View Full Version : Refugium lighting: 24/7 or RDP

07/04/2000, 12:28 AM
I have read that running the refugium lights 24/7 is supposed to keep the macro algae from dieing. My question is, is it better to run them 24/7 or would a reverse daylight period be better? A rdp is supposed to keep the ph from dropping at night. Will running the lights 24/7 have the same effect? Any advantage of 27/7 over rdp?
I'm planning a 20 gal refugium with a 4" sand bed. It will also hold whatever macro algae I can find.It will be lit by 1 65 watt pc bulb fixture from LOA. Bob

Visit my new web page: http://bobsreefermadness.homestead.com/index.html

07/04/2000, 06:33 AM
I ran mine as 24/7. I found the most outa wack spectrum bulb to grow as much algae as I could down there. It worked very well, after 3-4 weeks, tons of algae and no traces of phosphates. Once the Phosphates were burned I cleaned all the algae out and place some calurpa in there where it slowly grew and stated to remove my nitrates. I like the idea because it also will over time the algae in the main tank will actually disapear. As far as keeping pH up, I never saw anthing come out of that on my tank. It still seemed to dip.


- Eric

My Homepage (http://lindquistfamily.net/eric/)

07/04/2000, 06:46 AM
I run my 24/7 as well, just on flourescents (2). It should have the same effect at night because I think the whole idea is that if the algae is photosynthesizing during the night it will help keep the pH stable. I have little to no macro in my main tank, and Im amazed how much life is down there. So far I have found my method well worth it. Also one less timer :).

07/04/2000, 12:20 PM
I use RDP and my pH does not dip below 8.10
I have Halimeda in my 100 gal reef and my 5 gal refugia. If the Halimeda dies off, it becomes part of the substrate. Much of the sand in Australia is from Halimeda which get ground up and eventually becomes sand. The Halimeda grows like weeds in my main tank and refugia. I also have a calcium reactor and Halimeda is a calcarious algae so it will absorb calcium.

07/05/2000, 12:00 AM
24/7 here too. But I experimented with reverse day cycle too, my caulerpa never went sexual.
I have a 10 gal refugium for a 75 gal main tank, upgrading it to 20 or 30 gal soon, it all started with a 6 gal caulerpa tank :)


My webpage (http://www.wyx.com/iheo/tank/aquarium.htm) Updated 3rd July 2000

07/05/2000, 12:05 AM
sorry, double posted...

[This message has been edited by Joaco (edited 07-05-2000).]

07/05/2000, 03:50 AM
Well so far it's 3 to 1 in favor of a 24/7 light period. This keeps the macro's going and the ph up.Thanks for the feed back.Bob

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07/05/2000, 10:44 AM
I run mine 24/7 just for the simple fact that you will get twice as much algal growth than with reverse daylight=twice as much nutrient export. IMO, the benefits of added water filtration far outweight the pH stabilization issue. I never really noticed a pH difference in my tanks (limited of course by meager test kits). your choice of lights will work just fine. If you can stand the long wait, throw in a few mangroves from floridaplants. They really make an attractive display and help keeping nitrates in check.


"Bake 'em away, toys."

--Police Chief Wigham

07/05/2000, 10:54 AM
Well make it 4 to 2. Joaco and I had this discussion before, here is my take:

Plants use light to generate food hotosynthesis). This food is built up within the plants cells and is eventually used for growth and reproduction. Plants need darkness to grow (I'll skip the details).

Need proof? Look at a plant sitting on a window sill. The plant will always "grow" toward the window. In actuality, the "dark" side of the plant is growing, while the "light" side is too busy making food.

Therefore, 24/7 lighting will stunt the growth of the macro algaes. The use of CO2 in the photosynthesis process (breaking the C atoms from O atoms) is a "light" phase process. During the dark phase, the plant uses its stored food source and the process is reversed. Animals do something similiar, but since we can't "make" our own food, we consume and rely on our plant friends for an O2 source.

The theory behind reverse daylight scrubbers is that you will have an O2 source (and use of excess nutrients) during hours when the main tank is a net O2 user (and vice versa).

But as Horge has pointed out before, it could depend on how much "photos we have on the table".

07/05/2000, 01:32 PM
That was way back in March, I believe, over at TheReefTank.com! To reprise my hamhanded summary of photosynthesis back then (with due apologies to Doug1 and Steven of TRT):

In the day both light and H20 are taken in and via photolysis made to yield O2, ATP and TPNH2. Calvin's Dark Reactions take the latter two and, in combo with CO2 nabbed from the atmosphere, churn out packets of starch. (You can look up how PGAL-to-ADP piles onto starch yourselves, heh-heh). It is generally at night that these starch packets are broken down into sugars and disseminated throughout the plant for use in tissue building.

A very simplistic way to reason out why energy stockpiling and tissue construction seem to have been segregated is for efficiency: unable to do anything about the sunrise and sunset, plants have evolved to focus more on starch-making while the sun shines, while at night they can focus more on growing.

Lighting a seaweed patch 24/7 doesn't 'necessarily' stop a plant from growing. But it can be wasteful excess both for the plant and for the person footing the light bill. If the growth rate pleases you, and any leaked sugars/starches don't bother you, hey ---it's your turf. Or macro.

Which brings me to my final burp:
We seem to be discussing an algal filter.
(If you are utilizing turf algae, then you can call it an Algal Turf Scrubber --just don't try to sell it as such, or you will step on the patent rights of the wonderful Dr. Walter Adey) It exports dissolved nutrients via harvest of the algae utilized.

A refugium is a whole other barrel of pigs' knuckles. It serves as a predator-free breeding ground for certain critters that would have trouble flourishing in the display tank. Some of those refugium critters' planktonic offspring can serve as very healthy snacks for our display-tank inhabitants (hence the term).

If you wish to combine refugia and algal filters, call it a combination, but let's try not to confuse some beginners that may be tuning in. The two are distinct as concepts. :D

[This message has been edited by horge (edited 07-05-2000).]

07/05/2000, 02:15 PM
Horge has a point. For my refugium, I did mention the sand bed but I didn't really talk about any pods. I could see how someone might think a refugium is just another term for an algae filter from reading my post. I was focusing on the lighting aspect. Thanks for the clarification and the explainations.Bob

Visit my new web page: http://bobsreefermadness.homestead.com/index.html

07/05/2000, 03:02 PM
I don't know if this is completely on-topic, but in my ATS, I run RDP. My thinking is exactly the same as some of the others who posted regarding the dark reactions of the Calvin cycle. In my experience, I have had less success growing algae by lighting it 24/7 than having it on a regular light/dark schedule. Either way, I don't think it really makes a profound difference, but I could be wrong. If half the people do it one way, and half do it the other, and both sides are having success, does it really make that big a difference?

07/05/2000, 05:17 PM
Thanks for the extra info guys.
Actually mine is not a refugium, but a tank growing caulerpa macroalgae only. I call it simply algae tank:

the main reason for mine is nutrient export.
This tank is going reef in the next weeks (I'm getting a bigger FO), the 75 gal reef will have a real refugium under it, including deep sand bed, not just the macroalgae :)

BTW, my caulerpa never went sexual, some people say it's because the 24/7 photoperiod, but I experimented a lot with light exposure times, even so my caulerpa never went sexual.

If the 24/7 period would prevent the macroalgae from going sexual, why don't we experience that in RWD photoperiods? As far as I remember, Baensch doesn't mention it in Marine Atlas vol 1, caulerpa chapter.

I have been told Mike Paletta said this about 24/7 preventing this situation. Was it when he researched the effect of EcoSystem and 'miracle mud', by Leng Sy?

Any input about lights / sexual reproduction of caulerpa macroalgae?



My webpage (http://www.wyx.com/iheo/tank/aquarium.htm) Updated 3rd July 2000

07/05/2000, 05:35 PM
You are correct about Mike Paletta's statement about the 24/7 lighting. Here's a link: http://www.ecosystemaquarium.com/seascope14.html
Nice tank you got there! Bob

Visit my new web page: http://bobsreefermadness.homestead.com/index.html

07/05/2000, 07:23 PM
so to keep the combo working on the edge of performance we are more or less trying to find the right photo period for the particular speciemens we are growing ?? i have been running 20on and 4hrs off flowing with miday works for me
wishtobeafish :)

07/07/2000, 12:09 AM
Thanks Rob! I saw your tank featured at www.reefland.com (http://www.reefland.com) , nice reef!

About the 24/7 photoperiod, here is Mike Paletta's quote from that link:

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>It is interesting that the water is crystal clear and does not become yellow over time as in other reef systems containing even a small amount of algae. This maybe a result of the 24 hour light. Lack of darkness may prevent the production of a yellowing compound called gelvin, thought to be a product of the nighttime breakdown of algae chloroplasts that are released into the water.<HR></BLOCKQUOTE>

it really doesn't explain it, just says it *maybe* a result of the 24/7 photoperiod (lack of darkness).

I would love to see Dr. Ron Shimek's thought about the subject since I hear over and over that 24/7 photoperiods prevent caulerpa from going sexual, but I never found any info to back it up.


My webpage (http://www.wyx.com/iheo/tank/aquarium.htm) Updated 3rd July 2000

07/19/2000, 07:54 AM

While I agree that higher order plants need a dark/rest period, this does not seem to be the case with macro/micro algae. I have been experimenting with algae filters since the 1980’s including reverse daylight. I have read hydroponics studies where the growth rates of higher order plants were measured to be almost double when plants were given a 6 hour rest period.

I am using an EcoSystem filter system where the macro algae is illuminated 24/7.

The 24-hour approach has the following advantages:

1 The macro algae does seem less prone to sexual crashes.

2 The system pH is even more stable than reverse day/night systems. Even thought my alkalinity is not particularly high, my day night pH varies only 0.05 pH units.

3 The oxygen level remains high 24 hours a day due to the fact that the macro algae is photosynthesizing 24 hours a day.

4 The macro algae does seem to grow more and produce more oxygen bubbles when the main tank is dark. I believe that this is due to the higher production of CO2 by the main tank during this time.

My system has only been running for a little over a month, but the macro algae has doubled in size and has almost completely filled the refugium. This is a faster growth rate than I ever observed with reverse daylight systems.




07/19/2000, 05:04 PM
This post has really helped me out a lot! I was confusing a refugium with an algae tank. Now, if I have it right, the refugium keeps animals and some plants, and is meant to supply at least a portion of the food for a reef tank. The algae tank removes the nitrates and phosphates and silicates from the water. Is this correct?

Joaco, you mention that you will be placing a real refugium "under" your tank. If that is the case, you will need to pump it back up to the tank. Will the pump destroy a bunch of the live food going to the tank?

Larry M
07/19/2000, 05:17 PM
TBH, I don't see the hang-up on what you call it. What do you want it to do for you? A refugium can be a macro-filter, and vice-versa, IMO. I have had refugiums as small as 2.5 gallons. Copepods and other critters love to live in macro-algae, IME. So big or large, I say grow some macro-algae in there, prune it occasionally to export nutrients (you will have to anyway) and don't expect it to stabilize ph unless it is pretty good sized. But it's all good. :)
As for lighting 24/7, it might be a good idea, but it's not natural. I have never had a problem with calerpa going sexual on a reverse photoperiod, fwiw.

Larry M

Visit Reef Stores.com ( The liaison between hobbyists and on-line retailers.

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07/19/2000, 07:10 PM
Hey Horge,

It has been a long time since my basic biology (to much organic and biochemistry has gotten in the way), so I have probably forgotten something. But, I don't recall a molecule TPNH2 involved in the so called light dependant reactions.

Is it another name for NADP/H ?

In any case, all of the basic biology of Calvin-Benson cycle got thrown out the door when we hit upper level biochem / organic – it’s all about the electrons really.

The so called ‘chemical reaction’, of ATP to ADP and back get really interesting once you start following the electrons. All those damn intermediate molecules that you have to go through just to get an electron to go ‘up hill’ ...

Oh no, the flashbacks are coming, no stop, please make it stop ahhhhhh

nucleophylic substitutions,
Sn1, Sn2
E1 E2 reactions
chirality (shiver)
Bacterial Rhodopsin phase change

please make it stop,

heme group of hemoglobin and iron-oxygen affinity
nucleotide drift
genetic evolution
beta pleated, alpha pleated ... ahhh

You make me want to bust out trusty old Voet and Voet and go run some Michaelis-Menten kenitc studies, on ... hmm, what would be a good enzyme. Oh I know how’s about one of the ATPases, seems fitting to the topic.

Horge, I’ll get you one day for causing these flashbacks !!! You brought back the demons ;)


07/19/2000, 09:26 PM
I didn't get a word from what you said last :o
Do you think caulerpa will prevent from going sexual with 24/7 photoperiod? yes, no, why?

The only thing I got was 'genetic evolution' :D :D

yes, I will be using a pump for the refugium under the main tank, I'm working on a interesting design with some friends, no blades will hit the pods at all.
And as Snailman told me from one of Rob Toonen's posts, the problem wouldn't be suction itself since water has a slime-like property (how about that for scientific, I forgot the exact term :D). I don't think it was capilarity, this would sound to simple...but sometimes the best answers are simple! :D


My webpage (http://www.wyx.com/iheo/tank/aquarium.htm) Updated 3rd July 2000

07/20/2000, 07:40 PM
Tagged for the archives

07/20/2000, 11:27 PM
To eliminate the possability of the caulerpa going sexual on you why not ditch the caulerpa and go with an algae that won't?

07/21/2000, 05:33 PM
Knowing from FW planted tanks how they love CO2 I got this cool idea this week to let the effulent line from the calcium reactor drip in the algae tank/refugia and maybe the macro algae will consume the excess CO in the effulant and that will help the tank PH. Am I crazy or is this a good idea. :confused:

07/22/2000, 05:05 PM
I was just thinking about that today just before I hooked up my refugium. I thinkit would be the best place to place it.

07/24/2000, 10:40 PM
Sorry this is such late reply Snailman, but yes that would be an excellent idea. Cutting back on circulating CO2 (which the CAR effluent going into the caulerpa tank would do) would allow a higher (more basic) pH. From what I've read, CA reactors can be tough on pH. Not only that, but I'm guessing the caulerpa would grow much faster (increased metabolism=increased nutrient consumption/export). At least its been my experience that photosynthetic plants in a hydroponic environment grow at an extremely accelerated rate. I'm sure that would apply to caulerpa as well. JM .02


07/26/2000, 01:44 PM
Hey RWD - For my 180 gal tank I have a 10 gal tank set up as a scrubber/refugium and I run it in a hybrid between 24/7 and RDP. That is, I have six 15W florescent grow bulbs built in a "cage" around the tank: two above, and two along each long side (About 9-10 watts/gal). The two above the scrubber are on 24/7, and the remaining four come on at night. Thus, the rate of photosynthesis should be greater at night to help stabilize pH, but the fact that the scrubber sees no completely dark period helps with preventing die-off. So far so good -