Difference between 1.5" and 2" drain in overflow

[christyf5]

Originally Posted by sphelps

Well either way you should be using a 2" standpipe to match your 1.5" drain. You could always use 2" ABS which may be easier to find in your area, it also typically comes in 4 foot lengths.

Oh I always thought ABS was bad?

[sphelps]

Originally Posted by christyf5

Oh I always thought ABS was bad?

No, that's a common myth. ABS is completely potable and safe for aquariums. ABS is used in drains because it has a higher resistance to chemicals. Also most of the plastic parts already in your aquarium like pumps and magnet cleaners are made from ABS.

[christyf5]

Oh! Well thats great info!

So I'm at a bit of a loss with the photo you posted of the single herbie. Why does it have 1.25" pipe in it? Does the 1.25" pipe go all the way through, how is it affixed in the 2" pipe? And whats going on with the gate valve?

Sorry for all the questions, apparently I need more caffeine

[sphelps]

Originally Posted by christyf5

So I'm at a bit of a loss with the photo you posted of the single herbie. Why does it have 1.25" pipe in it? Does the 1.25" pipe go all the way through, how is it affixed in the 2" pipe? And whats going on with the gate valve?

The 1.25" pipe goes all the way through (it's one piece) and acts as the secondary or back up drain. It's supported inside the 2" pipe by the bushing.

The primary drain is created by the 2" pipe. Water flows in between the 2" and 1.25" pipe and then through the gate valve. The gate valve is used to match the flow rate to the return pump and adjust the water level in the overflow box to just below the top of the 1.25" pipe. It's just like a standard herbie but the back up drain is inside the primary.

Make sense?

[christyf5]

Originally Posted by sphelps

The 1.25" pipe goes all the way through (it's one piece) and acts as the secondary or back up drain. It's supported inside the 2" pipe by the bushing.

The primary drain is created by the 2" pipe. Water flows in between the 2" and 1.25" pipe and then through the gate valve. The gate valve is used to match the flow rate to the return pump and adjust the water level in the overflow box to just below the top of the 1.25" pipe. It's just like a standard herbie but the back up drain is inside the primary.

Make sense?

Yep we use something like that in our tanks at work (DFO), only the "inner pipe doesn't go all the way through, it sits in the bushing and has a hole in it at the level we want the tank at, reducing the flow. To flush the tank we pull up on the inner pipe and the flow is increased dramatically and sucks out all the detritus.

Cool, thats definitely something to investigate further. Thanks for the info!!

[Reefer Rob]

What an ingenious little bit of plumbing! I have 2 holes in each overflow, so I don't need it personally, but I think a link to that should almost be a sticky somewhere.

One thing I was thinking. What about eliminating the 2" standpipe inside the overflow. This should increase the flow potential and reduce detritus buildup in the overflow... just a thought.

[mark]

sphelps,

any idea of the max gph?

[sphelps]

Originally Posted by mark

sphelps,

any idea of the max gph?

The cross sectional area between the 2" and the 1.25" pipe is very close to the area of a 1.25" pipe. So both the primary and secondary should each be capable of flowing what is typical for a 1.25" drain.

[sphelps]

Originally Posted by Reefer Rob

What about eliminating the 2" standpipe inside the overflow. This should increase the flow potential and reduce detritus buildup in the overflow... just a thought.

If you did this then the full overflow box would drain when the flow is shut off, not always a good thing unless you have the sump volume, but an option for sure.

[StirCrazy]

Originally Posted by christyf5

Oh I always thought ABS was bad?

Christy, we went throught this 10 years ago......

Steve