Calfo Style Overflow boxes

[E-A-G-L-E-S]

Well, my 58g just got drilled an i currently have a 1" bulkhead in each top corner. With an elbow and strainer on them inside tank and stockman's on outside.

These two 1" drains pull less of surface than my cpr hang on overflow did. But the cpr pulled from a good 75% of my 36"x18" surface area at ~6" wide.....so could i use two seperate boxes at 6" each and still have middle 24" open? I know it wont be as good, but much better than without them at all, right?

...By the way i am pushing ~400gph from return after head loss

Thanks for your help!

 

[BeanAnimal]

It should work, but it will be hard to balance them if water is sloshing around. With that low of a flow you should be ok though.

 

[stevedola]

drain placement for a calfo style overflow

drain placement for a calfo style overflow

I have a 90 all glass tank that is not RR. I want to drill the back and install a calfo style overflow in. I figured a 1" bulkhead (so a 1 3/4" hole) will be needed and then place the acrylic box over the drain hole.

My question is how far down does the hole go from the tank support brace?

and then where do I place the box to surround the drain? does it butt up against the brace?

would you all put a grate or mesh cover over the drain or maybe just install a "fence" of eggcrate on the acrylic box.

Ive seen many of these posts and numerous pictures but its hard to see exactly where the hole is placed. It maybe that these drains can be a number of inches below the tank edge and it wont make a difference but I dont want to drill the tank and have the water level end up too low. any help would be great.

 

[Jeremy Blaze]

<a href=showthread.php?s=&postid=9235579#post9235579 target=_blank>Originally posted</a> by E-A-G-L-E-S
Well, my 58g just got drilled an i currently have a 1" bulkhead in each top corner. With an elbow and strainer on them inside tank and stockman's on outside.

These two 1" drains pull less of surface than my cpr hang on overflow did. But the cpr pulled from a good 75% of my 36"x18" surface area at ~6" wide.....so could i use two seperate boxes at 6" each and still have middle 24" open? I know it wont be as good, but much better than without them at all, right?

...By the way i am pushing ~400gph from return after head loss

Thanks for your help!

Look at my posts that started this thread. I used 2 seperat boxes and it worked fine.

 

[steelerguy]

Is it a no no to run your closed loop from the horizontal overflow? I built an overflow that is 16" x 4" x 4", which according to the calculator on the front page of RC, exceeds the minimum to flow 1500 gph. My sump return pump and closed loop together, with head loss will probably push about 1200 gph (50 gallon tank).

I would like to put the drain for the CLS in the overflow to not only hide it, but to provide some really good surface skimming. What I don't want is a lot of noise since this will be in my living room.

What are your thoughts? Would it be too noisy?

 

[drstupid]

i asked my tank builder if i could do that, he said no. i just took his word on it from experience, but it makes sense when you think about it. the water in your overflow is replenished at the rate of the main return. i'm running mine pretty high, at about 1000 gph/8x turnover maybe. the closed loop is pushing much more than that, mine's doing about 3000 gph given the head pressure of the plumbing. you'd be sucking all the water out of the overflow before it'd get a chance to be replenished.

i suppose it'd work if your closed loop was doing less turnover than your main return, but that wouldn't make a lot of sense.

 

[drstupid]

what i just said isn't totally right, but the basic principle is. you could theoretically have enough water to both drain your main turnover (say 1000gph) and supply the closed loop (say 3000gph), but the lip into the overflow would have to be able to supply the 4000gph the pumps want to draw. you want it thin to get the surface skimming, otherwise you just end up with a larger, funny shaped tank.

 

[steelerguy]

The more I read last night the more I started to think it would not work properly. I started to imagine the overflow box having so much water going through it that the water level would have to be really high to replenish it, causing a lot of slurping and splashing.

I guess I will put the bulkhead below the box...dang...now I need to buy a ship a $2.50 bulkhead suction stainer and shipping will be 3 times that. Guess I will just have to buy more stuff to justify the cost.

 

[BeanAnimal]

<a href=showthread.php?s=&postid=9499169#post9499169 target=_blank>Originally posted</a> by drstupid
i asked my tank builder if i could do that, he said no. i just took his word on it from experience, but it makes sense when you think about it. the water in your overflow is replenished at the rate of the main return. i'm running mine pretty high, at about 1000 gph/8x turnover maybe. the closed loop is pushing much more than that, mine's doing about 3000 gph given the head pressure of the plumbing. you'd be sucking all the water out of the overflow before it'd get a chance to be replenished.

i suppose it'd work if your closed loop was doing less turnover than your main return, but that wouldn't make a lot of sense.

Heh?

3000GPH return pump and a 3000GPH closed loop pump, both fed from the overflow.

The loop pump will suck 3000GPH out and the other 3000GPH will flow to the sump. It will work just fine. You will have 6000GPH going over the weir.

 

[BeanAnimal]

So the only question is "HOW MUCH" flow can you deal with over the weir and still have acceptable surface skimming.

Of course the thinner the sheet of water, the better... but with a 16"x4" overflow will only give you 20" of linear overflow. That is rather small for the type of flow you are talking about. I prefer to to make them the length of the tank In my case that is 48". With 2300+ gph going over my weir, the water is maybe 1/16" thick.

 

[steelerguy]

I am going to install it in the middle of the back so it is actually 24" of skimming surface (16 length and 4 on each side). Still, is 24" enough to provide good surface skim AND be quite? Not sure, this is my first reef tank design.

 

[stevebla]

overflow box

overflow box

I have a overflow box 10LX4wX6H 1.5" Bulkhead I am testing it with fresh water and flow 500gph with little noise Pics in gallery

 

[cbcostanza]

Just a question. On the overflow/drain calculator, does "Recommended minimum linear overflow size" mean the perimeter of the overflow that water will be going over? Just want to make sure.
thanks

 

[loves saltwater]

I built mine and it makes no noise at all very quite overflow is 30"L X 4.5" W X 5" D plumbed with 3/4 PVC

Here is a top view of the overflow the pipe on the left is an emergency overflow if something gets stopped up in the primary drain.

 

[steelerguy]

loves saltwater, so you are only using one of the drains in your overflow? Where are you draining from to your sump?

I was originally planning on drilling 4 1" bulkheads in the overflow. 2 would drain to the sump and 2 would be tee'd together and go to the closed loop pump. What I may do is just drill 2 holes in the overflow to start with and test the closed loop. If it looks like the overflow is having problems keeping up while staying silent I'll just use those holes for the sump. If it is not having any problems, I'll hope I can add another 250 gph of drainage without problems.

 

[manderx]

I would still make the width and height enough to account for elbows in place, just in case you may need them. If you don't, and end up having a major slurping sound, you'll be upset that the weir is already in place and you now can't put in elbows.

just put the elbow on the outside then. trim the bulkhead stem to be just barely enough and run it backwards. there's no reason the box needs to be more than 1-2" front-to-back. you guys are wasting enough space as it is .

here's an example of how to run the bulkhead:
http://foresters-inc.com/mander/profile.jpg
the spacer between the box and the flange is the glass cut out from the hole i made. 1.5" bulkhead.

and here's how i ran the external plumbing to keep the waterlevel in the box above the bulkhead so it can't slurp:
http://foresters-inc.com/mander/drain.jpg



/still not convinced these full length overflows are giving the benefits you guys think they are. skimming surface water thinner and therefore clearing the surface film faster only means that the surface film has fewer attached proteins per square inch than it would if drawn off slower by a thicker layer of water. it's gonna hit equilibrium either way. i don't believe for a second that the time/rate differences we are talking about are enough to slow down adsorption. plus flow within the tank and fan placement has just as much if not more to do with it than overflow design.

 

[BeanAnimal]

manderx, I think if you do some research, you will find that you are wrong The surface skimming and air/water interface interaction has been studied many times. Our hobby is a minor use of such "technology". You will find more than you ever wanted to know if you look into wastewater treatment.

 

[manderx]

which is at a *totally* different scale. a huge pond of wastewater is just a bit different from a tank.

i don't believe for a second that the time/rate differences we are talking about are enough to slow down adsorption

 

[BeanAnimal]

The math is the same my friend But alas it does matter... I would rather err on the side of too much surface skimming than not enough.

 

[manderx]

sure, the base equations may be, but all of the numbers and goals are totally different.

in a tank, even the smallest overflow can skim the entire surface in under a minute. in a big waste pond we are talking what, hours? a square inch of surface film can only hold so much, so since we are talking about differences that we can measure in seconds in our tanks (~1/3 vs full length) you aren't getting anywhere near the surface film's capacity. while on a big pond you certainly are (and remember it's freshwater which can't hold as much). and even more importantly the pond is almost infinitely dirtier (so it loads up even faster) while our tanks are pristine in comparison. plus they are probably doing it more for aeration than anything since all that bacteria sucks o2 out like crazy, while aeration isn't a problem in any reef tank with even the slightest amount of flow.