Overflow Completely Silent – but what’s my Risk?

[ZenAle]

Fellow Reefers:

I am relatively new to the hobby and attempting to setup a 92g aquarium in my living room. My 45g sump is located in the basement, and I finally finished plumbing everything up and just have RODI water running through the system. The aquarium came with a MegaFlow Durso but I noticed it’s very noisy no matter what I do. I’ve tried all the tricks I could find (varying heights, air vent w/wo tubing, etc) but most of the noise seems to be coming from air in the drain line after the bulkhead and before the sump.

Given that my aquarium is “reef ready”, it came predrilled with 1” drain and ¾ return holes. I’ve done a lot of research, and figured I would quickly simulate the Herbie method by creating a full syphon by closing the hole in my durso cap and tuning my drain line to match the return. To my great surprise, it became completely dead silent to the point where I can’t even tell its running. Awesome!

Based on the research I’ve done, it seems that the biggest concern with the Herbie is that if the drain line should become blocked, the water in the display tank might overflow. To reduce and/or eliminate this risk, the suggestion is to add an emergency drain line that would take over if needed. However based on my current setup, I cannot figure out why I need to install the emergency drain. I must be missing something so I figured I would ask the community first.

The return pump in my sump is in the very last chamber (size = 6”x10”x12”) which means in only contains about 3.1 gallons of water in that section (water volume is kept at a relatively consistent level via Tunze Auto Top-Off and I will add a Neptune Apex controller at some point as a backup safety net). If the drain line from my main display tank clogged for whatever reason, the most water that could ever be pumped back up to my display tank would be 3.1 gallons which isn’t enough to cause an overflow. The return pump wouldn’t have access to more than 3.1 gallons because the only way the pump would get more water is if the drain was supplying it (which it isn’t because we’re saying is clogged). To test this, I closed the ball valve completely on my drain line (simulating a clog) and as expected only minimal water was added to my display tank until I could hear my return pump in the basement running dry.

What am I missing? At this point I don’t see benefit of messing with my existing plumbing to add an emergency drain. Much appreciated for your time and any feedback you care to offer.

[Breadman03]

In addition to the worst case scenario of a flood, or the pump catching fire because it runs dry while you're out, the system won't stay perfectly balanced. You will find that your water level will vary as pumps and drains get dirty and cleaned. The "emergency" drain in a Herbie functions as a constant flow balancer, allowing for small flow changes to be absorbed by the system without impacting performance or requiring user intervention.

I recommend installing an over the rim return and setting up a proper Herbie, since it sounds like a BeanAnimal is more work than a Herbie to set up.

[ZenAle]

Thanks for the response - you bring up some good points. I'm hoping that the pump running dry scenario won't be likely because it's supposedly built to turn itself off in that situation. In addition, I also plan on adding an APEX controller to turn off the electricity to the pump should the water level for the return ever drop too low.

I did notice that it was tougher than I thought to keep a Herbie system balanced and a constant level in my sump. I'm going to go ahead with your suggestion and add an emergency drain to see if that helps.

Given that there is not enough water in the return section of my sump to ever overflow should I get a blocked drain, I'm going to keep the 1" bulkhead as my main drain and he 3/4" bulkhead as my emergency. I know the conventional wisdom suggests to always use the larger pipe as the emergency, but in my case I don't think that's needed and it seems like a waste.

Thank you again for your reply, and if anyone else has any experience/suggestions regarding a Herbie it would be most welcome.

[thegrun]

Is there any way you can drill a hole for a second emergency drain line either in the bottom or back of the tank, if so it is then safe.

[kmbyrnes]

For peace of mind, make the second hole an emergency drain and run the return line over the top of the tank from the back. Quick, easy and as effective as drilling another hole.