effectiveness of small volume refugiums

[andykee]

does anyone have experience with a low volume refugium (i'm think 5.5g at the moment). i am designing a 20g (display) tank and am working on the plumbing setup, etc. i haven't really done much in terms of fuges before, so i really don't know how effective a small fuge is.

 

is there anything i should to to add to its effectiveness? chaeto only? cateo and ls? chaeto, ls, and lr? the goal of the fuge will be purely nutrient export - i have no desire to keep any special inhabitants in the fuge.

 

 

also, what is the ideal flow rate through a fuge?

[Mr. Fosi]

Whoa! Lots of questions!

 

... so i really don't know how effective a small fuge is.

 

I imagine it can be very effective. My cheato does a great job just sitting in my tank and I imagine that it would do better under better lighting.

 

is there anything i should to to add to its effectiveness?

 

I have heard good things about miracle mud. I know a lot of people add them but I have never heard anything definitive about the effectiveness of LR and/or LS.

 

also, what is the ideal flow rate through a fuge?

 

I have always advocated high light and high flow for maximum cheato growth. Low flow is good for pods, but transport in/out of aquatic cells increases as you decrease the boundary layer around them. The only ways to decrease the boundary layer is to increase velocity and turbulence.

[yardboy]

I've got full flow through the refugium on Ghetto Beauty, but then it's only about 50gph. Most of my turnover is with a closed loop. Total water volume is only about 4 gallons.

[dtfleming]

I think a 5.5 fuge is fine andy, Im working on a 10gal fuge for a 20L prop tank. this is my plan flow from tank into fuge with HOB or in tank skimmer, overflow and underflow baffles to fuge area. Fuge of LS-approx 3-4" deep, with LR and macro algae. next two more baffles to return pump up to a SCWD with two returns on both sides of the tank.

[ProFlatlander15]

I used to have a 5gal fuge on my 10gal. Aside from being able to keep the heater and return pump in the fuge and out of the display, I think any size fuge woul help. Pretty much anything capable of growing chaeto in is worth doing, IMO.

 

Edit: I don't even have sand in my fuge, I found that too much debris settled on it, so I gradually siphoned it out and now I don't have patches of gray organis material all over. LR rubble and chaeto is where it's at.

[lowball]

People seem to like using ac70s for fuges for chaeto and they certainly arent 5.5gallons. I would think it would be plenty big for macro. However, i'm a noob so take it for what its worth.

[andykee]

thanks for the responses everyone!

 

The only ways to decrease the boundary layer is to increase velocity and turbulence.

 

i don't want to split hairs with you here, but my understanding of the boundary layer (from a purely aerodynamic point of view) is that the boundary layer thickness actually increases in turbulent flow.

 

first, it is necessary to define the reynold's number - basically it is a dimensionless number used to characterize fluid flows. the reynolds number is given by:

 

Re_x = (rho * V * x) / mu

 

for the purposes of this discussion, let's assume a constant fluid density (rho) and mu is already a constant (absolute viscosity coefficient). x is used to get a "localized" reynolds number - it is the distance from the leading edge (or surface) of a body in the flow. we will also assume that the free stream velocity profile is constant. taking this in to account, we can assume that the reynolds number varies directly with flow velocity.

 

the boundary layer thickness for laminar flow is given by the following equation:

 

delta_laminar = (5.2 * x)/(Re_x^0.5)

 

the boundary layer thickness for turbulent flow is given by the following equation:

 

delta_turbulent = (0.37 * x)/(Re_x^0.2)

 

again, assuming that the reynolds number varies directly with V, the previous equations can be expressed as:

 

delta_laminar = (5.2 * x)/(V^0.5)

delta_turbulent = (0.37 * x)/(V^0.2)

 

this result shows that the laminar boundary layer grows approximately as x^(1/2) while the turbulent boundary layer grows as x^(4/5). as a result, turbulent boundary layers grow faster and are thicker than laminar boundary layers.

[r20crazy]

wow andy, didn't know you had that in you.

[andykee]

wow andy, didn't know you had that in you.

all in a day's work for an aerospace engineer

[JavaJacketOC]

thanks for the responses everyone!

i don't want to split hairs with you here, but my understanding of the boundary layer (from a purely aerodynamic point of view) is that the boundary layer thickness actually increases in turbulent flow.

 

first, it is necessary to define the reynold's number - basically it is a dimensionless number used to characterize fluid flows. the reynolds number is given by:

 

Re_x = (rho * V * x) / mu

 

for the purposes of this discussion, let's assume a constant fluid density (rho) and mu is already a constant (absolute viscosity coefficient). x is used to get a "localized" reynolds number - it is the distance from the leading edge (or surface) of a body in the flow. we will also assume that the free stream velocity profile is constant. taking this in to account, we can assume that the reynolds number varies directly with flow velocity.

 

the boundary layer thickness for laminar flow is given by the following equation:

 

delta_laminar = (5.2 * x)/(Re_x^0.5)

 

the boundary layer thickness for turbulent flow is given by the following equation:

 

delta_turbulent = (0.37 * x)/(Re_x^0.2)

 

again, assuming that the reynolds number varies directly with V, the previous equations can be expressed as:

 

delta_laminar = (5.2 * x)/(V^0.5)

delta_turbulent = (0.37 * x)/(V^0.2)

 

this result shows that the laminar boundary layer grows approximately as x^(1/2) while the turbulent boundary layer grows as x^(4/5). as a result, turbulent boundary layers grow faster and are thicker than laminar boundary layers.

 

 

HHUUUUHHHHH

[andykee]

HHUUUUHHHHH

the boundary layer is a phenomenon due to the viscous effects of a fluid moving over a body

 

on the surface of the body, the flow stagnates (i.e. it does not move). as you move further away from the body, the flow velocity approaches the free stream flow velocity. the boundary layer is thicker in turbulent flow than it is in laminar (smooth) flow. the following image should help illustrate the boundary layer.

 

[Greenstar]

Andy Kee = Original Gangstar

[clifford513]

Is Andy showing off again? (We're so proud of him )

 

[ebin]

would not any refugium be benificial? even if it was real small?

 

 

xoxo

[andykee]

would not any refugium be benificial? even if it was real small?

xoxo

i dunno - that's why i'm asking!

[Sushi]

As long as your Chaeto grows, your fuge is doing what it needs to be doing. Simple as that...

[Mr. Fosi]

I'm gonna go with you one andy. My understanding of the boundry layer only comes from a couple articles I read that talked about it with regard to water flowing over benthic systems.

 

I wonder where I got that turbulence bit from?

 

In any case, increased velocity may lead to more efficient nutrient uptake. Purely conjecture, of course, since I don't think anyone has looked at this in chaeto. Pluse, even if it were the case, there is no certainty that you would see a real-world effect.

[coral_addict]

thanks for the responses everyone!

i don't want to split hairs with you here, but my understanding of the boundary layer (from a purely aerodynamic point of view) is that the boundary layer thickness actually increases in turbulent flow.

 

first, it is necessary to define the reynold's number - basically it is a dimensionless number used to characterize fluid flows. the reynolds number is given by:

 

Re_x = (rho * V * x) / mu

 

for the purposes of this discussion, let's assume a constant fluid density (rho) and mu is already a constant (absolute viscosity coefficient). x is used to get a "localized" reynolds number - it is the distance from the leading edge (or surface) of a body in the flow. we will also assume that the free stream velocity profile is constant. taking this in to account, we can assume that the reynolds number varies directly with flow velocity.

 

the boundary layer thickness for laminar flow is given by the following equation:

 

delta_laminar = (5.2 * x)/(Re_x^0.5)

 

the boundary layer thickness for turbulent flow is given by the following equation:

 

delta_turbulent = (0.37 * x)/(Re_x^0.2)

 

again, assuming that the reynolds number varies directly with V, the previous equations can be expressed as:

 

delta_laminar = (5.2 * x)/(V^0.5)

delta_turbulent = (0.37 * x)/(V^0.2)

 

this result shows that the laminar boundary layer grows approximately as x^(1/2) while the turbulent boundary layer grows as x^(4/5). as a result, turbulent boundary layers grow faster and are thicker than laminar boundary layers.

 

 

WTF? My brain hurts now. Here's some simple math. 5G is 25% of 20Gallon. Most people sump are about that percentage and you can hold a heck of a lot of Chaeto in 5G volume of water so the quick answer is that it should be plenty effective. If your friends don't know what the heck Chaeto is, just tell them you're growing Salt Water Weed. They will dig it.

[reefitis]

If your friends don't know what the heck Chaeto is, just tell them you're growing Salt Water Weed. They will dig it.

 

-effin' awesome!

[neanderthalman]

WTF? My brain hurts now. Here's some simple math. 5G is 25% of 20Gallon. Most people sump are about that percentage and you can hold a heck of a lot of Chaeto in 5G volume of water so the quick answer is that it should be plenty effective. If your friends don't know what the heck Chaeto is, just tell them you're growing Salt Water Weed. They will dig it.

 

Umm....hate to break it to ya, but what andy posted was simple math. You know. Polynomials. Grade Nine.

[zenassassin]

Umm....hate to break it to ya, but what andy posted was simple math. You know. Polynomials. Grade Nine.

 

Grade Nine in Star Trek if you're Wesley Crusher maybe. Not on planet Earth in the western hemisphere.

[andykee]

Grade Nine in Star Trek if you're Wesley Crusher maybe. Not on planet Earth in the western hemisphere.

yeah, polynomials were covered in high school math for sure. probably even some "upper-level" middle school math. perhaps my use of greek symbols threw you off.

[epicfish]

GEEK symbols.

[clifford513]

GEEK symbols.

No, that's effin awesome

[filefish949]

yeah, polynomials were covered in high school math for sure. probably even some "upper-level" middle school math. perhaps my use of greek symbols threw you off.

 

 

my 2 year old knows Pi