Very necessary HOB overflow mods

Discussion in 'Equipment' started by Justin Daugherty, Oct 12, 2014.

  1. Justin Daugherty

    Justin Daugherty Guest

    Aug 7, 2014
    Likes Received:
    my preference would be to run my tank drilled with built in overflows but I setup my aio long before I decided to add a sump and didn't even consider it. When it can time to plumb my sump, tearing down to drill just wasn't an option so I'm stuck with the dreaded HOB overflow.

    They are notorious for causing floods and being noisy. Let me show you what I've come up with to solve these issues:

    I removed the stock pipe and stacked progressively smaller pieces of floss in the overflow compartment. I also filled the tank side of the overflow with bio balls so it breaks up and distributes the flow of the incoming water. It's effectively silenced.

    I drilled the side just offset from center of the water line and installed a bulkhead so that it sits mostly dry. The primary overflow is filtered with the floss and feeds my sump. The secondary overflow just trickles but is big enough to handle all the flow of my return pump so if the primary plugs or slows, the water level raises and the secondary handles it. The normal trickle of the secondary is great to feed a fuge or can just dump into the sump alongside the primary. Since I have a second overflow drain, I run a bigger return pump than I would have otherwise so my flow rate through the return is fairly high. The flow through the "u" clears any air that could get in it immediately. Also, the bio balls break up the incoming flow so I don't really get micro bubbles to begin with.

    I remove and rinse the floss and bio balls once a week to prevent any detritus build up or nitrate production. I've been running this way for two years without any issues or "close calls". I'm just as confident in this setup as I've been in any drilled tank and really pleased with how quiet it is.

    If you're running a HOB overflow consider modding it and you'll be glad you did!

    Justin (San Francisco),
    sent from tapatalk
    neuro likes this.
  2. denzil

    denzil Webmaster

    Aug 1, 2012
    Likes Received:
    Very nice, thanks for sharing that!

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