can i do this? bulkhead

perenes · 06/17/2009, 12:53 PM

can i instal a bulkhead like this

red= bulkhead
light green= pvc

perenes · 06/17/2009, 12:55 PM

i plan on drilling about 2 inches down from the bottom of the black trim
and then running a pvc 90 then a straight pipe to the top

can this work?

der_wille_zur_macht · 06/17/2009, 01:54 PM

It'll work, but it'll be noisy.

You are better off designing a traditional overflow box around the hole, then using a Durso-style standpipe in it. You can still do this with a hole through the back of the tank, it just means the plumbing on the Durso is a bit different.

Another option is an overflow kit from glass-holes.com - it's a very foolproof solution.

perenes · 06/17/2009, 02:00 PM

is there any ways you can eliminate the noise?

der_wille_zur_macht · 06/17/2009, 02:51 PM

Build an overflow box around it, and use a conventional standpipe design.

The problem with using an upturned elbow or strainer like that is that you're asking a single thing to do two functions. The functions are:

1) Keep the water level in the display tank constant
2) Drain the "correct" amount of water to the sump

#1 is self explanitory. We don't want to drain the entire display tank, we want the level in it to be constant. If you use an upturned elbow, the water level will sit right around the opening of the elbow. If you use an overflow box, the lip of the box (sometimes called the weir) sets the water level in the tank.

#2 is a little harder to explain. When water is draining through a pipe purely by gravity, there is a maximum amount of flow a given pipe can handle. By nature, if you keep the opening of that pipe under water, it'll flow that much.

However, we don't want to hit the maximum flow, because then there's zero margin for error or adjustment. Instead, we want the water draining out of the tank to equal the water we are pumping into the tank (via the return pump in your sump.) However, that pesky drain pipe wants to have a certain amount of flow.

To get everything to work out, we allow the drain pipe to suck some air. This lets it self-regulate - it'll suck water up to the point that it is matching the volume pumped by the return pump, and it will naturally "use up" all extra capacity by sucking air. This is the magic of a well designed standpipe. It's totally self regulating and requires no adjustments.

The problem is, if you suck this mix of air and water in through a single opening (i.e. your upturned elbow) it gets very noisy. This noise is nearly impossible to control with a single opening like that. This is why most good standpipes use a very small "vent" opening, and keep the water intake submerged below water level. The water intake sucks in water, and the vent intake sucks in air. They mix inside the pipe, instead of right at the opening, so it's much more quiet.

This brings us back to your idea of using an elbow with no overflow box around it. If you try to do this, you are asking the opening of the elbow to set the water level AND regulate flow (by sucking in both air and water). Without the overflow box around it to set water level, there is no way to separate air and water intake, which means it'll never be quiet. If you were to try to use a durso-style fitting on your elbow (i.e. separating the air and water intakes), you'd lose control over water level, and your display tank would overflow. Hence, you need the overflow box there to set the water level so that you can use a quiet standpipe design without relying on the standpipe to set water level, too.

Whys · 06/17/2009, 03:06 PM

+1 on glass-holes.com

+1 to der_wille, cuz his answer rocksaur.

perenes · 06/17/2009, 03:42 PM

what if you put a hose in the middle to let the air escape
?

perenes · 06/17/2009, 03:43 PM

or take up the extra space

Whys · 06/17/2009, 03:56 PM

Perenes, I don't know if anyone can give you a more complete answer than already given. So perhaps I should ask...

Why are you opposed to using an actual overflow box?

jayelblock · 06/17/2009, 05:12 PM

Thanks der wille. I knew what to do, but now I know why--no need to reinvent the wheel. I love these moments...

perenes · 06/17/2009, 10:19 PM

i hate the space they take up in small tanks thats all

Whys · 06/17/2009, 10:58 PM

How small of a tank? Just a drain opening might not provide sufficient surface skimming. That's part of the reason overflow boxes use all that area.

Here's a thought, use a larger sized PVC end cap over the opening so that the cap edge can be under the water line and still allow water to flow between it and the elbow to the opening inside. You could hold the cap at the right height any number of ways, but you get the idea.

I can't speak for flow rate, but it might not look so bad with black PVC from Savko.

06/17/2009, 01:54 PM	#3
der_wille_zur_macht Team RC Member Join Date: Sep 2003 Location: NY Posts: 17,749	It'll work, but it'll be noisy. You are better off designing a traditional overflow box around the hole, then using a Durso-style standpipe in it. You can still do this with a hole through the back of the tank, it just means the plumbing on the Durso is a bit different. Another option is an overflow kit from glass-holes.com - it's a very foolproof solution. __________________ Inconveniencing marine life since 1992 "It is my personal belief that reef aquaria should be thriving communities of biodiversity, representative of their wild counterparts, and not merely collections of pretty specimens growing on tidy clean rock shelves covered in purple coralline algae." (Eric Borneman)

06/17/2009, 02:51 PM	#5
der_wille_zur_macht Team RC Member Join Date: Sep 2003 Location: NY Posts: 17,749	Build an overflow box around it, and use a conventional standpipe design. The problem with using an upturned elbow or strainer like that is that you're asking a single thing to do two functions. The functions are: 1) Keep the water level in the display tank constant 2) Drain the "correct" amount of water to the sump #1 is self explanitory. We don't want to drain the entire display tank, we want the level in it to be constant. If you use an upturned elbow, the water level will sit right around the opening of the elbow. If you use an overflow box, the lip of the box (sometimes called the weir) sets the water level in the tank. #2 is a little harder to explain. When water is draining through a pipe purely by gravity, there is a maximum amount of flow a given pipe can handle. By nature, if you keep the opening of that pipe under water, it'll flow that much. However, we don't want to hit the maximum flow, because then there's zero margin for error or adjustment. Instead, we want the water draining out of the tank to equal the water we are pumping into the tank (via the return pump in your sump.) However, that pesky drain pipe wants to have a certain amount of flow. To get everything to work out, we allow the drain pipe to suck some air. This lets it self-regulate - it'll suck water up to the point that it is matching the volume pumped by the return pump, and it will naturally "use up" all extra capacity by sucking air. This is the magic of a well designed standpipe. It's totally self regulating and requires no adjustments. The problem is, if you suck this mix of air and water in through a single opening (i.e. your upturned elbow) it gets very noisy. This noise is nearly impossible to control with a single opening like that. This is why most good standpipes use a very small "vent" opening, and keep the water intake submerged below water level. The water intake sucks in water, and the vent intake sucks in air. They mix inside the pipe, instead of right at the opening, so it's much more quiet. This brings us back to your idea of using an elbow with no overflow box around it. If you try to do this, you are asking the opening of the elbow to set the water level AND regulate flow (by sucking in both air and water). Without the overflow box around it to set water level, there is no way to separate air and water intake, which means it'll never be quiet. If you were to try to use a durso-style fitting on your elbow (i.e. separating the air and water intakes), you'd lose control over water level, and your display tank would overflow. Hence, you need the overflow box there to set the water level so that you can use a quiet standpipe design without relying on the standpipe to set water level, too. __________________ Inconveniencing marine life since 1992 "It is my personal belief that reef aquaria should be thriving communities of biodiversity, representative of their wild counterparts, and not merely collections of pretty specimens growing on tidy clean rock shelves covered in purple coralline algae." (Eric Borneman)

06/17/2009, 12:53 PM	#1
perenes Moved On Join Date: Mar 2007 Location: Grove city Posts: 268	can i do this? bulkhead can i instal a bulkhead like this red= bulkhead light green= pvc

06/17/2009, 12:55 PM	#2
perenes Moved On Join Date: Mar 2007 Location: Grove city Posts: 268	i plan on drilling about 2 inches down from the bottom of the black trim and then running a pvc 90 then a straight pipe to the top can this work?

06/17/2009, 02:00 PM	#4
perenes Moved On Join Date: Mar 2007 Location: Grove city Posts: 268	is there any ways you can eliminate the noise?

06/17/2009, 03:06 PM	#6
Whys Moved On Join Date: Mar 2008 Location: Spokane, WA Posts: 3,263	+1 on glass-holes.com +1 to der_wille, cuz his answer rocksaur.

06/17/2009, 03:42 PM	#7
perenes Moved On Join Date: Mar 2007 Location: Grove city Posts: 268	what if you put a hose in the middle to let the air escape ?

06/17/2009, 03:43 PM	#8
perenes Moved On Join Date: Mar 2007 Location: Grove city Posts: 268	or take up the extra space

06/17/2009, 03:56 PM	#9
Whys Moved On Join Date: Mar 2008 Location: Spokane, WA Posts: 3,263	Perenes, I don't know if anyone can give you a more complete answer than already given. So perhaps I should ask... Why are you opposed to using an actual overflow box?

06/17/2009, 05:12 PM	#10
jayelblock Registered Member Join Date: May 2009 Location: tulsa Posts: 408	Thanks der wille. I knew what to do, but now I know why--no need to reinvent the wheel. I love these moments...

06/17/2009, 10:19 PM	#11
perenes Moved On Join Date: Mar 2007 Location: Grove city Posts: 268	i hate the space they take up in small tanks thats all

06/17/2009, 10:58 PM	#12
Whys Moved On Join Date: Mar 2008 Location: Spokane, WA Posts: 3,263	How small of a tank? Just a drain opening might not provide sufficient surface skimming. That's part of the reason overflow boxes use all that area. Here's a thought, use a larger sized PVC end cap over the opening so that the cap edge can be under the water line and still allow water to flow between it and the elbow to the opening inside. You could hold the cap at the right height any number of ways, but you get the idea. I can't speak for flow rate, but it might not look so bad with black PVC from Savko.