You cannot make up for a lack of food with extra lights (as some SPS maniacs with 400 and 1000 watt halides seem to think). Corals feed by absorption or organismally. Discover which yours responds to easier and simply kept it fed well under moderate lighting in QT. No worries about color changes... they will come back under bright light. Its just as well, since even bright light corals must suffer the darkness of extended transit for delivery. In some cases, resumed bright lights would be stressful. Great question... best regards, Anthony>

Lighting Hi guys! I have another question as usual. When I want to purchase a coral for my tank, I look to see if I can meet it's lighting requirements. How many watts of light is "low light" or "medium light" or "high light?"  <there is no hard and fast rule about it... all depends on water depth and lamp intensity. Still... halides over shallow water (24" or less) is high light. VHO or PC over 24" or less medium. NO under almost any circumstance is low light> I have a 120 reef tank with 220 watts of PC and 80 watts of NO. Is this considered low to medium?  <agreed> Right now I have a colt coral, some yellow colony anemones, a few different mushrooms, and a bubble tip anemone. Everything seems to be happy. Sometimes I wonder if the BTA has enough light.  <also agree and a little weak for the colt to. You are feeding the colt phytoplankton? If not, scrape algae off glass often, consider a seagrass refugium and some form of phyto feeding (phyto reactor or properly used/misused bottled substitute> If I had to judge by looks, I'd say yes.  <keep your bulbs clean often> Thanks lots! -Becky <best regards, Anthony>

2/3/03 - Lighting and coral selection Hi there, <Howdy. Paul in the hizouse and messing it up after a few too many tacos for lunch......bad breath....I mean.> would 1 36watt PowerCompact and 1 55 watt power compact light be enough light on a 29gal. <In my opinion that is a very low amount of light for most corals. Without getting into the weak "watts per gallon" argument/theory/thing. I would like to see at least 1 more 65watt PC added to that. Anthony Calfo has written a pretty easy to follow and understand methodology for lighting (So have many others). Please refer to the following links as well as do a search here in the google WetWebMedia search tool: http://www.wetwebmedia.com/marine/setup/lighting/index.htm http://www.wetwebmedia.com/marlgtganthony.htm > tank for  toadstool leather <Maybe too little light for most of the Sarcophytons. Please look here: http://www.wetwebmedia.com/alcyoniids.htm>....finger leather <depending on what is truly referred to as a finger leather the previous link also could apply>....mushrooms <I think you could get away with the lighting you currently have with the corals placed about halfway up your rock structure. See here: http://www.wetwebmedia.com/corallim.htm>....candy cane coral <Please see here: http://www.wetwebmedia.com/faviidae.htm>and green brain coral? <Definitely would need a bit more light as this coral should be placed on the substrate with adequate room for expansion. This coral will inflate itself to not only pan for light sustenance but also as a method of feeding on physical foods such as mysids and other small meaty food chunks. Check this area out for more info: http://www.wetwebmedia.com/trachyphlliidae.htm> if not which ones would be ok with that amount of light? <I really hope you can get more light. Why be limited by less light? Get the most out of the hobby instead of limiting/settling for a few corals at that light range. I have seen new fixtures for around 100 bucks or less through mail order or even DIY projects would be a bit cheaper many options here....since your tank is still cycling, maybe save some money for more light before spending on corals. If not I think the mushrooms and maybe a few zoanthids (beautiful animals can be had from LFS and mail order) may be your best bet. In some cases with inadequate lighting it is possible to keep a great many corals through a proper feeding schedule with proper foodstuffs. This is a more advanced technique and don't recommend to most aquarists. It is difficult to pull off and requires dedication and good water chemistry/husbandry practices. More light would be ideal for the corals you speak of with the exception being the mushrooms> and what's the highest the phosphate levels should be?<You would be better of reading our coverage on www.WetWebMedia.com. This is a rather large question that cannot be answered briefly in an email. The simple answer is to control their input into the tank, i.e. use purified water and not overfeed. I usually find that water changes with good quality source water, coupled with good protein skimming and the use of a phosphate-free activated carbon product, will really help control phosphate problems.> thanks allot, <Thank you Eric. Keep the questions coming and have a great day.> Eric Coral Lighting needs Crew, <Hi David, Don today> Would a 48" 4x55W Helios compact fluorescent fixture be enough in a 75 gallon tank for most corals?  Or is more lighting needed? <Well David, 'most corals' is pretty ambiguous. I would say OK for corallimorphs, many polyps, and some soft corals. Most LPS and SPS would be out. What lighting is needed? As written before here, you need to know specifics about what you want to keep. It is difficult (but not impossible) to keep corals that have strong light needs with those that need lower light in the same tank. Use available references to find classes of corals that have the same needs and then progress from there. You will be less frustrated and the corals you choose will be less likely to die from environmental conditions.> Thanks, David

Lighting Hi <Hello DW> You guys are providing a great service to the aquatic community. <Much appreciated> I am confused on some lighting issues.  My tank is 96x24wx26h for 240g with a  center bar.  I will keep only SPS and clams.  They will be placed at  all levels. I have noticed a trend in your recommendations toward  higher wattage for SPS corals.  My choices are 4x400w, 6x250w, or 4x250w MH  in the range of 14K.  I will not use actinics.  The ballasts will be  IceCap. <For clams and SPS corals, I would go with the 6x250.  This will give you a little over six watts per gallon, and that should be great for your clams/SPS's.  James (Salty Dog)> Thank you for the help. <You're welcome> DW

"Modest" Lighting...What's In A Name? Hello, <Hey! Scott F. here today!> First of all, I wanted to tell you that I stopped listening to my LFS advice after going through your site. <Well, there are many fine local fish stores with experienced knowledgeable employees out there! And we're not the experts on everything, but we do have a significant body of experience (learned the hard way!), so hopefully we can be of service to as many fellow hobbyists as possible.> Your site is very informative and very well put together. My question is about lighting. I have been doing a lot of research prior to purchasing my corals and I try to pay close attention to the lighting requirements. More often the lighting requirement I find are moderate lighting requirements. How do you quantify "Moderate"?  What does moderate mean? <Well, I'd characterize "moderate" as being corals that are not as demanding as high-light-loving Acropora or Porites, but not quite low-light-loving. Good examples would be some of the LPS corals.> I have a 46G bowfront tank with 2 96W PC light which comes down to roughly 3 - 4 watts per gallon. Is this moderate? <Well, watts per gallon is not a true measure of intensity, but based on the size of your tank, it sounds like this qualifies as "moderate".> I have a candy cane coral and a green bubble coral.  I would like to get either a Frogspawn or a Torch Coral but not sure.  The LFS told me that I need to get MH lighting for those animals but they are the same LFS that told me that 79 degrees temp is too hot and that I need a chiller.  Plus they sold me a Powder Blue tang and told me that it will be OK in my environment. <Okay...now I understand some of your skepticism. In my opinion, you could keep corals such as Green Star Polyps (Pachyclavularia), Xenia, Anthelia, etc.> Now that I am doing more research, Not quite as gullible.  Is my lighting enough to meet the moderate lighting requirements? <As above.> Also, have you ever heard of clown hosting a torch coral or frogspawn? <I've seen it a few times; not all that uncommon, actually.> Thanks! Louie <My pleasure, Louie! Keep reading, learning and sharing! Regards, Scott F.>

Small Marine Aquariums
Book 1: Invertebrates, Algae
New Print and eBook on Amazon:
by Robert (Bob) Fenner
Small Marine Aquariums
ook 2: Fishes
New Print and eBook on Amazon: by Robert (Bob) Fenner
Small Marine Aquariums Book 3: Systems
New Print and eBook on Amazon:
by Robert (Bob) Fenner
Become a Sponsor Features:
Daily FAQs FW Daily FAQs SW Pix of the Day FW Pix of the Day New On WWM
Helpful Links Hobbyist Forum Calendars Admin Index Cover Images
Featured Sponsors: