Silent and Failsafe Overflow System

[jb61264]

Originally Posted by robojet

I'll try to answer this... kinda scary, since I'm just been asking questions...

It has to do with linear flow. The more linear flow the better. So, let's say your oveflow is coast to coast on a 48" tank, and you have teeth that are 1/4" and a 1/4" apart, you have reduced the linear flow to 24". A 24" sheet of water also going to be taller as it runs over the overflow, where on the same tank it would be a much thinner sheet of water if the linear flow was 48". This is suppose to be a much more efficient overflow (for reasons I am unable to explain at the moment).

So, what I've seen in some of the posts, is that people will use eggcrate to help keep critters out of the oveflow... so rather than having 1/4" teeth, you only have say 1/16" teeth...

Hope that helps.

Thanks for reminding me about that...now that you said that, I remember way back when I was building mine someone mentioned that about linear flow...I absolutely love my overflow on my 75...since my tank is 48" wide, I made my overflow box 36" wide so I could hang my returns on both corners of the tank. I went with 1" plumbing all the way around (I too thought 1.5" looked way to big on my tank) and it works perfectly. I did reduce my return flow after a T split going to each corner to 3/4" however to increase the velocity of the return flow when it enters the tank...glad I did this

[jb61264]

Originally Posted by NaClH2Opgh

You could also get an acrylic piece cut that will cover the top. Just put some small rubber stops at the corners and the middle to hold the top up enough for the box to still skimm with no teeth. Make it black acrylic and it will keep light and algae out of the box also.

You just gave me a project to do for the weekend I like this idea...have been using eggcrate and it works ok, but this sounds like a better idea...trying to figure out what to use for the rubber stops though

[NaClH2Opgh]

They sell them in the cabinet hardware section at HD or Lowes. They look like little clear rubber domes. The go around the edge of the openings so when you close a drawer or door it doesn't slam.

[robojet]

So, I finally picked up some plumbing pieces to make a final attempt at nailing down all the specs for my external overflow Yeah Right!

So, I picked up a tee, an elbow, a bulkhead (all 1"), and after I started doing some measurements, I have now gone back to an internal overflow!

Yep... full circle! The way I plan on aquascaping my tank and the difference in an internal weir (with the external overflow) vs an internal overflow with the 1" plumbing is not significant enough to make me want to do the external overflow... so, I'll post my new drawing as soon as I can get to it.

[BeanAnimal]

Originally Posted by tmerrick
I have looked thru most of this thread, but havent seen many retrofit this into a factory reef ready overflow. I have dual corner overflows, I assume I would be able to divide up these 3 components over 2 boxes and then still have 1 extra hole to duplicate a pipe? Tank height is 24".
1) Emergency standpipe
2) Siphon standpipe
3) Open channel standpipe
4) Siphon standpipe

It is a bit more complicated due to the seperate overflows. You have no way of ensuring that the ratio of water that flows between the two boxes will remain the same. The system will self adjust to an extent, but it is possible that you will have issues keeping things quiet. Each box would have to have an open channel and a siphon (a herbie in each box). You will not have the fail-safe feature of the emergency standpipe.

The open channel weirs would need to be set high enough to ensure that the siphons had a fairly significant head against them while still leaving several inches of headroom in the overflow boxes. If they system refuses to stay stable, an option to try would be to tie the siphon standpipes from each box to a single standpipe and valve (of larger diameter than the two singles. This will help ensure that the water level in both boxes stays the same (though again you will be at the mercy of the flow going into each box).

In your poposed setup. YOU MUST use the smaller of the bulkheads for the siphons and the larger for the open channels.

[madkeenreefer]

Originally Posted by madkeenreefer

I will be using a 4500gph sequence barracuda for my return, I figure that I will loose around 2500-3000 gph with the head loss and plumbing restrictions
so around 1500 will be close to what the overflows will see. quiet a bit for a 150gl tank but its what im looking for.

I hope that the hi flow will help. what do you think

[BeanAnimal]

Help with what?

[robojet]

Well, I think this is my final design

I am going with the 1" plumbing (only pushing 400gph), and holes drilled for 1" bulkheads (even though the larger bulkhead was recommended). Seems to cause to much trouble if only using 1" plumbing. So, I have in the design, my main tank, the overflow box (no teeth), and a cover for the overflow box (which has little stubs across the front to keep it from sagging (I will add a piece of glass or something on the back to hold up the back as well). My only concern was the thickness of acrylic that will be used for the overflow and how it impacts my measurements, so I simply built in enough room to accommodate 1/4"... although I feel it will likely be 3/8". The tank will be a glass rimless, with starphire front. I plan on using 3/4" plumbing for the return, and simply putting it over the top to the far right side, maybe adding a loc-line nozzle.

I think I've got everything down OK. I'm asking for a final critique.

Thanks!

[uncleof6]

You going to be able to get the elbows in the bulkheads? What if you need to get your hand inside the overflow for some reason?

Jim

[BeanAnimal]

Jim... I think he means to leave the top removable.

Robo... you don't need 1.25" for the overflow slot. .5" will be plenty. Plan on making it adjustable because at 400GPH you may be able to get away with .25" or so.

[uncleof6]

Originally Posted by BeanAnimal

Jim... I think he means to leave the top removable.

Robo... you don't need 1.25" for the overflow slot. .5" will be plenty. Plan on making it adjustable because at 400GPH you may be able to get away with .25" or so.

I was looking at the width, not the cover.... it is going to be tight in there....probably should have stated that.

Jim

[robojet]

Originally Posted by BeanAnimal

Jim... I think he means to leave the top removable.

Yes... the top was meant to be removable.

Originally Posted by BeanAnimal

Robo... you don't need 1.25" for the overflow slot. .5" will be plenty. Plan on making it adjustable because at 400GPH you may be able to get away with .25" or so.

I want the water to be 1" below the rim of the tank. Isn't that what the top of the overflow dictates plus the depth of the water passing over the overflow? I live in earthquake country, and trying to avoid the slosh and spill from minor earthquakes. Please let me know if I've misunderstood.

Originally Posted by uncleof6

I was looking at the width, not the cover.... it is going to be tight in there....probably should have stated that.

The width of 2 3/4" will provide just enough room to get the elbow in the bulkhead. Depending on the thickness of the acrylic, I may have a squeeze fit. Once the elbow is in place, I will have at least 1/2" in front of it. It's tight, but I think it will work. I could gain a little more working space if I shorten the part of the elbow that gets inserted in the bulkhead.

[robojet]

Looks like I had left out some important dimensions... the holes are 2 5/8" from the top (to hole center), same on side.

[BeanAnimal]

Yes, the height of the weir dictates the water level in the display. I was commenting on your cover, not the position of the weir. You are putting a cover on the box to help prevent small fish from entering the overflow. On a 48" wide tank with 400GPH, the water flowing over the weir will be 1/16" of an inch or less. (I don't have time to do the math). The gap between the water surface and the cover can be greatly reduced to prevent fish from enetering the box. 1.25" is way too high even for a flow 10 times what your target is

[robojet]

Originally Posted by BeanAnimal

Yes, the height of the weir dictates the water level in the display. I was commenting on your cover, not the position of the weir. You are putting a cover on the box to help prevent small fish from entering the overflow. On a 48" wide tank with 400GPH, the water flowing over the weir will be 1/16" of an inch or less. (I don't have time to do the math). The gap between the water surface and the cover can be greatly reduced to prevent fish from enetering the box. 1.25" is way too high even for a flow 10 times what your target is

OH! Got it! I hadn't considered making it a 'slit'. My intention was to attach black eggcrate across the front. Hmmm... the only thing I'm thinking is that if the Siphon and Open Channel were to get clogged and the emergency standpipe was activated, how hi would the water rise before it kicked in. I would definitely want to make sure that the emergency standpipe was about 1/4" below the level of the overflow, so that the water in the tank didn't rise... Sorry... talking this through... I was just thinking that I had to make sure the slit was big enough to account for a rise in the water... but that should never happen...

OK... redesigning the lid now! Thanks!

[BeanAnimal]

The black eggcrate will work as well. For such a low flow, it will not hurt surface skimming too much or add any appreciable noise.

[madkeenreefer]

Originally Posted by BeanAnimal

Help with what?

You asked "what flow I would be using" and I was asking you "if it would help"
I am using a hi flow not for reasons for the drain lines but for other reasons
did'nt mean to confuse things

[robojet]

Update design for the lid... no sagging issue with a piece across the front and back. 1/4" short at the front to allow for overflow. No reduction in linear flow at all. I think I like keeping the lid flush with the top of the tank - better aesthetically.

[robojet]

So, I'm now trying to figure out my sump configuration. Would the flow from the open channel be enough to feed a small refugium? My intention is to just keep some rubble rock a cheato. I will only have 400gph... trying to decide between:

1) overflow/skimmer -> refugium -> return
OR
2) overflow/skimmer -> return <- refugium

thanks!

[uncleof6]

robojet, I am thinking we hijacked this thread enough, and perhaps a discussion of sump design would go better in another sump design thread, or just make a new thread for it.

Regards,

Jim

[robojet]

Hmmm... OK. I wasn't trying to design my entire sump here, I was just hoping someone could tell me if the flow rate from the open channel was enough to feed a refugium.

That's OK... I'll figure it out.

Originally Posted by uncleof6

robojet, I am thinking we hijacked this thread enough, and perhaps a discussion of sump design would go better in another sump design thread, or just make a new thread for it.

Regards,

Jim

[uncleof6]

Originally Posted by robojet

Hmmm... OK. I wasn't trying to design my entire sump here, I was just hoping someone could tell me if the flow rate from the open channel was enough to feed a refugium.

That's OK... I'll figure it out.

Looking at the overall flow rate for your system, I am thinking that the flow through the open channel is going to be very low, just a wild guess < 50 gph, as the bulk of the flow should be through the siphon. I would have a tendency to say the is not sufficient for the fuge. Beyond that, both the siphon and open channel should be in the skimmer section.

Jim

[robojet]

Got it... and thanks so much. I think I have the overflow design complete. Next posts will probably be after I order and receive the tank.

Thanks for the help!

Originally Posted by uncleof6

Looking at the overall flow rate for your system, I am thinking that the flow through the open channel is going to be very low, just a wild guess < 50 gph, as the bulk of the flow should be through the siphon. I would have a tendency to say the is not sufficient for the fuge. Beyond that, both the siphon and open channel should be in the skimmer section.

Jim

[HOBrien]

What is the best way to do an overflow if I am unsure if the back glass is tempered or not. The tank is 10yrs old or more. Its an old DAS tank that has the filtration box inside of it. The reason I am asking is that I will be limited to the space available behind the tank when I move it into its new spot. The allowable space is 2" from tank to wall.

Any suggestions would be greatly appreciated. It is currently using a HOB overflow.

This is a 200gallon tank.

[HOBrien]

Anyone with any advice?