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FAQs about Marine Aquarium Heating, Rationale

Related Articles: Heater Impressions (Reviews) by Steven Pro, Marine System HeatingColdwater SystemsControllers

Related FAQs: Heating 1, Heating 2, Heating 3, & FAQs on: Heating Methods/Gear, Heat Controllers (Fans et al.), Measuring/Thermometers, Heating Troubleshooting/Repairs, Makes/Models by Manufacturer, & Chillers, & FAQs on: Fans For Cooling, Chiller Rationale/Use, Selection, DIY, Installation, Maintenance, Troubleshooting, & Water Temperature

Look to the worlds oceans, reefs as an example of thermal stability... they do change, but gradually... Too much change in too short a period of time adds to stress.... disease.

Highest Temperature For Marines.   12/5/12
Hi Crew, Can you please tell me what the highest temperature for marine fish
<?... tropicals I take it... the high/er seventies F. is what I'd shoot for... Higher has its inherent risks, shortening of windows should "something" go wrong... Lower DO for instance>
and which one are more sensitive. I understand inverts should be kept at around 27C Regards, Adam.
<Cheers, Bob Fenner>

Heat Wave…Safe High Temp? – 05/25/12
Hi crew,
<<Hiya Jim>>
Here in the UK we are having a rare heat wave.
<<Ah yes… I lived in East Anglia (Ipswich) for a few years, and remember some May/June temps over 100 degrees F>>
My reef tank is now climbing in temperature. I am getting highs of 84 degrees.
<<This is about as high as you want to let it go/let it remain for any period of time. Do search our site for emergency measure to temporarily bring down the temp, if needed>>
Normal temps are around 79 degrees usually. Tank currently has fish and soft corals plus some LPS stonies such as Euphyllia and Caulastrea. Can you advise, as there's a lot of conflicting info about this temperature range.
<<A high of 84 degrees F is okay in my experience. It is at the high end for sure, and anything more can be cause for concern. But if this is your high temp I think you have little to worry about for the short term…as long as it is stable and the tank isn’t experiencing large daily temperature swings (more than a few degrees over a 24-hr period)>>
I am loathe to spend 400 pounds on a chiller for one season a year.
<<Indeed… But do keep a close eye on things and be ready to take emergency measures to lower the water temperature if necessary. If memory serves, those “heat waves” can linger for weeks>>
<<Cheers mate… EricR>>

Temperature Variation, Austr./Fiji biotope  1/25/09 Hi Crew. I have read through your temperature FAQ, but wanted to ask a question of a slightly different focus. <Sure> I am endeavoring to built a tank of Coral Sea / Fiji species (except for my Duncans, which I love). I was wondering whether the wide seasonal temperature illustrated below (admittedly probably surface temperatures for divers) suggest any value for seasonal variation in temperatures. <I see this data, have been diving in both locales...> Besides the fish and coral, is there any suggestion that any of the organisms benefit from seasonal variation? <Mmm, good question... I don't know> Bacteria, pods, phyto, etc? Aside from high swings "finishing off" already stressed inhabitants, is there any suggestion that variation in RedOx, growth velocity etc actually increase strength? Many plants that thrive in colder temperatures need seasonal variation. <Again... you posit an interesting/intriguing situation...> I had set my controller to vary from the winter maxima and summer minima indicated below. Your thoughts appreciated. http://www.naia.com.fj/research/watertemp_lrg.gif <A great live-aboard for diving... Mmm, perhaps a visit to a large college library... a computer search bibliographic search... Bob Fenner>

Re: Temperature Variation   1/25/09 Thanks Bob. I will keep searching. And actually I meant Koro Sea, but since I have Duncans I guess both are true...Koro+Coral. <Ahh, had thought you meant your Duncanopsammias hailed from Australia's Coral Sea> All the best, John / Fishnu <Thank you John. BobF>

Tank Temperature 6/29/08 Hello! <Hello!> Since I started in the aquarium hobby, I always thought that the ideal temp was between 75f and 80f but recently, reading Ronald Shimek's "Marine invertebrates", he says quote "I consider the temperature range of 81 to 84f as the optimal and normal temperature to maintain all reef animals" also in About.com they think the same way, can anyone clarify this? <Well, either temperature range can work. The key is to avoid swings. If 75 and 84 can work, it won't if your tank is 75 in the morning and 84 in the afternoon! The lower temperature range is more natural for most of the corals and fish we keep in the hobby. The lower temperature affords more oxygen carrying capacity in the water and a slightly longer lifespan for most. The push toward the lower to mid 80's is twofold in my opinion. First, many people battle to keep their tank below 80, while it can be stable at a slightly higher temperature, 83 for example. The other common argument for the higher temperature range is faster metabolism; things should theoretically grow faster. > Thanks Gerardo <Welcome, I hope this helps clarify, Scott V.> <<A comment... this "position" re temp. of marine systems is a bit contentious... the basic pros/cons have been gone over and over... even on WWM. My opinion/direction is to encourage folks to keep their systems a bit cooler by and large... the mid to upper 70's F.... granting them some margin for safety should there be an issue with rising thermal influence... along with slowing metabolic rate and all this implies... longer lives, less maintenance... There are few habitats in the world's seas where natural temperature is in the eighties F. continuously. RMF>>

Re: Tank Temperature 6/29/08 Thanks for your answers! I guess I'll maintain my tank at 78-79f. Gerardo <Welcome, sounds good. I too do maintain at 77-78 deg. F for all the reasons mentioned. Scott V.>

Is Stability The Key?? Temp. control, SW    8/8/07 Ok, so like everyone I want to say thank you and tell you what a great job you do! Now, on to my question. What I can't seem to find is this. If I keep my reef tank so stable that my temp swings are no more than + or - .3 degrees am I ruining my corals (and other inhabitants) ability to handle any sort of major swing in temp? <Interesting to speculate... don't know> Is it better to have a swing of at least 1 degree? <Mmm, don't think/consider that this makes much difference> Is my tank more prone to disaster if it does swing after being so stable for so long? Should I be less worried about stability and more worried about my corals ability to deal with a slight swing in temp? Am I over doing stability? <Don't think so... Though there are definitely areas of the seas/reefs that do undergo at times rapid and extreme changes in chemistry, physics, a good deal of places have very slight, slow changes only> .....lol I guess what I am asking is this....Should a tank be kept so stable that it runs the risk of possibly depleting the natural ability of it's inhabitants to deal with temperature swings? <Again, I think this is likely a minor matter> Is it better to let the tank have a swing of a degree or maybe even 2 over a 24 hour period to keep things "on their toes" so to speak? I'm really curious as to what you folks think! Regards, John <I sense a doctoral thesis or three here... Bob Fenner>

Stable water temperature? SW speculations on a return from HI snorkeling... Aloha Mr. Fenner! <Howdy!> I just got back from the Big Island and Kauai, where I spent ten days snorkeling to my heart's content. <Bet you have a nice tan!> I want to ask you a question that's been on my mind for some time. I have read, over and over again, on this site and in your book how important it is to keep the water in one's aquarium at a stable temperature, and that stability is more important than achieving a specific temp. <Mmm, yes> The reason given is that the enormous ocean environment provides a stable temperature, which our livestock is inherently accustomed to. <Agreed> So, on to my question: I have noticed in years past, and again on my recent trip, that when I snorkel, I encounter patches of colder water, and then patches of warmer water, in the same general area, while I'm observing species that I have in my tank at home. What do you think? <You are certainly correct... Particularly on the Big Island, there are zones where much cooler freshwater is intruding from "Pukas" and cracks in the rock... having traveled from higher elevations... this presents a difference in osmotic pressure and density as well as a varying thermal regime... Yet the life there appears healthy to me> Are these temp differences I notice more subtle than I realize? <I believe so... Maybe one way of putting this situation in perspective is to realize that the motile animals (do note the difference in species make-up and abundance in these areas in the way of not-so motile and attached biota) do move in/out of such zones (near the land, surface)... and that they are in good shape to begin with... and I'd speculate that the mixing in these areas is to their advantage in avoiding predation...> I have been very curious about this, as I do struggle to keep a stable temp in my tank in my south Florida home, especially in winter months. By the way, I was struck by the incredibly strong currents in the ocean! <Heeeee! More than Tunze and Hydor powerheads?!> I have four power heads in my 130 gallon, and I fear they are woefully inadequate! <Ah, yes... a useful lesson> I appreciate whatever comments you have to make, and continue to enjoy and learn from this site, so thanks! Elise <Thank you for sharing... I do think "constancy" is an important aspect of our successfully maintaining a small part of a captive sea... but it is only one area of concern/influence. Cheers and a hu'i hou! Bob Fenner>

Heating/ cooling and too much too soon? 4/19/07 <Greetings, Hays.> I have a 26 gallon bow front tank. It has been set up for about 3 months. <"Set up" as in cycled, or filled with water? I hope you mean cycled.> I have lost several fish lately and currently have only a prawn goby, Sixline wrasse, cleaner shrimp and emerald crab. <For starters, several fish more than this would be too many. Test figures are very helpful here, and if you don't own a kit, you need one.> Coral include, polyp Zoa«, pulsating xenia, feathery leather toadstool, flowerpot coral, double ricord. mushroom and tube worm. <Is this a first attempt at reef-keeping? I am surprised at the species of coral you have together here for such a young system. Goniopora is a species regarded by the majority to be an "advanced" reef-keeper species.> My lights are 130-watt power compact, <Just one?> heater is a 100w Rena Cal (best one I could find locally) with temps staying between 76-80. <Too much fluctuation, here.> I live in Mississippi with ridiculously hot summer days approaching. I am wondering if I need to get a chiller and/or remove my heater?   <Removing the heater may seem well and good at first, but for stability, you should have both and set them so that neither is working against the other.> Is it a good idea to use both in order to keep the temp in a certain range? <Oh, yes. See above.> I turn my air conditioner off during the day to save on electricity, but it is cool at night. <Temperature swings of two or more degrees in a day are also stressful to fish and inverts. Imagine the volume of the ocean and the relative temperature stability of that huge mass of water.> I am also curious of how many hours you recommend the lights be on. <See below.> I have had a problem with brown algae on the glass, is that more from the fish dying or too much light? <Hmm. Interesting point. Many algae problems are attributed to chemical instability or imbalance in the system, and this condition is very stressful to animals. Usually the brown film you mention is considered by most to by a mild irritant, but only visually. Most of the time it is part of general maintenance of the system, and can even phase out as other more desirable forms of competition spring up. As for the lights, I would think that everything in this system *should* be fine with the light levels you currently use (Goniopora is often found/collected in less than clear waters, in medium light. I would recommend 8-11 hours of operation, depending on factors such as heat-contribution, power consumption, and even algae control (But the last the least). Ease into this if it is different from your regular schedule.> Thanks for the help. Hays <Welcome, and good luck! -GrahamT>

Reef Tank Water Temperatures/Fluctuations - 12/14/06 Hi, <<Hello>> I have a 75 gallon reef tank with some fish and other creatures in it.  I'm having some temperature adjustment issues now that it's winter.  My sump [55 gallon] with the heater is in the basement, so it's colder there.  I try to keep the sump temp at about 77, so it doesn't get too hot in the tank during the day.  My range generally goes from about 76, 77 at night [75 really cold nights]  to 78, 79 during the day in the tank - it's hard to tell because I have both digital and paste on thermometers and sometimes they read slightly differently, even from one side of the tank to the other. <<Mmm...the temp swing (3-degrees) is not that bad, but you should ditch the paste-ons and obtain/use a single reliable digital thermometer for reasons of consistency>> I'm trying to keep both the fish & the corals happy.  I'd appreciate it if you could let me know what the acceptable ranges are, as I've read different opinions. <<Water temperatures between 77-84 degrees are acceptable...in "my" opinion [grin].  The key is to keep the night/day fluctuations to a minimum, though a "swing" of three degrees has not proven deleterious in my experience.  I suggest you add a second heater to your sump in the basement to help with maintaining temperature at night>> Thank you! Linda in upstate New York <<Quite welcome.  EricR in sunny South Carolina>>

Heating/Cooling a Tank Bob, <Anthony Calfo in your service> After reading through many articles at WWM I found that water temperature fluctuations may be one of the main impacts to fish's health.  <yes...very significant! Welcome to Ich-ville for starters> There are some days in the summer where the outside temperature swings way up and way down and my condo is poorly insulated so these changes affect the inside temperature dramatically... even with the central air on all the time. This has lead to many parasite outbreaks and loss of livestock... and yes I do have a 25watt UV sterilizer.  <do read my past posts about how to correctly keep up with a UV for efficacy (weekly carbon, monthly cleaning, 6 month bulb life, prefiltered water only)> I am thinking about getting a 1/4 hp Chiller for around $750.00 for my 180 gal. FOWLR system. I am trying to stabilize the water temperature as much as possible. I was told by some aquarists that fish get stressed if the temp. fluctuates 2-3 in degrees at any given time within the day. Is this true especially on a tank of this size?  <true of any tank size... 4 or more degrees and I would be surprised if they didn't get Ich within a month> Is it really necessary for me to invest in the chiller device?  <if your max high temp is not so severe (under 83F) then simply set your heater for a naturally higher temp (add second heater for stability) and compensate by less fish, less feeding and better aeration (protein skimming, ozone and the like)> Some feel that a chiller is not so effective... unless you are spending well over 1,000 on the best models.  <not true... a properly sized and installed chiller will do its job regardless of the price. A chiller throws heat... do not mount it in the cabinet under the tank where the heat will build up. Near the ceiling or in the next room (downstairs, behind the wall, whatever... to dissipate the condenser heat will go a long way toward energy savings and efficacy)> Are there any affordable solutions for maintaining a stable temperature in my fish tank? <do make the very best use of cooling fans for lights when on and reduce the number of internal powerheads by replacement with a single large external water pump on sump... sources of heat. Best regards, Anthony>

Reef tank Hots, or Not so Hot Hi Bob <Gary> I have a short question with regards to the best temperature to keep a Reef tank at.  So many people say different things.  I have both Corals and Fish in my tank and I all seems to be fine, but I would like to know if my temperature that I have my tank at is correct.  I currently have the water at 75.2F.  Some people say that this is to low.  What would you say. Hope to hear from you soon. Kind regards Gary <This is actually quite a "challenging" question. You and I have heard much higher temperatures recommended for general reef set-ups... some folks advocate mid eighties F and there are proponents of even warmer water! I am much more akin to suggest moderation here... and can present the principal advantages to both ends of the spectrum. At higher temps. most all life (fishes, invertebrates, algae, vascular plants...) that folks keep does grow faster (not always better however), looks more "vibrant" is more active... at lower temperatures the opposite of the previous is so... but "things" that go "wrong" do so much more slowly at reduced metabolic rates, livestock lives longer, tanks are easier to maintain... Sorry for going on and on... the short answer is I would/do keep my tanks in the mid to upper 70's F. Bob Fenner>

Temp concern 7/26/05 What is considered a big swing, ( sorry for the dumb question ) temp at current is 77.8 degrees.  A time factor is involved here, Heather.  A five degree swing in eight hours isn't good.  In my opinion, no more than a 5% swing in 24 hours.  Keep in mind, the water temp where our fish come from is relatively stable, there are no swings.  James (Salty Dog)> thanks for the quick response and help :)

Stability Is The Key... Hey guys, I had two quick questions.  First, what temperature should I keep my tank, which houses a Humu and a damsel. <I like a temperature of 76- 80 degrees Fahrenheit...Stable temperature is more important than any one specific number, IMO> My other question is that I have some sort of reddish dots/algae on the glass that I am not able to scrape off successfully, do you have any clue to what it is?  I do 25% water changes weekly.  Thanks a lot, Jon <Well, Jon- it sounds like some sort of algae or diatom...Hard to be specific without seeing it. However, it's a safe bet that, if you continue to exercise good husbandry (such as the water changes, with high quality water), and utilize various nutrient export processes, than this possible nuisance algae will go away. Good luck! Regards, Scott F>

Tank Temperature 10/8/03 I have had all kinds of advice on tank temp. Anywhere from 72 f to 78 f. What temp do you prefer? And what temp would you recommend for a 40 gallon reef tank with 3 fish and lots of coral? My current temp is steady @ 75 f. Thanks, Jason <the water temp depends on what you will be keeping. Freshwater or Saltwater, and fishes from what region? In general though... 76-78 F is a good range for most tropical species. Anthony>

- Specific Gravity & Temperature - Hi, Hope all is doing well there.  I have a 75 gallon F/O tank.  My fish are:  2 percula clowns, 2 lemon butterflies and 1 coral beauty angel. Please tell me what you recommend for tank temperature and specific gravity.  I have been keeping the tank at 76 degrees and the specific gravity at 1.021.  Thank you, James <James, I'd shoot for 1.025 for salinity - it's what the ocean is typically at. As for temperature, you could go a little higher, but there's nothing wrong with 76F - 76-78F is ideal. Cheers, J -- >

- Dealing with Heat - Howz it goin??   <It's goin'...> I have what could be a problem... I am living in Ottawa Canada, and our summers are VERY hot.  It was 34 degrees today, and my fish tank's temperature is currently at least 31.  First of all, will this be a problem. <Yes... it will raise the metabolism of anything you are keeping in the tank - most certainly will be fatal for corals. Fish can tolerate it for a while, but not for too long.> If so is there anything I can do to fix it. <I'd start by running a fan across the surface of the water... then, perhaps lighting the tank opposite daylight, to avoid heat build up... there are other options, but I would start here.> Thanks for the help. Steve <Cheers, J -- >

Questions on temperatures - 11/17/04 Hi guys. First like to thank you for the great site, I have been finding so much info here. <Excellent. Tis our modus operandi!> But I do have a question. I have had my saltwater tank going for 87 days now. <2 and a half months is still quite a new tank in my opinion.> 45 Gallon tank, 44 lbs. Live Rock, (2) AquaClear 200, (2) Powerhead 402, Red Sea Prizm Protein Skimmer, 30lbs. Seeded Aragonite powdered sand, 40lbs. Crushed Coral Substrate. <The sand is underneath the crushed coral? Not necessary to do this> (2) 30W Aqua Glo "12 hours/day" (2) 10000K Blues "14 hours/day" Livestock: (1) Bianni Cardinal, <Banggai??> (2) Pajama Cardinals, (1) Scopas Tang, (2) Clownfish "Percula", (1) Dwarf Lionfish, (1) Coris Wrasse <Too many fish for this small a set-up The cardinals are a good choice, the clownfish is likely fine, the Scopas, the Lionfish, and the Coris concern me. This a quite mis-understood fish. The usually range in size but if I were you, I would positively identify my fish and do some research on their size and habitat. I think you will be shocked.> (4) Electric Blue Hermits, (1) Scarlet Red Hermit, (1) Electric Orange Hermit, (2) Mithrax Crabs (1) Pineapple Brain Coral, (1) Xenia Pulsing Coral Temp: 25, <77 Fahrenheit> pH: 8.3,  Ammonia 0.0.,  Nitrite 0.0,  Nitrate 0.0 ,Phosphate 0.1,  Gravity 1.025,  kH: 13 dKH,  Cu 0.0,  Ca 440 I do regular maintenance every week, having got my brown algae under control. <Excellent to hear!!! This the proper way to start out. Good on ya, mate!> My question is this.  I have read that many reef keepers are keeping their tanks between 80-85 degrees.  What are the pros and cons of keeping my tank this warm? <Well, I would rather state, in my opinion, having traveled to quite a few tropical locales and have been diving in various tropical regions, I would be more concerned with the average of low and high water temps as it relates to reef keeping. Do some research after positively identifying you inhabitants, look at their region, there should be some info on the average temps of their location. Then adjust your tank. I personally prefer the average of 77-80. My tanks do tend to fluctuate in temp as lights tend to warm the water a bit. Plus summer temps tend to also help my water to warm. So you may need do some adjusting or add a chiller or something of that magnitude.>  Do corals prefer a warmer tank? <74-84 is, in my opinion considered extreme ends of the spectrum when it comes to most corals> And do you think my lighting schedule is ok? <Should be OK. Watch the corals. For pulsing Xenia it is likely enough light but I think the Pineapple coral will likely need more powerful PAR lighting. I keep my schedule at around 10 hours or so. It really is determined by the animals, then by lighting, then schedule in that order, in my personal opinion. Thanks for participating! ~Paul> Water temperature for my FOWLR angelfish tank Good Afternoon, I have a 125 gal FOWLR tank. 1 5 inch Imperator & 1 7 inch Blue Faced Angel. I just added a 36 watt UV on the tank with a pump for it in my wet/dry. The temperature of my water is 83 degrees. Do I need a chiller? I was told that Angels like warmer water, but will that do harm long term???  <Should be fine... will slightly shorten life spans, could cause trouble in terms of gas solubility... in the event of power outage, overfeeding, die-off... Bob Fenner>

Tank Overheating - 06/13/05 Hi! <<Hello!>> It is miserably hot at the moment in Montreal (no joke, it can be hot in Canada too).  My tank's temperature is peaking at 30C since a week. <<Okay, for my/our readers use that converts to 86F.  This temperature is higher than I would recommend someone to keep their tank, but not really "out of bounds" if kept consistent.>> I just bought 130lbs of Fiji LR a month ago.  For now that's all there is in the tank with a baby ocellaris and a wormfish (magnifica).  I am already running a fan over the tank and within a week I am getting air conditioning (ouf!). <<Wonderful stuff that air conditioning...of course I live in the sultry Southeast.>> Is the LR/micro fauna endangered by such temperatures (30C)?  I am freaking to think the LR may be "damaged" (it was a big investment) and also worried about the friendly fishes.  Should I really be worried? <<If you're "peaking" at 30C and dropping no more than a couple degrees at night I think you'll be fine for now.  The elevated temperature will get everyone's metabolisms running, but if you ensure good water flow and oxygenation your rock and critters should make it without any permanent damage.  And keep in mind your rock was collected from very shallow waters that get "very warm" under the hot tropical sun...even totally exposed at times during low tide...little concern here, really.  But if you want to go to the trouble, fill a couple 2L soda bottles about half full of water and freeze 'em.  Then during the hottest part of the day float the frozen bottles in the tank to help keep the temperature down.  If that's not practical for you then add another fan to blow across the surface of the water.  You can also set the timer on your lights to shut off during the hottest part of the day; it won't hurt to do this until you get your conditioned air.  At any rate, I think all will be fine until the air conditioning kicks in.>> Thanks! Dominique <<Welcome, Eric R. (currently sweltering in 90+ temps and humidity himself)>> Temperature Swings and Algae Things (New Tank Breaking In> Hiya Bob or whoever is sitting in today, <Howzit? Scott F. here today!> My tank has been circulating and in operation for about 5 months, the lights were only switched on for the first time about 4 weeks ago, only a number of Chromis in the tank when they got switched on. The tank is 9'x2'x2', about 320g including sump and refugium (which isn't populated yet), with what can only be described as an abundance of lights, 4x400w MH and 4x60w actinics. <Sounds great!> Originally I was going for an SPS setup but my tastes have changed and primarily I will be going for stonies, mushrooms and Zoanthids. <I am a big fan of some of the LPS corals, myself, such as Faviids. Maybe not as "trendy" as the SPS corals, but every bit as pretty and interesting, IMO!> So my lighting needs have definitely reduced, although I would like to keep clams. <An interesting mix.> The problem I had is soon after switching on the lights, I had to go away for 2.5 weeks with work. My girlfriend kept an eye on the tank, and I had a man from the LFS who helped set it up come round once a week. <Good!> When I returned, I had a serious algae problem. The front of the glass had been cleaned by the LFS guy, but there were filamentous algae growth in nice bunches over various parts of the tank, and the back screen had almost a total cover of it that looked like it could be peeled away. <Unfortunately, this is a very common occurrence in new systems, which are rich in nutrients and short on mature nutrient export systems.> I went to the LFS and bought a load of snails and hermit crabs (I did have a small number of both of these already), and also got myself the first of my real fish, 4x Yellow Tangs. These were preplanned and not an impulse buy and it seemed like a good time to get the algae eaters in. <It is. However, I'd like to think that you'll embrace a quarantine procedure in the future with all new fish, particularly Tangs, which are notoriously susceptible to parasitic infections.> Upon return I discovered my second problem, the temperature  outside was about as hot as it gets in England, about 31C, and my tank temperature was up to 29C. This I found out as I was letting my Yellow Tangs acclimate in their bags. (As the tank was empty bar the Chromis and cleanup crew I didn't quarantine) <Still a good idea, as you don't want new fish to bring potentially infectious diseases into this new tank...> Immediately turned off the lights and went outside to check if the chiller was working, it was, but I guess the poor thing was struggling with it being so hot outside. <Understandable!> Next day, the Tangs seemed to be fine, the cleanup crew were getting around and nothing seemed the worse for wear. <Good to hear.> I changed the lighting period to switch on later than usual, bringing the lighting period to start as the sun is setting, and hence colder outside to give the chiller a better chance. This didn't seem to make much of a difference, as for the last hour or so of the 12 hour main lights lighting period my temperature had once again hit 29C. Fortunately, there is little in the tank to get stressed over this, and the Tangs are coping far better than I thought they would. I have read from Eric Borneman's book that temperatures on the reefs can exceed this. <Yes, but it's not a good idea for extended periods of time, of course.> But I bet the swings were not so high overnight. <Correct, in most cases, although some lagoons and reef flats affected by tidal changes do have such fluctuations.> I have read on your site that swings of over 4F are to be avoided. <Ideally, yes.> Is this definitely a big problem that I need to sort out or can I allow the tank to take a nearly 5F swing almost everyday? <Well, it's not an ideal situation on a daily basis, so you will most likely want to make some hardware changes to cope with this fluctuation in temperature.> I assume not and see 3 potential solutions to the heating issue: 1> Change the lights, as stated, it is a lot of lights for the system and probably should be reduced. <Certainly will save on energy costs, but you have to make sure that your future plans for this system will not require such high intensity lighting, or you'll be in for frustration!> 2> Add a second chiller outside inline with the first to maybe kick in at about 0.5C higher than the first. <A functional idea, but it may be better to simply invest in a more powerful chiller and just have one.> 3> Redrill the lighting fitting to have the lights sit another few inches above their current location. <Again, another potentially viable idea.> Any thoughts on which I should use or definitely shouldn't use? <Personally, I like the idea of cutting back on the lighting (if that works for you), and perhaps a more powerful chiller. Additionally, you may want to blow a fan or two directly into the sump, for evaporative cooling to occur.> Also my algae problem is real bad, I am going to trim back as much of it as I can for now, and I have no idea where the nutrients for its growth have come from. <Lots of possibilities: Source water, material in the rocks and substrate, even salt mix or carbon! Do investigate.> Once it is pretty close to the rocks I am going to see how well my Tangs can handle the situation. <Hopefully, they can make a measurable impact.> Any ideas on algae control or do you think I should be ok with what my current course of action is? <I would look into the possibilities outlined above. As stated previously, such algae outbreaks are common in new systems, so don't be discouraged. Continue to manage nutrient export processes (i.e.; aggressive protein skimming, water changes with good-quality source water (RO/DI), careful feeding, general good husbandry habits, and a healthy dose of patience! You can and will get through this phase if you think along those lines.> Sorry for the lengthy email but I wanted to set the scene a little first. <No apology needed; you did a great job!> Thanks in advance, Gary <Best of luck to you, Gary! Hang in there! Regards, Scott F.>


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