Clip on overflow teeth?

[03LightningSVT]

Yup splitting hairs to the nth degree Happens a lot when debating the sciences Often times lab results and real world results differ vastly due to lack of controls in the real world environment. Don't know about you but I live in the real world, not a lab. Here's my final take regarding this subject:

IMHO, it depends on the water sheet thickness (flow) going over the weir. I draw the line at 3/8".

Low flow through overflow box = toothless with lid on overflow just above the thin (1/8" - 1/4" approx.) sheet of water passing over the weir, this will create a "water slot". If the "water slot" is greater than 3/8", you're going to have issues with small snails, small fish, etc. getting into the overflow box as noted in many different threads and also in replies above this post.

High flow through overflow box = teeth with lid on overflow just above the 3/8"+ sheet of water passing over the weir.

IMHO, there is a design flaw regarding the gap to tooth ratio (2:1 approx.) used on many commercially available "reef ready" tanks. This lame ratio (the gap is only twice as wide as the tooth) is a major contributing factor for causing many to promote/recommend a toothless weir design. Most high flow toothless weir users get tired of taking things out of their overflow box that don't belong there and end up placing gutter guard, eggcrate, etc at the top of the weir (adding teeth) to prevent the unwanted visitors.

IMHO, if using a high flow toothed weir, the gap to tooth ratio should be more like 4:1 (the gap for water to flow through should be at least four times as wide as the tooth itself) as long as the gap does not exceed the 3/8" noted above or sooner or later you're going to have the same issues of unwanted small visitors in the overflow box.

After all, you're in the DIY forum, open them teeth up, let the big dog eat!

 

[GroktheCube]

I have no doubt a toothless overflow is more efficient.

After running toothless for a couple years on my 120, I will be going back to a toothed design for my new build (c2c external) this summer. I've had to wrangle wrasses out of the box far too many times. Having a barrier between overflow rim running all the way up to the cover is a high priority given it will be a peninsula design and access to the box will be slightly more limited than on my 120.

Will it be as efficient as toothless? No, but a 30" overflow with .5" tooth spacing is still perfectly adequate for my needs, and I'll sleep better at night knowing I wont have fish either stuck in the box or feeding for the 4"+ carapace width Xanthid that guards my sump.

 

[sleepydoc]

Yup splitting hairs to the nth degree Happens a lot when debating the sciences Often times lab results and real world results differ vastly due to lack of controls in the real world environment. Don't know about you but I live in the real world, not a lab. Here's my final take regarding this subject:

IMHO, it depends on the water sheet thickness (flow) going over the weir. I draw the line at 3/8".

Maybe, maybe not. As I said in my post, there are assumptions and unknowns that can make the difference between splitting hairs and splitting logs. Without knowing them it's really difficult to know for sure.

Ironically, if you've got more than ⅜" going over the weir, you're probably negating the purpose of a toothless weir, theoretical or otherwise. Either your weir is too narrow, or you've got so much flow that it doesn't matter.

 

[wolfblue]

I went toothless in 1994 just because its easier to fabricate. I like it better and I wont ever go back to teeth. Never had much more than gobies go over, maybe a gramma.

 

[03LightningSVT]

Maybe, maybe not. As I said in my post, there are assumptions and unknowns that can make the difference between splitting hairs and splitting logs. Without knowing them it's really difficult to know for sure. Logic and common sense leads me to believe that proper flow throughout the entire system (sump and display) will create a near homogeneous condition of everything in the water column, including organics. Dead spots/stagnant areas/low flow areas are where you will find concentrations of organics. Logic and common sense also leads me to believe that the flow/turbulence/agitation/water movement created by power heads such Vortechs, Tunzes, wavemakers etc. easily overcome any tendency for organics to be drawn to the surface of the water. It's just plain silly to believe otherwise as one of the primary purposes of these things is to eliminate dead spots/stagnant areas/low flow areas,its it not? Surface water agitation is also a inherent direct by-product of flow enhancement devices. That's a good thing, surface water agitation improves gas exchange.

Ironically, if you've got more than ⅜" going over the weir, you're probably negating the purpose of a toothless weir, theoretical or otherwise. Either your weir is too narrow, or you've got so much flow that it doesn't matter.Proper system flow is what negates the organic removal advantage of a toothless weir for the very reasons noted above. It doesn't matter if it's 3/8" or 1.5" going over the weir, with proper system flow the water is nearly homogeneous.

Low flow system = use toothless, you need the organic removal advantage.
Teeth on a low flow system are detrimental to a healthy tank.

High flow system = use teeth or toothless, the organic removal advantage is minimized to a hair splitting difference, not logs.
Toothless on a high flow system will have you removing unwanted visitors from the overflow box.

 

[thejuggernaut]

Where is the data Calfo has? I would enjoy reading it.

 

[uncleof6]

I would hLogic and common sense leads me to believe that proper flow throughout the entire system (sump and display) will create a near homogeneous condition of everything in the water column, including organics. Dead spots/stagnant areas/low flow areas are where you will find concentrations of organics. Logic and common sense also leads me to believe that the flow/turbulence/agitation/water movement created by power heads such Vortechs, Tunzes, wavemakers etc. easily overcome any tendency for organics to be drawn to the surface of the water. It's just plain silly to believe otherwise as one of the primary purposes of these things is to eliminate dead spots/stagnant areas/low flow areas,its it not? Surface water agitation is also a inherent direct by-product of flow enhancement devices. That's a good thing, surface water agitation improves gas exchange.

Proper system flow is what negates the organic removal advantage of a toothless weir for the very reasons noted above. It doesn't matter if it's 3/8" or 1.5" going over the weir, with proper system flow the water is nearly homogeneous.


Low flow system = use toothless, you need the organic removal advantage.
Teeth on a low flow system are detrimental to a healthy tank.

High flow system = use teeth or toothless, the organic removal advantage is minimized to a hair splitting difference, not logs.
Toothless on a high flow system will have you removing unwanted visitors from the overflow box.

Your logic actually results in the organics being mixed back down into the tank, and a lower concentration of organics goes over the weir, and a lower concentration of organics is fed to the skimmer. Since the skimmer efficiency is affected by the organic concentration of the influent, the skimmer efficiency suffers.

However, I am not going to debate what is another opinion based on the common hearsay. It will just end up being circular. (It already is.)

 

[thejuggernaut]

I think with the amounts of flow we have in our tank, organic concentrations are going to be as close to homogenized as you can get. If you think about it, the water in the top left of the tank would probably make it to the bottom right of the tank in a few seconds. The water is churning so quickly, that there isn't time for nutrients to concentrate in any section of the tank, including the surface. If they did rise to the surface that quickly, we would see large amounts of proteins on the surface of the water in our sumps (all the water is drawn from below the water line once it enters the sump). I keep hearing about the "science" behind running a smooth weir, but have never seen any links to it, atleast to how it relates specifically to our high turn over, high flow reef tanks. The link to Bean's site was all anecdotal, and the only thing that specific to skimming was a comparison to a lake with an oil slick on top. While I agree with everything he said, it is like comparing apples and hand grenades. Take that same pond, churn it up to 80X per hour and continually recirculate the water, and I bet that oil won't have time to settle back to the top. I think the reason I haven't seen any science behind it is because there isn't any that relates to our situation.

All that said, I still prefer a smooth weir. Mainly for 3 reasons.

1. The running water level is much closer to the power off water level. Meaning I will have less water drain to the sump when the return pump is off. That way I can either run a smaller sump, more water in my sump, or a larger top off reservoir.

2. At a given length and flow, a smooth weir will be quieter than a toothed one. The water will usually stick to the walls of the overflow and not make any noise at all.

3. Finally, and the real reason I run a smooth weir. It is ALLOT easier to clean. With a 40" weir you are looking at around 45 teeth in a standard setup. That would take 15 minutes with a tooth brush to clean 2-3 times a month. It takes me 10 seconds with a magic eraser to clean a smooth weir.

If their is some science out there then show it to me. But I doubt there really is, atleast in our specific situation.

 

[thejuggernaut]

However, I am not going to debate what is another opinion based on the common hearsay. It will just end up being circular. (It already is.)

So, inject an opinion that has nothing to do with the OP's question, then when someone questions it, don't provide any literature to back up your "scientific" answer. Then accuse them of not being worth of debate on the subject because their argument is hearsay? This argument is brought up almost daily, but I never see anything closely relating to data on the subject. Just hearsay.

 

[03LightningSVT]

Your logic actually results in the organics being mixed back down into the tank, my logic has organics mixed evenly (homogeneous) throughout the entire system and a lower concentration of organics goes over the weir there are no concentrations of anything with a homogeneous water column , and a lower concentration of organics is fed to the skimmer. there are no concentrations of anything with a homogeneous water column Since the skimmer efficiency is affected by the organic concentration of the influent, the skimmer efficiency suffers. there are no concentrations of anything with a homogeneous water column. Geez, I feel like a broken record. The ability of a high flow system to have a homogeneous water column must be a concept that some can't grasp.

However, I am not going to debate thank you what is another opinion based on the common hearsay call it what you like, I call it logic and common sense. It will just end up being circular. (It already is.) QUOTE]

 

[RocketEngineer]

The problem with the homogeneous water column hypothesis is that it does not exist. EVER. The proteins and oils will always be at higher concentrations on the surface of the tank. ALWAYS. Even if it is only 1% higher, it is still a higher concentration at the surface than below the surface. Therefore, pulling water from the surface will ALWAYS be more effective at removing these from the display compared to removing water from under the surface.

Have you ever looked at a raging river and seen foam collecting in the calm centers of the whirlpools? No matter how fast the water is moving, the oils are always trying to float and the flotation force will often overcome the downward surface tension force of the moving water.

The physics dictate that a homogeneous water column will never occur. And because of that, pulling water from the surface will ALWAYS be more effective at removing proteins from a given volume of water than pulling water from below the surface.

And that, is the entire point of the argument.

Now, what can occur is you reach an equilibrium within the system such that the amount of proteins being released into the display by the inhabitants is being removed at the same rate by the filtration systems (biologicals, skimmer, GAC, ex.). Because the overflow is removing some percentage of the proteins present in the display per minute (no matter how poorly its design) and the skimmer is removing about 30% of those that pass through it, you can reach a state of equilibrium within the entire setup. Nobody is arguing that this can’t occur. In point of fact, quite often it does occur. But this is not the same argument as the most effective overflow design.

 

[03LightningSVT]

The problem with the homogeneous water column hypothesis is that it does not exist. EVER. The proteins and oils will always be at higher concentrations on the surface of the tank. ALWAYS. Even if it is only 1% higher, it is still a higher concentration at the surface than below the surface. Therefore, pulling water from the surface will ALWAYS be more effective at removing these from the display compared to removing water from under the surface. SPLITTING HAIRS

Have you ever looked at a raging river and seen foam collecting in the calm centers of the whirlpools? No matter how fast the water is moving, the oils are always trying to float and the flotation force will often overcome the downward surface tension force of the moving water. Yup they collect in the calm no doubt about that. Ever see a child's helium ballon in a typhoon/hurricane/tornado?

The physics dictate that a homogeneous water column will never occur. And because of that, pulling water from the surface will ALWAYS be more effective at removing proteins from a given volume of water than pulling water from below the surface. SPLITTING HAIRS

And that, is the entire point of the argument. I consider it a discussion/debate

Now, what can occur is you reach an equilibrium within the system such that the amount of proteins being released into the display by the inhabitants is being removed at the same rate by the filtration systems (biologicals, skimmer, GAC, ex.). Because the overflow is removing some percentage of the proteins present in the display per minute (no matter how poorly its design) and the skimmer is removing about 30% of those that pass through it, you can reach a state of equilibrium within the entire setup. Nobody is arguing that this can’t occur. In point of fact, quite often it does occur. But this is not the same argument as the most effective overflow design. Equilibrium mentioned in post #18. uncleof6 nailed it...circles

 

[thejuggernaut]

The reason it keeps running in circles is because there is no definitive answer because even if there is a difference, it is so small that it is beyond any normal means of measurement. That is kind of my point. Making claims that it is an inferior system or that it is a backwards step and is detrimental, is completely over exaggerated. To many, loosing an un-measureable bit of performance in order to keep your $150 jaw fish out of your filtersock is worth it, and completely understandable. Either way, I think teeth are a pain to clean, so I'll stick to smooth weir. I may feel different if I ever loose a fish down my overflow though.

I may have come off a little hostile last night, and I don't have any science to back my claim, but neither does anyone else. Even the people who passionately defend their opinion/position.

 

[GroktheCube]

Teeth are definitely a PITA to clean. That vs having fish end up in my overflow/sump is what I weigh.

 

[Jay_R]

I have a weir comb, same as the one identified earlier;

http://www.coralculture.co.uk/shop/index.php?cPath=157_229

It's a great piece of kit. The teeth pull out for easy cleaning, and it keeps fish and snails out of my weir.

Although I have a hawk fish that does enjoy a dip in the weir, so an outlet strainer on my durso drain is an added element of protection;

http://www.fishfurfeather.com/aqua-medic-outlet-strainer-40mm-p-4163.html

I certainly wouldn't go without the weir comb now, and would recommend one all day long for the price and ease of installation. Further, the weir comb does a good job of collecting any hair algae that i miss when cleaning up. Happy days.