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

[gman2]

I ask this because I notice that some of my SPS seem to be smooth on one side compared to the other. They get the same amount of light on each side. Also I have others that seemed to have the growth stunted as they are smooth all around. The polyps only extend at night on a couple of the smooth sps.

I assume its a current issue but I have alot of water movement.

I have a 180 with 2 seaswirls for returns. Two large Tunze powerheards that are variable speed. 3 maxijet 1200's, 2 maxi 900's and 2 maxi 600's.

I just bought a redsea wavemaker to put the powerheads on.

Thanks for any input
Tony

 

[CraigLampe]

Wow, that sounds like a lot of powerheads compared to my tank, though I have a 125 and probably deserve MORE WATER MOVEMENT...

I have a lot of SPS and I often note that for them to be happy, they need water a certain amount of water flow, they DON'T LIKE DIRECT POUND ME-type water flow, this will kill the side of the coral facing the powerhead, but I like to see the little polyps wiggle (from water movement) every couple of seconds... I find it is a good method to place a coral so it "just misses" a DIRECT JET from the powerhead/pump... this creates an ebb/flow phenomenon which my corals love, it is also a bit RANDOM, because I have no wavemaker sorts of devices, only powerheads which are on ALL THE TIME... this positioning gives my SPS some RANDOM variation in the amount and direction of water flow...

 

[Anonymous]

"I find it is a good method to place a coral so it "just misses" a DIRECT JET from the powerhead/pump"

The phenomena is called viscous entrainment. The actual jet is pulling water alongside it due to the viscous nature of water. Tidal currents are so strong on reefs that many leuconoid reef sponges actually use viscous entrainment to pull water through flagellated chambers faster than choanocytes can pump it.

In general, your velocity is not as important as your overall flowrate. You want as much water moving through the tank as possible. The most important energies on coral reefs are east to west tidal currents caused by tidal waves moving around the planet. They are responsible for any and all export of productivity. The ONLY random currents on a reef are those deflected by structure to create microhabitats (ie, those between Acroporic branches), and even then, they still have the same general vector as the overall flow direction. Randon water motion is incomparable to unilateral, high flow. Very good overflow/return pump capacity is important. Surge devices are nice but not always practical. The recently praised "closed loop" is also a good idea. Powerheads are not.

 

[Anonymous]

Randon water motion is incomparable to unilateral, high flow. Very good overflow/return pump capacity is important. Surge devices are nice but not always practical. The recently praised "closed loop" is also a good idea. Powerheads are not

so the powerheads aren't recommended even with a wavemaker?
other than problems of them not restarting and being ugly, what's the disadvantage? it seems a few PH turning on sequentially would create a random flow (well, random as other means, like a sea swirl).

 

[Mac1]

The phenomena is called viscous entrainment. The actual jet is pulling water alongside it due to the viscous nature of water. Tidal currents are so strong on reefs that many leuconoid reef sponges actually use viscous entrainment to pull water through flagellated chambers faster than choanocytes can pump it.

Bawh?
Gawhh...

Yeah, what he said?!?!??!

WOW! Now there's some 25-cent words you won't find in just any dictionary. Thanks for improving my vocabulary!

Anyway, yeah, what they all said is right Don't blast the corals w/ a jet from a PH, but rather position two to blow towards each other, or just past a stand of Acro's.

I'm in the planning stages for a new tank, and am figuring on 3 SS's, and 3000 GPH through the return pumps, as this will be a dedicated SPS tank. It's also looking to be a 180 gal (since Oceanic's 200 is friggin expensive!). I've noticed over the years, of watching lots of video's and footage from diving expidition's on the reef, that we get nowhere's near what's found in nature, when it comes to flow. If you really look closely at some movies and stuff from underwater, you can get a good idea of just how much movement really takes place underwater. Especially on the bottom: Riptide's are rather strong indeed.

- Mac

 

[esmithiii]

they DON'T LIKE DIRECT POUND ME-type water flow

Last weekend I was snorkeling in Puerto Rico (I had to be there over a weekend on business) and two weeks before also. Both reefs were quite diffferent, on being in the Atlantic and the other the Carribean. The current flowing over most SPS and gorgonians that I saw was so intense that the polyps seemed to me like they would be blown off! The corals were nonetheless quite healthy and large.

After seeing that, I am under the impression that up to recently I had no where near enough flow, and even now that I have installed a closed loop, I still think I could use some more flow.

As for random currents, most corals I saw got blasted in primarily one direction (and some the reverse also,) which is what I believe Galleon is saying. Now I am not sure I needed the sea swirls after all

Ernie

 

[Anonymous]

Right on Ernie.

Podman, I wouldn't recommend powerheads at all, especially if they are on a wavemaker or seaswirl. Random, chaotic currents are not what reefs experience. They only occur in microenvironments created by structures like microatolls or within the branches of corals. Give a tank strong, high flow high turnover in one direction, just like in the wild, and any randomization that occurs (if any, considering how small most of our corals are and how basic most of the aquascaping is) will be natural. In any case, you really can't provide enough flow in the tank.

 

[esmithiii]

The only reason why I might still advocate using sea swirls is that in my tank getting good flow to all points in the tank at all times is near impossible (A surge device would be ideal, but my wife won't go for it) so the swirls do a good job of making sure there are no dead spots.

 

[Anonymous]

Be sure to note the terms used. Flow and velocity are 2 different things. FOr instance, using the same amount of water through a 1/2 and 1" piece of pipe. The flow will be the same, but the velocities will be very different.

 

[Anonymous]

Yup. I was consciously using the word flow. Thanks for the talk down pal.

 

[Anonymous]

Not sure how to take that, galleon. I was trying to point out the difference. I know you know, but there are others that may not. Sorry if I upset you, and if I didn't maybe I need to learn how to read

 

[Anonymous]

...not like it sounded.

We've always used talk down two ways, one in the derogative way, and the other to mean an explanation of something like a jargon term. I meant the latter

 

[esmithiii]

Steve- I think that is what Chris meant when he said "In general, your velocity is not as important as your overall flowrate."

so the powerheads aren't recommended even with a wavemaker?
other than problems of them not restarting and being ugly, what's the disadvantage? it seems a few PH turning on sequentially would create a random flow (well, random as other means, like a sea swirl).

Random flow is not necessarily what you are after (if I read Chris right.) You are after total flow. Powerheads pointed in a fixed direction turning on and off do nothing to increase total flow and they don't do anything to eliminate dead spots.

As I said before a surge device sounds ideal to me, but in my case it is not feasible. Sea swirls work well for me now.

Ernie

 

[Anonymous]

No problem 8)

Ernie,
I missed that and saw it after I posted. And agree.

 

[SPC]

Ok, now let me ask this question . A Sea Swirl rotating 90 degrees will place flow on a given object at the same point each rotation. Lets say it takes the Swirl 20 seconds to go from point A back to point A. A surge device is also going to have a slack period, if the time period (20 seconds) is the same as the Swirl, what difference is there? Every coral is not being hit by the flow at the exact same time, but every coral is being hit with same direction of flow each time. :?
Steve

 

[Anonymous]

...the airspeed velocity of an unladen swallow, of course.

Good point Steve, but, we're talking about a closed box. The properties of refraction dicate that if you something with energy in a lateral direction, some, if not much, of the energy is refracted...at a mirror angle as the energy direction being reflected. So, by interaction of the currents with each other and the physical properties of the tank, you get far more randomization than if you were pulling (entrainment) and pushing water in all the same direction, a common vector = a common reflected vector, and thus, less randomized flow.

 

[Anonymous]

so the powerheads aren't recommended even with a wavemaker?
other than problems of them not restarting and being ugly, what's the disadvantage? it seems a few PH turning on sequentially would create a random flow (well, random as other means, like a sea swirl).

Random flow is not necessarily what you are after (if I read Chris right.) You are after total flow. Powerheads pointed in a fixed direction turning on and off do nothing to increase total flow and they don't do anything to eliminate dead spots.[/quote]

pardon me for being stuck on this, but how do they "do nothing to eliminate dead spots"?

it seems they certainly would. if you put one on each side of a tank and intermittantly turned one and then the other on, this would create a back and forth effect, no?
if they were both on all the time, there would be areas where the flow remained constantly blowing in one direction. turning one off could eliminate "dead spots" by the current switching direction in that area.

i must be missing the point. i understand the discussion being had with movement being at different velocities and flow. just can't grasp why a wavemaker wouldn't create a more random flow albeit less flow than without.

 

[SalmonAlley]

This is exactly the type of discussion I was looking for regarding flow, and now I find myself hopelessly confused

But..lemme see if I got this..let's take the example of a standard 125 (6' long). According to galleon, the optimal flow through this tank would be high flow directed from one end of the tank, down the length of the tank, and (again ideally) exiting at the other end, allowing the corals and aquascaping to create any micro-randomized currents..yes?

If I've got the concept, my next question is more specific...let's say in that aforementioned tank, your internal overflow is located in the back panel...how can one achieve the type of flow discussed? and how does one keep from developing a sand bed which slopes precariously from one end to the other as sand is carried downstream?

Sorry if I'm being dense here, but this is driving me nuts! 8O

Thanks for the thread,
SA

 

[CraigLampe]

Well, SalmonAlley, this kind of slow laminar flow through the 125 would take EXTREME QUANTITIES of water flow, I mean basically if you have a pump capable of 1250 gal/hour, that STILL MEANS that it would take 6 MINUTES for water to enter the tank, drift and exit... I don't know if ANYONE has this kind of laminar "flow through" tank besides those connected to REAL SEAWATER!!

I personally think that the corals deserve WAY MORE FLOW than simply what my sump return flow is... this would clearly not be enough!!

 

[SalmonAlley]

Hi Craig,
I absolutely agree with you. I'm sure that the corals would appreciate more flow than what you've described. Perhaps I didn't articulate my question well. Lemme give it another shot :
What I am taking from this discussion is that the SPS corals (in theory) would prefer unidirectional, high flow to most closely approximate natural conditions. But from a logistical standpoint, how can I achieve this in a 6 ft 125 gal tank with the overflows drilled in the back? I would think that I'd have to align the returns just so, AND add a closed loop, and even then, I think there will be sand issues.

SA