Tank flow questions

[Somrschool]

But, Jim, weren't you surfing ON THE SURFACE? How much of the back and forth of wave motion went down more than a foot or two below the surface (as opposed to tides)?

 

[jimwat]

<a href=showthread.php?s=&postid=10509079#post10509079 target=_blank>Originally posted</a> by Somrschool
But, Jim, weren't you surfing ON THE SURFACE? How much of the back and forth of wave motion went down more than a foot or two below the surface (as opposed to tides)?

This depends on the size of the wave and the depth of the water (there's a mathmatical relationship...but marine science class was a long time ago ). Anyway, I was never worried about the tide throwing me into the reef.

 

[JetCat USA]

seams to me most of the comments thrown around about flow on reefs are from people who obviously have never dived them. at low tide a significant portion of the upper reef is exposed to air, most of the corals are robust acros that are exposed and they constantly take a beating from the waves both when exposed and when submerged, as you dive you're constantly tossed back and forth and even have noticeable bidirectional flow at 20-30 feet depth.

 

[jimwat]

I wanted to mention that I like reefnut's setup. Mine is not too dissimilar, but instead of the using the SWCD to change the flow direction I have my Tunze on a rotating mount (WavySea) that has a speed adjustment. I also keep a PH behind my rocks to helps keep detritus from settling.

 

[jimwat]

<a href=showthread.php?s=&postid=10509252#post10509252 target=_blank>Originally posted</a> by JetCat USA
seams to me most of the comments thrown around about flow on reefs are from people who obviously have never dived them. at low tide a significant portion of the upper reef is exposed to air, most of the corals are robust acros that are exposed and they constantly take a beating from the waves both when exposed and when submerged, as you dive you're constantly tossed back and forth and even have noticeable bidirectional flow at 20-30 feet depth.

True, but I have also dived in areas that have very little wave movement (Bahamas) where it seemed that all of the water flow was tidal.

 

[talon4x4]

<a href=showthread.php?s=&postid=10508751#post10508751 target=_blank>Originally posted</a> by jimwat
So I do not need to worry about undertow while swimming in the ocean when the tide is coming in? Or going out?

Undertow: There is spirited discussion and disagreement among coastal scientists on the existence of a nearshore process called "undertow," and hence there is not an agreed on definition for this word. Undertow is a term often and incorrectly used for rip currents. The best explanation for what many people attribute to "undertow" is as follows: After a wave breaks and runs up the beach, most of the water flows seaward; this "backwash" of water can trip waders, move them seaward, and make them susceptible to immersion from the next incoming wave; however, there is no surf zone force that pulls people under the water.

 

[LobsterOfJustice]

<a href=showthread.php?s=&postid=10508624#post10508624 target=_blank>Originally posted</a> by RichConley
You misunderstand what flow is like in the ocean.


Flow is strong, and unidirectional. Waves are present on the surface only. Where your corals are growing, the vast majority of flow comes from tides moving in and out.


Huge unidirectional flow, switching directions every 6 or so hours.

Rich, I'm going to have to call you on this, this is just not true. I went diving last weekend (30-50 feet). The flow changes and alternates direction and intensity. At one point i found myself being washed back and forth 5 feet over and over, like I was in front of a giant tunze wavebox. Other times the flow went left, right, up, down whatever. I watched the coral sway back and forth, watched little areas get pulses of flow and then have the flow go slack.