Reducing flow at night for SPS?

[29bonsaireef]

Not true, I do night fish weekly and there’s a significant change. I’m also an ocean engineer. I guarantee there is a difference.

I have no doubt you see a change in the surface, but it's what's beneath, where the corals are growing. If you've ever been to Indo, Fiji, Bahamas or any archipelago where corals are abundant, specifically SPS. The flow is enormous from tides pushing between the islands, and reefs. Really has nothing to do with waves at all, or surface movement. I have no problem with someone reducing flow in their system at night, but don't want them to think that's the natural way of a reef.

 

[Act1n1c_L1fe]

Unless your nightfishing on the actual reefs there is a difference. What does an ocean engineer do? Sounds cool.
Either way this argument goes I don’t think it makes much of a difference in a reef tank. When I kept high flow 24/7 my fish were defiantly healthier and stronger than when I have had the same species in small tanks with lower flow. And they found spots to rest either way with no issues.

I’m qualified to do many things. Build bridges, oil rigs, boats. I engineer center console boats

 

[Act1n1c_L1fe]

I have no doubt you see a change in the surface, but it's what's beneath, where the corals are growing. If you've ever been to Indo, Fiji, Bahamas or any archipelago where corals are abundant, specifically SPS. The flow is enormous from tides pushing between the islands, and reefs. Really has nothing to do with waves at all, or surface movement. I have no problem with someone reducing flow in their system at night, but don't want them to think that's the natural way of a reef.

I have been to the Bahamas... have you ever been caught in a wave? Especially in a shallow area? It’s a quick surge of energy which rapidly increases turnover (flow) when waves calm down, this energy depletes. Yes, in deeper water then 6 feet the waves can’t be felt but most of our tanks are no more then 24 inches tall. And in two feet of water, waves make a tremendous impact

 

[Pete_the_Puma]

From a fair bit of sailing I can say with certainty that waves/wind are for sure much calmer at night, on average. What that means for flow down in the reef I cant be sure.

To be honest I'm surprised the poll is 50/50 right now, I was almost certain the "reduce flow at night" premise would win hands down...

 

[29bonsaireef]

Well I don't think anyone has "waves" in their tank? The only point I am trying to make is flow does not stop on a reef. Day or night, stormy or dead calm, the corals are always receiving tons of flow, from the tides and currents.

Like I said, I have no problem at all if someone chooses to reduce flow at night, it's just not natural, but most tanks today are far from natural anyhow..

 

[Act1n1c_L1fe]

Well I don't think anyone has "waves" in their tank? The only point I am trying to make is flow does not stop on a reef. Day or night, stormy or dead calm, the corals are always receiving tons of flow, from the tides and currents.

Like I said, I have no problem at all if someone chooses to reduce flow at night, it's just not natural, but most tanks today are far from natural anyhow..

Yes. There is always flow. There is never dead flow. Coral reefs always receive flow. However, flow does decrease at night because waves die down.

 

[2una]

I throw fishing gear in the ocean that just drifts around for a living & current dropping because of day/night i'm voting a big no.

 

[w2inc]

I have a set of mp-40's and a couple 10. They all run at 87% +. When I saw the option to turn them down at night it made no sense to me. I went to college in Hawaii and we would go body surfing when it was a full moon and we could see well enough at night. We would also surf at night at a resort called Turtle Bay that had a big spot light on a small break we liked.

That was in 87, so my memory could be far from reality at this point, but I just don't remember the ocean taking a break. I am in San Diego now and up until 3 years ago we would lobster dive at night in the rocks just past the wave break line. At midnight the waves were still pumping hard and some nights it was scary to fight through them.

I am not an ocean engineer and I have never looked at data on it. This is just how the water feels to me. The waves could be smaller at night and they just seem big because of the dark and fear of death and all. The one thing that is sure is that there is no off switch on the pacific coast.

I don't turn things down at night. I had not thought that the fish might need it. When I use to spear fish at night, we would always look under rock structures and in holes where the fish were sleeping. The predators would be out, but the majority of the fish seemed to have found shelter.

I actually run a storm surge starting at midnight for an hour to blast things out of the areas that might have been overlooked by the normal flow. Damsels, firefish, tangs, gobies, and blennines all have caves and holes they go to at lights out. Firefish all share the den of the shrimp goby. My dragon face pipe fish, neon goby and cardinals stay out at night. I am not sure when the cardinals sleep. They have territory they could hide in but don't. I think there is a plankton rise at night or the storm surge blows pods off the rocks because they are always actively feeding when the lights are off.

I guess turning down the flow might make it easier for my corals to pull some of that plankton out of the water column. Seems like it is worth considering now that I have typed it out. What goes on in nature isn't always what is easiest on or best for the plants and animals (or humans). Thanks for posting. It gave me good stuff to think about.

 

[DesertReefBoy]

I personally believe varying strong/weak, random flow is best for SPS. I don't think it is necessary to turn the flow down at night. this is based off shining my light into the tank at night and seeing the SPS polyped out. the fish all find places to tuck into and all the shrimp in my tank along with the other CUC don't seem to be stressed when they are scavenging around.

 

[VR28man]

How about the actual tide charts from one place that has loads of SPS.

https://tidesandcurrents.noaa.gov/noaatidepredictions.html?id=1612301&legacy=1

Flow does change; it's strong (and in the forereef with the heavy sps coverage, often to the point where it's not that fun to swim). And when the tides change it changes direction. When you go down past a certain depth, say 60 feet or so, the tidal effect can be much less, and flow can be even linear. It depends on the ocean geography of the area.

That being said, in nature the amount of flow and light an average coral colony gets, even in the tropics, can vary due to weather (to include days without lots of light). Obviously, randomly decreasing the amount of light is not good for your corals.

For my part, I always use tidal swell mode on my MP40s, and vary the intensity a bit day to day, and turn it down 2-3 notched at night ( unless I decide that there should be a storm either day or night ). I run NTM daily, and have sometimes forgotten to turn it off for several hours.

ETA: on the forereef, in addition to tidal flow there’s a lot of random flow, at least at the first 15 feet or so of deptg. Also, it’s very clear that you can grow coral very successfully with a constant amount of random flow in an aquarium.

And yes, the amount of flow and waves is generally less at night that it is during the day. At least at the surface, due to a number of weather related factors, I believe.

 

[Pete_the_Puma]

Well I have to say I am blown away, was sure this thread would go 90% of people saying they reduce flow and it was a dumb question... Seems like it is almost a 50-50 split, which tells me there is probably no great difference one way or another or the community would have figured it out. I guess I'll start out with everything on all night long and see how things go!

Thanks everyone for contributing!

 

[Pete_the_Puma]

I throw fishing gear in the ocean that just drifts around for a living & current dropping because of day/night i'm voting a big no.

Wait I just want to make sure, when you say you are voting a big NO you mean in your experience there is NO difference between the intensity of currents during day/night?

 

[Bob Weigant]

I do reduce the flow at night in my sps tank. I have no scientific facts to back why I do it just a preference.

 

[Dugless]

While trying replicate nature is honorable, it is just unrealistic in so many ways. Especially in the aquarium sizes most all of us are dealing with. I keep the strength of my flow constant as it encourages proper coral growth form and provides the best oxygen and nutrient delivery for my tank inhabitants.

 

[2una]

Wait I just want to make sure, when you say you are voting a big NO you mean in your experience there is NO difference between the intensity of currents during day/night?

yes daytime or nighttime has nothing to do with it, tides go up & down & stronger or weaker because of the gravity between the earth & the moon and the sun.
Offshore its more just current related than tidal but strengths change mostly due to the state of the moon.
Is kind of covered here https://www.timeanddate.com/astronomy/moon/tides.html
and here https://oceanservice.noaa.gov/education/tutorial_currents/02tidal1.html

Tidal currents are the only type of current affected by the interactions of the Earth, sun, and moon. The moon’s force is much greater than that of the sun because it is 389 times closer to the Earth than the sun is. Tidal currents, just like tides, are affected by the different phases of the moon. When the moon is at full or new phases, tidal current velocities are strong and are called “spring currents.” When the moon is at first or third quarter phases, tidal current velocities are weak and are called “neap currents.”

 

[VR28man]

I left TSM at eight last night (30x13x18 inch tank) and woke up to see this this morning. I overfed the curls a little bit last night, I wanted some more flow. That being said, most of the fish are out, except for the fire fish which has been skittish ever since I added the Royal gramma last week.

I thought about this thread When I saw them swimming into the current, even though it’s not really relevant to it.

 

[revhtree]

Good thread!

 

[Softhammer]

I have done many night dives in the Caribbean and many more in the Indian and Pacific Ocean reefs and unless there is a storm the flow is significantly less at night. Still a surge but no where near daytime surge. All corals polyps are extended at night and that’s when the bulk of their feeding is done. Plankton is everywhere at night and with the lower flow you can actually see food being caught. That’s what I replicate in my reef with my Tunze controller. Also the moon light with its cycles is great too. Since using it I have had Acropora spawning events on 3 separate occasions over the years as well. To each his/her own but after hundreds of dives over a 20 year period, that’s my story and I’m sticking to it!

 

[FlyPenFly]

People who night dive, do you think maybe it's calmer because you go out on nights where it's calmer? In day time, you're probably going when it's a windier or heavier day.

 

[Softhammer]

No. Unless there is a storm it’s calmer. Winds typically slow at night due to seebreezes waning from lack of suns heating. Certainly there are thousands of exceptions to this, but it’s generally calmer at night if no weather systems are present. I also night fish on my boat here as well as dive and I’m sure there are many boaters also that can corroborate my experience. I’m sure someone’s going to mention tides, they do not stop at night obviously but a tidal exchange is a much more laminar flow than what wave and wind actions create.