Reduced Circulation At Night?

[ChrisRD]

I'm running a closed loop with two sea-swirls at the outlets on my 50 reef. Flow is very good (the SPS seem to love it), but I'm wondering if it would be beneficial to put the loop on a timer so that I have a period at night (I was thinking maybe 6-8 hours) of low flow.

I'm thinking the Xenia and LPS corals might benefit from this (I've already located those species in the lowest flow parts of the tank, but full flow still seems a bit much for the Xenia). I would still be at about 10X circulation WITHOUT the loop running. With the loop running I'm at about 24X. Thoughts?

 

[Leopardshark]

probably your corals will be fine, I´ve heard of many people doing so, in my case I haven´t done it but I think it is a good idea, even do I don´t know if at night the sea is more calmed or not.
Try it and inform us about the results.

 

[wombat1]

Something in the back of my mind has always had a problem with the sea being calmer at night. Why is this??? I could see how onshore winds would decrease at night on a continental shelf, but what about corals on atolls in the middle of the ocean??

 

[rishma]

A few thoughts:

I have considered doing this also. I know for certain the reefs and beaches I have frequented are much less windy at night and in the early morning, but I am no oceanographer. Any surfer will tell you that wind contributes significantly to the wave action near shore.

(a side note) Tunze brand Turbelle® circulation pumps have an optical sensor with the controller that actually slows down water movement when the lights are off.

Power savings would be a great side effect, but turning a pump on and off daily will likely shorten the life due to motor/impeller wear.

I hope this thread gets some more attention.

Cheers,

 

[King Jason]

Well I live about a quarter mile from the beach and I can tell you there is defiantly wind in the day and not so much at night.

I also have a condo on the beach in Maui, and you can defiantly tell the current is weaker at night and in the early morning. I can tell because the water is so much clearer then it is at around noon or later.

I think that this is a good idea, however, like rishma said turning the pump on and off every morning and night would shorten it's lifespan.

 

[esmithiii]

Keep in mind, though that at night there is not photosynthesis. The major byproduct of photosynthesis is O2 (Oxygen.) Reducing circulation at night will further lower the oxygen levels and increase pH swings. Personally I don't think it is worth the energy savings. Your corals need good gas/waste exchange at night too.

The current on real reefs is much higher even at night than in our tanks day or night.

 

[rishma]

esmithii brings up some good points. In the absence of photosynthesis the O2 production decreases and consequently the pH drops. Less water movement could amplify the nightly pH swing.

With a refugium illuminated at night, the pH swing is controlled and I doubt the decrease in closed loop circulation would be noticed (in regard to pH that is).

I cannot say for certain if nighttime reef currents are more or less than the current in any given tank. If the current in your tank was sufficient for good waste transport during the day, would 8 hours of less current adversely affect any corals?

I think this may be a question best answered with a trial period.

 

[esmithiii]

With a refugium illuminated at night, the pH swing is controlled and I doubt the decrease in closed loop circulation would be noticed (in regard to pH that is).

My reverse lit refugium (2x65W LOA flourescents) is no match for my daytime lighting (3x400W 6500K MH + 4x96W PC Actinics) and there is a significant pH swing.

 

[Carpentersreef]

I imagine that without sufficient water circulation, your LPS will not be able to rid themselves of the slime coat that they excrete, and I think that that will leave them susceptible to infections like protozoan or brown jelly type.

Mitch

 

[azreefer]

Is this "brown jelly" your talking about something that moves from one branch to the next killing the entire coral? I had some frogspawn that died a couple days ago. I saw a brownish slime on the head of one branch and that day the polyps died. It migrated over the entire coral within the next few days and entirely kiiled it.

As for the ph issue at night, would it help to get an airpump and turn on a couple of airstones at night to help the oxygen levels?

 

[esmithiii]

AZReefer- I am sure it would help, but my response is to keep the same circulation day and night.

 

[Anonymous]

I agree that you should keep the water motion up at night. The lowered o2 levels(which also lowers the Ph), as well as bacteria settling when currents are low. It is nice to mimic much of nature in the captive system. However, there are differences between the systems that do not make it practical. The mass of the ocean compared to the mass of our tanks is the biggest reason.

 

[Leopardshark]

Well, in my case I wouldn´t turn off the iwaki of my closed loop, but I would turn off the wave maker. I don´t think that would be too much of a difference but maybe it would help the corals to have a more natural enviroment without compromising the overall parameters of my tank.

 

[ChrisRD]

Thanks for all the great feedback. I'm going to leave the loop running 24/7.

 

[ChrisIsBored]

Good idea... I'm thinking of getting a reeftec and during the day it will probably be going on and off at one minute intervals but at night it would probably be a good idea to change it to go off every 5 minutes or so maybe.

 

[Carpentersreef]

Is this "brown jelly" your talking about something that moves from one branch to the next killing the entire coral? I had some frogspawn that died a couple days ago. I saw a brownish slime on the head of one branch and that day the polyps died. It migrated over the entire coral within the next few days and entirely kiiled it.

Yes, that's the one. It can be cured with iodine dips and siphoning off the infection, but once the coral has it, it's tricky, because the brown jelly will re-infect the compromised tissue overnight. Low water flow will only allow the infection take a hold again.

Mitch

 

[azreefer]

I recently learned about the iodine dip but it was too late for the frogspawn. Thanks for the info! If I ever see it again I'll know what to do.

 

[Anonymous]

i used to reduce the flow in my tank for one main reason:i wanted my corals to be able to take advantage of my plankton blooms at nite.though the water still had moderate current.

try reducing it abit, and see what happens, i doubt if anything will suffer at all :wink:

 

[esmithiii]

i used to reduce the flow in my tank for one main reason:i wanted my corals to be able to take advantage of my plankton blooms at nite.though the water still had moderate current.

I don't folllow your logic. I am not sure how slowing your pumps down would accomplish that.

Ernie

 

[ChrisRD]

One of my original concerns in thinking a low flow period at night would be helpful (and I think this is what Vitz might be referring to here) was that LPS corals like my new bubble (which I target feed) might not get a chance to "hold on" to stuff with its feeder tentacles in the really high flow. I was thinking a moderate flow during the evening feeding time would be helpful for it. Currently I'm just turning off my closed loop during the feeding and for about 15-20 minutes afterward to give it a chance to pull everything in.