Jacob’s Blog

Herbie Overflow
Funny name for a nifty idea. A guy by the name of Herbie came up with this, not that it’s an earth shattering idea but he was the first to document it and become recognized for the idea. Today I completed the addition of a Herbie Overflow to Project 360. Before I get into the install, let’s review why we use standpipes and look at a few different standpipe/overflow designs.

Why Use a Standpipe
Why we use them is fairly straightforward: In aquariums with sumps, water has to flow from the aquarium, down to the sump and eventually back to the aquarium via the return pump. All of this flowing water can cause quite a racket! Standpipes serve to quiet the water noise, to increase flow, and/or to reduce the chance of a flood (also see follow up). How we implement them is not quite as simple. Here are several of the more popular designs.

• Open Standpipe: A simple pipe connected to a bulkhead in the overflow chamber. Water in the overflow chamber rises to the height of the pipe before it can flow down to the sump. All standpipe designs share this trait, however the following designs improve on it substantially.




• Durso: A very popular design that uses a downward facing elbow at the top of the standpipe to prevent gurgling that occurs in an open pipe. The standpipe is aspirated by either drilling a small hole above the water line, or preferably using a small air valve to regulate the air flow into the standpipe.This standpipe operates best at partial siphon. The air flow is restricted to the point that siphon forces begin to take effect and pull more water down, however it’s not a true siphon as the pipe is open to atmosphere.




• Stockman: A variation of the Durso design. A sliding, downward facing bushing determines the water level. Water enters through holes drilled directly into the standpipe. The standpipe is aspirated by means similar to the Durso. The benefits of Stockman vs. Durso are debatable, however the Stockman is generally somewhat more compact comapred to Durso.




• Herbie: The Herbie design is actually a combination of designs. Two standpipes are required. One of them is typically a Durso or Stockman; this is the pipe that dictates the water level in the overflow chamber just as it would in a single stand pipe situation. The second standpipe (referred to as siphon pipe from here forward) is generally an open pipe that is lower than the inlet of the Durso pipe. Both standpipes return to the sump via separate piping, tying them together defeats the purpose. The siphon pipe must have a valve between it and the sump at some point, this is optional for the Durso pipe. The siphon pipe should be sized to handle all of the pump flow with the valve wide open, but you will run it with the valve partially closed to only allow about 95% of the pump flow. With the siphon pipe restricted to about 95% of the pump flow the water level in the overflow box rises to the Durso pipe at which point it begins to flow down both pipes. The siphon pipe is now under full siphon because it is completely submerged. A pipe under full siphon is dramatically more quiet than a pipe with air entrained in it - and the sump is very quiet as well since there is no bubbling effect. The result is a very quiet system, and an added level of protection against flooding. Ideally both standpipes should be capable of taking the full pump flow if the other. Unless the Durso/Stockman pipe becomes completely blocked it is virtually impossible to flood.




• Silent-Fail Safe: This is a modification of the Herbie method. To summarize; an emergency overflow pipe is utilized. The emergency overflow is not normally submerged or exposed to the water at its normal operating level, so in theory it is very unlikely to become blocked. If there is a failure of the other two pipes the emergency pipe handles the full pump flow and prevents a flood. Go to Bean Animal’s site and read all about it

Here are a few pictures of the above mentioned designs; the Durso and Stockman images are borrowed from http://www.randystacye.com where kits can be purchased to build your own. The Image of the Silent-Failsafe is borrowed from http://www.beananimal.com.

Durso

Stockman

Herbie

Silent-Fail Safe

The Install
So, there are at least 5 options out there, ranging from 1 to 3 standpipes. As I mentioned I used the Herbie design with 2 standpipes. I’m comfortable with two overflows, and I didn’t have room for the third pipe, so this made sense. Below are a couple of pictures of the install. What a difference this made in the noise level. Now only a trickle of water can be heard from the water entering the overflow chamber.

Plumbing:

The overflow pipes are the middle and left. The middle is the new line I added today, it’s the siphon line. The right is the return line from my pump.

Overflow Compartment:

Above you can just make out the submerged siphon line in the center of the overflow compartment. To the left is the Durso and the return pump piping is to the right.