Argument against reverse lighting cycle on a refugium

[Danny Venditti]

I have not seen any recent public updates.

Hello Trident!!!!

 

[Wrasse-cal]

So what do we get for the reverse lighting cycle, a little pH bump? But if we're growing macro algae, isn't most of the food being decomposed from ammonia during the day? So we're left with whatever remnants of nitrogen at the end of the day. Sure nitrate uptake will happen overnight, but wouldn't it be better to have the macro algae compete with the nuisance algae during the day? I can see if you have no algae in the tank to running a reverse daylight cycle, but really is a small pH bump worth the competitive disadvantage of higher nutrients during the night?

Thoughts?

Assuming OP's hypothesis is correct regarding the benefit of competing with photosynthesizing algae in the display tank and taking into consideration the O2 and pH stabilizing benefit of running a refugium on a reverse cycle, this would be an rationale for having two smaller algae reactors on opposite 12 hour light cycles.

Best of both worlds.

 

[Danny Venditti]

Assuming OP's hypothesis is correct regarding the benefit of competing with photosynthesizing algae in the display tank and taking into consideration the O2 and pH stabilizing benefit of running a refugium on a reverse cycle, this would be an rationale for having two smaller algae reactors on opposite 12 hour light cycles.

Best of both worlds.

My head just literally exploded!!!!!!!!;Wacky

 

[Davy Jones]

I still believe feeding time would be the peak time, and it trails off after that. It's true fish put out ammonia and poop through out the day, but all the junk from frozen food is a significant nutrient input and isn't processed by the fish.

Lets assume that feeding time adds a significant source of nutrients when it gets put in the water, and you run you tank lights on a 12 hour cylce. You could easly resolve this problem by having your fuge/reactor run on a 14 hour cylce, It comes on an hour and a half before your lights turn off for the day, you feed the tank an hour before lights out and the fuge is already up and running and ready to process the input.

 

[Ocelaris]

So here's my thoughts, ammonia is never measureable in a normal tank, so it's being consumed very rapidly, presumably as a preferred nitrogen source. So you would have to have your chaeto running all the time. I would like to see a brs comparison of 4 methods:

Reverse cycle
Daylight cycle
2 half fuges
14 hour overlapping cycle

This would help determine which is the best uptake method of ammonia before the algae in the tank gets it.

 

[Wrasse-cal]

So here's my thoughts, ammonia is never measureable in a normal tank, so it's being consumed very rapidly, presumably as a preferred nitrogen source. So you would have to have your chaeto running all the time. I would like to see a brs comparison of 4 methods:

Reverse cycle
Daylight cycle
2 half fuges
14 hour overlapping cycle

This would help determine which is the best uptake method of ammonia before the algae in the tank gets it.

@randyBRS, I'd be curious about the effect of 2 half size refugiums run on alternating cycles versus one large refugium on a reverse cycle to the display.

 

[Randy Holmes-Farley Verified Community Expert]

@randyBRS, I'd be curious about the effect of 2 half size refugiums run on alternating cycles versus one large refugium on a reverse cycle to the display.

What exactly would you measure/test to see if this was "better"?

I also don't see the logical rationale, but that's a different issue.

 

[Wrasse-cal]

Well, I'd be curious about pH stability/O2 as quantitative measurements. What would likely be somewhat qualitative would be whether there is actually a positive effect on the tank where the macro algae in the diurnal reactor/fuge is better able to out compete micro algae in the display tank. Possibly, the macro algae in the diurnal reactor/fuge could out compete corals for nutrients, so that might be an unintended and undesirable consequence of this method--assuming again that most coral nutrient absorption occurs during the day. Is this even known?

 

[Wrasse-cal]

@Randy Holmes-Farley, the value of the experiment assumes the following (which may or may not be true)

1. Coral intake of dissolved nutrients during the day is significantly more than at night. (If not true, this eliminates the need for the experiment)
2. Macro algae intake of dissolved nutrients during the day is significantly more than at night. (If not true, this eliminates the need for the experiment)

If these conditions precedent are not true, then you're right that there is no value to the split reactor/fuge experiment.

 

[Randy Holmes-Farley Verified Community Expert]

Well, I'd be curious about pH stability/O2 as quantitative measurements. What would likely be somewhat qualitative would be whether there is actually a positive effect on the tank where the macro algae in the diurnal reactor/fuge is better able to out compete micro algae in the display tank. Possibly, the macro algae in the diurnal reactor/fuge could out compete corals for nutrients, so that might be an unintended and undesirable consequence of this method--assuming again that most coral nutrient absorption occurs during the day. Is this even known?

FWIW, Eric Bornemann didn't study split cycles like you suggest, but he does show the effect on O2 of reverse cycles here:

http://reefkeeping.com/issues/2005-08/eb/index.php

"Using algae in reverse daylight tanks appears to be an effective means of keeping oxygen levels at normoxic levels at night. This effect is pronounced even in tanks and systems that employ protein skimmers and airstones."

 

[Randy Holmes-Farley Verified Community Expert]

@Randy Holmes-Farley, the value of the experiment assumes the following (which may or may not be true)

1. Coral intake of dissolved nutrients during the day is significantly more than at night. (If not true, this eliminates the need for the experiment)
2. Macro algae intake of dissolved nutrients during the day is significantly more than at night. (If not true, this eliminates the need for the experiment)

If these conditions precedent are not true, then you're right that there is no value to the split reactor/fuge experiment.

Coral nitrate uptake comments, where it seems higher at night than during the day (Figure 4 has a nice graph):

http://www.aoml.noaa.gov/general/lib/CREWS/Cleo/St. Croix/salt_river47.pdf

"There appeared to be a diurnal pattern in the rate of nitrate uptake (Fig . 2), although this was not significant at p = 0.05 (1-way ANOVA, 0.10>p>0.05) . The residuals of the regression of uptake rate on concentration are shown in Fig . 3 . This controls for the effect of ambient concentration on uptake rate, and suggests that uptake was depressed in the early morning (between ca 04 :00 and 08 :00 h) . A cyclic effect related to time of day was tested for using a Fourier series (periodic) regression, which significantly increased the determination of variance of the regression (F = 3 .78, 0.01>p>0.005 ; Sokal & Rohlf 1981). Simultaneous 95 % confidence limits were placed on the uptake rate estimate (Fig . 4), which do not overlap for the highest estimated uptake rates around 23 :00 h and the lowest shortly after sunrise (ca 06 :30 h) ."

 

[NY_Caveman]

I think what could be tested easily is the nutrient uptake of the chaeto by comparing growth rates. 24 hour vs. 12/12 vs. 16/8 like Randy’s test I posted above (which it seems found 24 hour was not optimal), but expand it to include a daylight vs. reverse vs. overlap comparison. The test could also additionally test a macroalgae reactor in each scenario and even include tests that use both a refugium and reactor. The combinations are many. I personally do not have the means to do the test.

 

[Ocelaris]

I have seen a few articles showing that oxygen limitations are part of the limiting factor on growth:

http://www.advancedaquarist.com/2012/12/corals2

I can't find the article right now, but someone did a study feeding corals at night versus day, and they found feeding during the day was more successful with corals, presumably because of limited oxygen at night compared to the day time. So I think Randy's point of oxygenation at night being more important than the pH is spot on.

But for nutrient up take, it still seems that a concurrently lit refugium would out compete in tank algae which is presumably absorbing nitrogen and phosphorus during the day. But this assumes light is required for nutrient uptake, and that's an assumption, not something I'm sure about.

 

[MnFish1]

FWIW, Eric Bornemann didn't study split cycles like you suggest, but he does show the effect on O2 of reverse cycles here:

http://reefkeeping.com/issues/2005-08/eb/index.php

"Using algae in reverse daylight tanks appears to be an effective means of keeping oxygen levels at normoxic levels at night. This effect is pronounced even in tanks and systems that employ protein skimmers and airstones."

The question would be - is it more normoxic if the refugium light is only left on
at night' vs 24 hours a day...

 

[MnFish1]

I have seen a few articles showing that oxygen limitations are part of the limiting factor on growth:

http://www.advancedaquarist.com/2012/12/corals2

I can't find the article right now, but someone did a study feeding corals at night versus day, and they found feeding during the day was more successful with corals, presumably because of limited oxygen at night compared to the day time. So I think Randy's point of oxygenation at night being more important than the pH is spot on.

But for nutrient up take, it still seems that a concurrently lit refugium would out compete in tank algae which is presumably absorbing nitrogen and phosphorus during the day. But this assumes light is required for nutrient uptake, and that's an assumption, not something I'm sure about.

It would depend on what is in the refugium - the size of the tank, the amount of corals in the tank, etc, the amount of feeding, My guess would be that depending on how much 'stuff' you want to remove from a tank with algae in a refugium vs. the amount of stuff produced, the optimal duration of light in a refugium will vary from tank to tank

 

[Justin....#JAMAS]

I know this is an older thread but i just wanted to say i turn my fuge light on in the morning when i get up and it turns off at night before i go to bed! My chaeto has grown tremendously and my nitrate never geta above 2.5ppm and ph isnt much of a swing at all! Has benefited me alot to run it during the day plus i get to keep an eye on it! Something about a hot bright light running when im asleep just doesnt sit well with my mind for some reason haha

 

[MnFish1]

how does it work in nature? Do the algae on the reef have a different schedule than the rest of the flora?
Preventing the natural ph swing - is probably not beneficial - or is it? (I guess that is the question).

 

[Scrubber_steve]

Something about a hot bright light running when im asleep just doesnt sit well with my mind for some reason haha

What about a hot bright light while your out at work during the day?

Running the fuge at night helps maintain 'normoxic' conditions.

 

[Justin....#JAMAS]

What about a hot bright light while your out at work during the day?

Running the fuge at night helps maintain 'normoxic' conditions.

I work from home lol

 

[BigJohnny]

So what do we get for the reverse lighting cycle, a little pH bump? But if we're growing macro algae, isn't most of the food being decomposed from ammonia during the day? So we're left with whatever remnants of nitrogen at the end of the day. Sure nitrate uptake will happen overnight, but wouldn't it be better to have the macro algae compete with the nuisance algae during the day? I can see if you have no algae in the tank to running a reverse daylight cycle, but really is a small pH bump worth the competitive disadvantage of higher nutrients during the night?

Thoughts?

That's not how it works as far as the nutrients. The chaeto is consuming them 24/7, not only during lights on.

For me my pH would drop at least .2 dkH at night without my refugium, so very significant imo.