Everyone's favourite flow types

[PJPS]

A quick poll to see what flow types are favoured in nano tanks.

[mitten_reef]

I ran a gyre in the old IM30, that was great. 

The current tank has a Nero5 with the random program, and a small IM MightyJet for the lower back side running constant to keep anything from settling.   

[Jaren45]

I'm a fan of nutrient export mode on vortechs, it's a combination of pulses, standing waves, and random constant flow

[PJPS]

12 minutes ago, Jaren45 said:

I'm a fan of nutrient export mode on vortechs, it's a combination of pulses, standing waves, and random constant flow

My personal fav :).  Whatever happens with 2 vortecs in antisync NTP is pretty glorious flow for a small SPS tank.

[TheKleinReef]

I’ve always defaulted to reef crest mode for my mixed reefs. I have more lps now and have been using lagoon which I quite like. I’ll have to change it when I get more sps but the lps really like it!

[mcarroll]

Where's the option for tidal flows? 

[PJPS]

17 minutes ago, mcarroll said:

Where's the option for tidal flows? 

V2 I promise.  Random broad and pulsing seems tidal

[PJPS]

On 1/26/2023 at 10:49 PM, TheKleinReef said:

I’ve always defaulted to reef crest mode for my mixed reefs. I have more lps now and have been using lagoon which I quite like. I’ll have to change it when I get more sps but the lps really like it!

Lagoon seems ideal for LPS.  My MP10 .mob files are in my journal thread, but for reference

 

 

 

[mcarroll]

1 hour ago, PJPS said:

V2 I promise.  Random broad and pulsing seems tidal

Hm.  Randomness is inherent to the rotating nature of the propellor pump, IMO (also quoting Tunze), so it's not really necessary from the programming.  Programming is very handy if you want to make waves happen though!

 

For "tidal" I'd say more laminar. Also tidal would be alternating on the scale of hours NOT minutes or seconds.  And I mean alternating directions, not just alternating ON|OFF.  👍

[PJPS]

23 minutes ago, mcarroll said:

Hm.  Randomness is inherent to the rotating nature of the propellor pump, IMO (also quoting Tunze), so it's not really necessary from the programming.  Programming is very handy if you want to make waves happen though!

 

For "tidal" I'd say more laminar. Also tidal would be alternating on the scale of hours NOT minutes or seconds.  And I mean alternating directions, not just alternating ON|OFF.  👍

I agree, although perhaps didn’t fully explain properly.  I’m of mixed ideas on laminar being tidal though.  To my mind tidal is gentle lapping waves, essentially.  So switching sides throughout the day, I do pulsing on one side against a mild reefcrest hoping to simulate small standing waves of slightly varying intensity.  Essentially a gentle shake froma one side then the other. Switching over ours in the morning and evening.  (I give this as anecdotal evidence since it’s what I’m aiming for, so I’m also willing to have my mind changed)

 

I guess it’s just how I picture it in my head.  I always think of laminar creating gyre flows in tanks.  In the ocean I agree, tidal flow has laminar flow, but it doesn’t create a gyre like it would in a tank.  So I skip laminar powerheads in nanos.

[mcarroll]

11 minutes ago, PJPS said:

I agree, although perhaps didn’t fully explain properly.  I’m of mixed ideas on laminar being tidal though.  To my mind tidal is gentle lapping waves, essentially.  So switching sides throughout the day, I do pulsing on one side against a mild reefcrest hoping to simulate small standing waves of slightly varying intensity.  Essentially a gentle shake froma one side then the other. Switching over ours in the morning and evening.  (I give this as anecdotal evidence since it’s what I’m aiming for, so I’m also willing to have my mind changed)

 

I guess it’s just how I picture it in my head.  I always think of laminar creating gyre flows in tanks.  In the ocean I agree, tidal flow has laminar flow, but it doesn’t create a gyre like it would in a tank.  So I skip laminar powerheads in nanos.

The flow rates of tidal flows can be pretty incredible, so I dunno about the "gentle lapping waves" analogy.  The "gyre" effect is more coincidental than anything...but it can certainly be used to good effect.  (IMO the word "gyre" is a bit out of place the way we use it.)

 

If I'm following you correctly, you have active pumps facing each other.  IMO they are canceling each other out, at least in part.  Better in most cases to run pumps that face each other in a manner where there aren't on simultaneously.  We want the turbulence to be created on the rocks, sand and corals, for cleaning and feeding purposes and the like – to break that boundary layer!!!  (Google "coral boundary layer"....but everything in the water has a boundary layer.)  We don't want turbulence just in the water for the sake of turbulence....that's a waste of watts. 

 

Turbulence is the opposite of flow.

 

Laminar flow eventually becomes turbulent, BTW.  As soon as it hits a hard surface (or opposing flow) of any kind, the flow splits, eddies, etc.

 

Check out: Oceanic Forcing of Coral Reefs. Please click through to read the source article.

[PJPS]

So in a 2’x1’ box it’s instantly turbulent?  This is a nano forum.
 

 Cancelling out the pulse, partly, is the point.  By setting the opposing pump to vary it’s speed from 0-30% moves the turbulence around that side of the tank.  It’s all done for a reason.  That reason being to break the boundary layer on that side of the tank.  Presumably the full force pulse handling the boundary layer washing in other half.

[mcarroll]

5 hours ago, PJPS said:

This is a nano forum.

Technically all tanks are nano tanks. 😉 

 

Thankfully for all of us – big tankers and small – the flow forces at work are universal.  

 

Interestingly, the article I linked earlier (from the Annual Review of Marine Science, Vol. 7, 2015) characterizes "wave-driven flow" and "unidirectional flow".

 

I have to read around their formula-talk, but after that the article is a great read.

 

Check out the article's summary points at the very least:

 

[PJPS]

I don’t disagree with any of it, I have 2 mp10s. If I don’t have them opposite, I can’t vary the flow to be gentler on the softy end than the acro end.  All the while having enough turbulence to wash the sticks at all times.  The NTP antisynced periods (4) are a mixture of standing waves and “gyre” flow according to ecotech.  It’s an absurd amount of water movement in my tank, it occasionally splashes out.  But because they work opposite each other, the goni and the leather aren’t blown too hard in one direction.

 

Not arguing anything, just conveying the realities I see, with my eyes, about water dynamics in this tiny box.  I’ve got it so there is always boundary layer breaking levels of water movement at all times (except aiptasia hunting time during lights out) while not upsetting the softies, LPS, or SPS in a tiny box.  I know the physics of water are pretty set in stone, the reaction of coral being hit by flow at all times in every direction (my goni flies out in all directions at once), aren’t.  The flow literally has a few inches before it hits something, there is no “open water” for flow to carry in.

 

So while interesting to read, I basically have the one option I’ve dialed in to this tank over months that delivers constant boundary layer breaking flow (which you correctly note is critical), without upsetting more than 1 ricordea that’s perpetually shrunken because it refuses to migrate from the corner of a rock.

 

 

 

 

[joshthebox]

Reefcrest anti sync has always worked very well for me. For both Acro tanks and softy ones. 

[mcarroll]

9 hours ago, PJPS said:

I don’t disagree with any of it, I have 2 mp10s.

With up to $700/40 watts worth of flow in that small amount of space – pretty much the max possible without being silly about it – there's plenty of energy being added between the two pumps that the effect I mentioned is minimized.  

 

But notice the amount of overkill you have in oder to achieve the level of flow where "interference" doesn't matter.  And to your earlier question, yes, your tank would have almost all turbulence, or wave-directed flow, and almost no unidirectional flow.  (Each has its use.)

 

Also, the effective reach on an mp10 is only about 12"...very soft past that.  So the facing pump would have to be within range for the interference effect to matter.  In a tank this size, with those pumps, it would be borderline anyway.

 

 

[mitten_reef]

There are a lot more to flow planning in a small limited space of a tank, even more so for a nano - more beyond the textbook science can apply.  our aquascape takes up a good chunk of volume, leave little room for any laminar to get around before it's turned turbulence.  Tidal flows happen twice a day, I don't think that is the "main flow" anyone can emulate in a tank environment.  if we're talking wave surges/swells, sure something can be created (watch youtube on the Long Island aquarium's surge tank, somewhere in here).  but again, space constraints are more than likely for a home setup.