Current flow at night

masonicman · #1 12/04/2007, 09:52 AM

Ok I just found out something new. Who cuts back there power head/water flow at night and if so what are the pros and cons if any? I'm trying to decide if it is worth it or not to buys timers for my power heads in order to reproduce this night simulation.

Turbovinny · #2 12/04/2007, 10:00 AM

high/low/slack tides all happen at night too so a timer would help simulate the tides, i run 2 modded MJ1200 and 2 HK4 in a 110g without a timer and everyone seems happy

landlord · #3 12/04/2007, 10:01 AM

I believe it is a feature of the powerheads I use so I guess, I do. Would I go out of my way to reproduce a nighttime mode, probably not. I have no idea if there are any pros or cons.

FWIW --landlord

Rosseau · #4 12/04/2007, 10:20 AM

Well, a large part of keeping high flow onto SPS in particular is to discourage competitive algae to grow onto the corals... right?

I don't know exactly how these algae work, though I feel it may be safe to assume that require light in order to colonize the surface of a coral. Maybe not, maybe they can attach at night and then just grow during the day......

reggiepe · #5 12/04/2007, 11:34 AM

I have all of my flow reduced for the night after the last light goes out. Just the flow from the sump is the only water movement.

marcsmith73 · #6 12/04/2007, 11:40 AM

Same here. At 12 midnight Est time the Ocean Motions kicks off, and the Sequence dart powering it is off. At 10 AM it kicks back on...

I am also intrested in knowing what advatages or dis advantages this cycle may bring.

I have a G6 skimmer in the sump, and run a Barracuda for the return.

I mostly have SPS, and LPS.

Following along on this thread I guess.

~Marc

tkeracer619 · #7 12/04/2007, 11:45 AM

I leave all my stuff on 100% of the time.

Flow in the ocean is not caused by sunlight.

hyperfocal · #8 12/04/2007, 11:51 AM

At night, oxygen production decreases and oxygen consumption increases leading to reduced oxygen levels in the tank overall.

Studies have shown that inadequate flow around coral colonies leads to a thin hypoxic 'sheath' of water around corals, resulting in stress and worse.

Based on this, nighttime seems like the *worst* possible time to reduce flow. Oxygen levels are already reduced overall, lowering flow makes it that much harder for corals to get oxygen. Why stress your livestock when you don't have to?

sk8rreefgeek · #9 12/04/2007, 12:02 PM

I too have wondered about this, and have turned off my current pump a few nights cuz I thought the fish might "sleep" better. But I agree with tkeracer619 that current isn't caused by sunlight...but doesn't the moon affect current and tides???
hmm, for now I'm just gonna leave it pumpin. There's a guy on here with a quote that stands out in my mind "only dead fish swim WITH the current"

idk, someone outta get out there in the ocean at night and check the current status

tkeracer619 · #10 12/04/2007, 12:06 PM

Quote:

Originally posted by karlkidd
...but doesn't the moon affect current and tides???

Yup, and its still moving... or was that us? Or is it both?

I think

flameangel88 · #11 12/04/2007, 12:24 PM

I read that oxygen level is lower at night so I leave all the pumps running at night but perhaps we can reduce the flow rate a bit instead of shutting them down completely.

Quote:

Originally posted by hyperfocal
At night, oxygen production decreases and oxygen consumption increases leading to reduced oxygen levels in the tank overall.

Studies have shown that inadequate flow around coral colonies leads to a thin hypoxic 'sheath' of water around corals, resulting in stress and worse.

Based on this, nighttime seems like the *worst* possible time to reduce flow. Oxygen levels are already reduced overall, lowering flow makes it that much harder for corals to get oxygen. Why stress your livestock when you don't have to?

LooklikeME · #12 12/04/2007, 12:34 PM

I saw the light and had to chime in.I only shut my pumps off for feedings. At nighttime they reduce to 30% but never off.

masonicman · #13 12/04/2007, 12:38 PM

I have 3 power heads I was think about shutting 2 of them off at night. I also have the return from my canister filter that also has a pretty good flow.

Pmolan · #14 12/04/2007, 01:16 PM

I have the return pump and 4 MJ 1200 at night and the day I use them plus the H4's.

davocean · #15 12/04/2007, 01:44 PM

Being a night time lobster diver I can tell you current can be more or less, depending on tides, outer ocean storms, and other stuff much more than day or night time.
In fact, I've dove in the afternoon b4 w/ ocean very calm, and dove again later at night on same day, and had trouble even staying in the same spot due to current being so strong.
I keep my tank flow 100% at all times.

masonicman · #16 12/04/2007, 02:44 PM

The diver Davocean decides it for me. Thanks all. I'm running mine a 100% of the time.

Indyws6 · #17 12/04/2007, 04:06 PM

Greetings

I have 3 400GPH powerheads, all of which are on a wavemaker function provided by my controller.

Two of them are on at the same time and water flows from them in a direction that opposes the flow from the return pump (CCW)

The other is on when the first two are off and water flows from it in the same direction as the return pump (CW).

The cycle time is set to 10 minutes (the first two are on for ten minutes while the single one is off, then it switches and the single one is on for ten minutes while the first two are off...).

The controller, by default, doubles the cycle time to 20 minutes while the lights are off and I left it that way thinking that they must have designed it in that fashion for a reason

The amount of water flow does not change, only the frequency of the wavemaker function. Essentially, it produces a longer tidal period during the "night" time...

usefulidiot213 · #18 12/04/2007, 04:34 PM

Well so far we have learned that O2 levels are lower at night, and that day light has nother to do with tides. From personal experence I know the ocean moves just as much at night then it does during the day. SoOoOo I don't really see any reason to lower the flow at night other then maybe saving a few bucks on the ernergy bill....

sk8rreefgeek · #19 12/04/2007, 05:11 PM

haha, I knew someone out there has been in the ocean at night, and would provide an answer. thanks davocean

greenbean36191 · #20 12/04/2007, 06:21 PM

Currents can be less at night due to less onshore wind, but unless you're somewhere with otherwise still water the effect usually isn't noticeable. Usually tides and the surf are going to be the major factor controlling flow on the reef and there's no reason they can't be just as big at night as during the day. I had to call off my last night dive due to the currents.

Hyperfocal hit the biggest issue right on the head. Even in the wild the water within the branches of corals can become hypoxic at night and the boundary layer (the thin layer of water sticking to the coral's surface) is almost always hypoxic.