Overflow design, what do you think?

addicte46

addicte46

New Member
Hello all!
I am running a 75 gallon fish only (for the time being) tank, with no overflow. I really want the benefit of having a wall to wall overflow box that will skim the top surface of the water, and I want to make all out of pvc pipe.
The design:
1)The vertical pipes with the large holes cut in the sides will skim the top surface of the water.
2)The water will then drop into the large chamber and fill it.
3)The smaller tube inside will act as a syphon and has a smaller tube attached to it that runs to the tank inlet. (to help restart the syphon after a power outage... water traveling across the tube will act as a vacuum, restarting the syphon)
4)Syphoned water will fill the chamber outside the tank then overflow into the drain tube.
What do you all think???
 
sweatervest13

sweatervest13

Active Member
Quote:
Originally Posted by addicte46 http:///t/395168/overflow-design-what-do-you-think#post_3517596
Hello all!
I am running a 75 gallon fish only (for the time being) tank, with no overflow. I really want the benefit of having a wall to wall overflow box that will skim the top surface of the water, and I want to make all out of pvc pipe.
The design:
1)The vertical pipes with the large holes cut in the sides will skim the top surface of the water.
2)The water will then drop into the large chamber and fill it.
3)The smaller tube inside will act as a syphon and has a smaller tube attached to it that runs to the tank inlet. (to help restart the syphon after a power outage... water traveling across the tube will act as a vacuum, restarting the syphon)
4)Syphoned water will fill the chamber outside the tank then overflow into the drain tube.
What do you all think???

IDK if this will work. The PVC with holes cut will need to be below the water line to hold the siphon, which will not skim the surface. Even if you only have it an inch or so below the water line, the surface agitation may cause the holes to suck some air and break the siphon.
Maybe I am thinking of it wrong... But that is the way I envision it working (well, not working really).
A coast to coast overflow box, is just that.. A box with teeth cut, that will skim the surface of the water, then that box will have drain holes. The return pump will pump water into the tank causing it to overflow into the box and then gravity does the rest.
In your design how does the overflow start?? How will it restart if you have a power outage? IF it does start, how will you stop the back siphon when the return pump is off so you don't overflow the sump?
Google home made overflow's and see if there is any other ideas that have worked for others.
 
mr. limpid

mr. limpid

Active Member
It looks like you a very small margin for error, you will definitely need a auto top off with that design. I never understood how the siphon overflow started up siphoning again after power outage. What size tank is this for?
 
addicte46

addicte46

New Member
IDK if this will work. The PVC with holes cut will need to be below the water line to hold the siphon, which will not skim the surface. Even if you only have it an inch or so below the water line, the surface agitation may cause the holes to suck some air and break the siphon. The PVC with the holes is not part of the siphoning... they are designed to act in the same manner as a coast to coast overflow box, skimming the surface of the water and allowing gravity to "drain" the water into the large PVC section inside the tank. The smaller tube that you see inside of the overhanging portion is what does the siphoning (sucking the water out of the large PVC section inside the tank, and into the section outside the tank
Maybe I am thinking of it wrong... But that is the way I envision it working (well, not working really).
A coast to coast overflow box, is just that.. A box with teeth cut, that will skim the surface of the water, then that box will have drain holes. The return pump will pump water into the tank causing it to overflow into the box and then gravity does the rest.
In your design how does the overflow start?? How will it restart if you have a power outage? IF it does start, how will you stop the back siphon when the return pump is off so you don't overflow the sump? The overflow starts via the smallest tube (the one attached to the small tube inside the overhanging pvc)... the smallest tube is attached to the top of the tank inlet (the return from the sump)... the returning water passing across the tube opening creates a vacuum that should start/re-start the siphon.
Google home made overflow's and see if there is any other ideas that have worked for others. I have been "google-ing" extensively, and have used all of the information I have gathered to put this together.
 
addicte46

addicte46

New Member
really the same idea as what you posted, but adding skimming the surface, and the line connecting the siphon to the tank inlet to help re-start the siphon
 
snakeblitz33

snakeblitz33

Well-Known Member
Adding the line to connect the siphon would be easy enough of an addition, but not necessary. I would suggest using an aqualifter pump as a backup just in case the siphon fails.
You also are unaware that on the back side of the overflow, you will also need an air hole drilled in the cap and modified with some tubing to adjust air flow going down the tube.
Your design will not work in it's current state. You need both bends in the front and in the back, so that when you cut off the water flow, water will stay in the pipe, and potentially keep the siphon. As your design is now, once you cut off power to the pump, water will drain directly to the sump and break the siphon every single time.
Just something I wanted to point out.
Also, just because there isn't that little horizontal PVC thing that you made on the designs that I posted, doesn't make it *not* a surface skimmer.... that's actually how overflows work. The top pipe lets surface water down into the pipe. The longer the pipe, the less bubbles end up in the siphon tube. Since the water level is determined by the level of the pipe, this pipe *is* the surface skimmer.
 
sweatervest13

sweatervest13

Active Member
I am trying to see it... I think I get the vacuuming part to start the siphon. When the return pump is on, it will push water into the tank and the little line is attached to that (return line to the tank), the rushing water will create a vacuum that should start the siphon for the little tube.. Right??
Will the siphon from that little tube be enough to get the large U tube siphon going? IDK. Maybe.
At what water level will the PVC with the holes be??
There are some real experts at tank plumbing on the site. Hopefully they will respond too.
 
snakeblitz33

snakeblitz33

Well-Known Member
by the way, in your current design, you will have to suck a *long* time on the tube to get it primed. Since you are actually priming it from water directly from the sump. If you added a second bend in the back, and one in the front to be made equal, you would only be priming it from water left over from the p-trap bend, instead of from the sump.
 
beaslbob

beaslbob

Well-Known Member
Quote:
Originally Posted by sweatervest13 http:///t/395168/overflow-design-what-do-you-think#post_3517597
IDK if this will work. The PVC with holes cut will need to be below the water line to hold the siphon, which will not skim the surface. Even if you only have it an inch or so below the water line, the surface agitation may cause the holes to suck some air and break the siphon.
Maybe I am thinking of it wrong... But that is the way I envision it working (well, not working really).
A coast to coast overflow box, is just that.. A box with teeth cut, that will skim the surface of the water, then that box will have drain holes. The return pump will pump water into the tank causing it to overflow into the box and then gravity does the rest.
In your design how does the overflow start?? How will it restart if you have a power outage? IF it does start, how will you stop the back siphon when the return pump is off so you don't overflow the sump?
Google home made overflow's and see if there is any other ideas that have worked for others.
I'm confused/worried about the external water trap of that design. Looks like air could get in.
I tested some here:
https://forums.saltwaterfish.com/t/370270/the-beaslbob-trap-s
(but can't tell if the pictures show up here at work)
My confusion/worry is traping enough water in the outside "u" tube to insure siphon is maintained during power outage and normal operation returns with the power.
my .02
 
snakeblitz33

snakeblitz33

Well-Known Member
I dont think you are understanding me.
You need the ptraps on both sides so that you can maintain siphon while the pump is off. With your current diagram, an aqualifter pump would have to pull water all the way up the pipe but by that time your tank would flood before the siphon starts. Also, you dont want a full siphon in your pipe without an open channel.
 
beaslbob

beaslbob

Well-Known Member
Quote:
Originally Posted by SnakeBlitz33 http:///t/395168/overflow-design-what-do-you-think#post_3517650
I dont think you are understanding me.
You need the ptraps on both sides so that you can maintain siphon while the pump is off. With your current diagram, an aqualifter pump would have to pull water all the way up the pipe but by that time your tank would flood before the siphon starts. Also, you dont want a full siphon in your pipe without an open channel.
It could be using a tube within a tube design to trap the water. So a 4" pipe hanging down say 3' with a 1" centered in that pipe that goes up to 2'10" from the top would trap the water under that 2'10".
but then I'm just trying to figure what the design actually is.
my confused .02
 
You must log in or register to reply here.
Top