How do you know when you have enough current for sps?

[CraigLampe]

I must disagree in a way with the comment that HIGH VELOCITY IS BAD... I think it is OK, as long as you DO NOT POINT THIS AT CORALS DIRECTLY

I use an 802 going full-bore wide-open but I point it toward the front glass so it "misses" all of my sps but creates the "viscous entrainment" phenomenon

 

[aquarist=broke]

I use an 802 going full-bore wide-open but I point it toward the front glass so it "misses" all of my sps but creates the "viscous entrainment" phenomenon

Probably blows the substrate all over the place.......

 

[wombat1]

Surge makers are the way to go. Ever since I saw one work I won't create a tank without one. I think it's much better to have a period of very high flow followed by relative calm than the piddly currents that seaswirls or wavemakers create. Although the surge is not constant, it will undoubtedly come closer to natural conditions in terms of washing away waste and detritus and exchanging oxygen and nutrients for the coral.

 

[npaden]

I agree that high velocities are not always bad if pointing away from hitting corals directly. What I'm trying to emphasize is that if you have a choice in setting up your plumbing that the larger diameter pipe is the way to go. For sure a powerhead placed strategically where it doesn't point directly at some corals is better than no powerhead. Given the option though I would rather have a larger diameter fixed plumbing setup without powerheads though.

FWIW, Nathan

FWIW, Nathan

 

[SalmonAlley]

when you're talking surge makers, what is a good rule of thumb for size of the surge reservoir relative to size of the tank?

 

[Anonymous]

I set up the Gemini in my 120, and while the water stayed in the tank it did stir things up quite a bit. The southdown substrate stayed in place but would have slowly got displaced, I think. Every cerith rolled across the substrate!

A 3/4 pvc fits right around the nozzle, so I should be able to try something.

 

[SalmonAlley]

How about if you were to use a PVC "T" piece. Attach the single end to the end of the Gemini. Cap the other two openings, then drill a line of smaller holes along the length of the perpendicular horizontal piece? Or maybe even just cut out a narrow, long rectangle?

 

[Anonymous]

I thought I might do that- just cut a rectangle hole the length of the t-piece with a piece left on directly in front of flow. But I found a 3/4 x 1 inch t - so I got that and I'll put 2 1" elbows on either end. Also I got a 2" fitting and cap to try a straight fitting. I will try to get some pics.

 

[wombat1]

when you're talking surge makers, what is a good rule of thumb for size of the surge reservoir relative to size of the tank?

I don't know. I just put a 5 gallon bucket at ceiling height, and plumb it with 1"pipe. This works well in my 40 gallon, but I would switch to 2" pipe for anything bigger. The height of the bucket and diameter of the pipe determines the flow rate. The size of the container determines the duration. Also, if you make it too big your overflow might not be able to handle it.

 

[CraigLampe]

Actually "aquarist=broke," the powerheads are hanging at some of the highest points in the tank, so it really doesn't get much current close to the sand enough to stir things up...

I do agree that bigger piping is better... my overflow to the sump is 1.5" diameter PVC!! UGH!!

I also try to keep all of the other piping that I design into the system as large as possible... I always make the "GRAVITY OVERFLOW" size BIGGER THAN the "PUMP-WATER-IN" size so gravity doesn't have to work too hard!!

 

[Anonymous]

Actually "aquarist=broke," the powerheads are hanging at some of the highest points in the tank, so it really doesn't get much current close to the sand enough to stir things up...

I do agree that bigger piping is better... my overflow to the sump is 1.5" diameter PVC!! UGH!!

I also try to keep all of the other piping that I design into the system as large as possible... I always make the "GRAVITY OVERFLOW" size BIGGER THAN the "PUMP-WATER-IN" size so gravity doesn't have to work too hard!!

hey Craig,

just so we don't have any confusion, bigger is not always better, right?

a 2" pipe is too big for a 500gph pump, that wouldn't allow any flow anywhere but the first inch out of the discharge.

i think we should clarify for those that may be watching.

and as far as gravity overflows are concerned we might clarify that the overflow tube itself should be sized so there is less air buildup inside the "J tube" portion(given an overflow box is used). if pumped out of the sump, there will be no additional restriction by sizing down in the overflow. it would be fine to oversize from the overflow box down to the sump, which is what i believe Craig is saying.

just nitpicking :wink:

 

[Anonymous]

Well, unfortunately, it should be that easy, but surge isn't the dominant and most morphemetrically active energy on reefs. Anybody know what is?

Chris

 

[SPC]

Tidal currents?
Steve

 

[wombat1]

I've tried my hardest to figure out what "morphometrically" means; I still think a surge bucket is the easiest way to come anywhere close to the forces a coral might experience on the reef.

 

[Anonymous]

School boys :roll: :wink: Before you tell us the answer to the question, tell us whant morpemetrically means :lol:

 

[esmithiii]

No answer as of yet on the vocabulary quiz?? I looked on-line and through all my dictinaries and did not come up w/ a definition of morphemetrically nor morphemetrical nor morphemetric

Galleon- Don't leave us hanging, man!

Ernie

 

[MattM]

I can't find the reference now, but I had read a recent study on water flow rates around corals. One of the findings was that moderate flow rates resulted in polyp extension all around the coral for feeding and very high, direct flow rates caused the polyps upstream to close. However, eddy currents caused food particles to loop around the coral and be captured by extended polyps on the downstream side. I believe more total food capture was obtained in the higher flow.

The key is to reverse that strong direct flow regularly (like tides!) to allow the upstream and downstream polyps to reverse roles.

 

[Anonymous]

Yes, Steve, its tidal currents. Morphometrically is dealing with the measure of shape.

Matt, tidal currents don't reverse except in bays and behind spits to actually allow water to escape. Tidal waves travel in the same direction, always, around the world (the wavelength average is about half the circumference of the earth, but varies relative to the position of the earth around the sun and the moon around the earth). They only slack. Over barrier reefs and fringing reefs, the water doesn't move in the opposite direction "going out" as it did "coming in", the currents hold the same direction of travel, but are just offset to go around the blocking landmass. The direction of offset is dependant on the shape of the coast with smaller islands/landmass and by the Coriolis effect with larger, continental landmasses.

Chris

 

[MattM]

Matt, tidal currents don't reverse except in bays and behind spits to actually allow water to escape.

Chris -

If I remember right, that's exactly what was happening. They were looking at corals on the reef crest, and the currents reversed twice daily as the lagoon behind filled and emptied.

I'll keep searching for the original study...

 

[Anonymous]

hmm... I'd be very interested in reading this. Mostly, to keep going, the tidal wave would follow the path the path of least resistance, so it would just be deflected parallel to the reef, or force over the reef crest (tidal bulge) at high pressure. Unless the lagoon is a bay (ie, a semi-closed atoll), then we could see reversal and emptying.

Thanks for looking
Chris