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Thread: Tank Overflow

  1. #1
    Junior Member
    Join Date
    Nov 2005

    Tank Overflow

    Hey there,

    Would like some opinions on a new tank being drilled for overflow. The tank will be in the 75-90G range. Knowing what you know now, would you go for a drilled tank with the smaller overflow box and hole in the back of the tank, or the overflow box that goes down to the bottom, with the hole in the bottom of the tank. Of course, please mention any other options you prefer.



  2. #2
    Senior Member
    Join Date
    Sep 2003
    Alexandria, VA moving to Montreal
    I've done a few tanks and I am most pleased with the last overflow. It is known as a "Calfo overflow" named after the author Anthony Calfo.

    It is a full length glass overflow across the back of the tank. It consists of two sheets of glass that you buy at the glass shop and silicone in place yourself.

    You might be able to see it in this picture:

    I like it because it gives maximum skimming efficiency by pulling off the thinnest possible layer of surface water and sending it to the sump. The surface is where all of the proteins are. It also takes up the least amount of space in the tank. All of the bottom is still available for fish and rocks.

    I would advise on two holes with 1 1/2" bulkheads spaced across the top. This will give you more flow capacity than you will ever need. That comes in handy when a snail crawls in the overflow. It also means your tank will be quiet. The extra hole will cost you about $30. You can spend that really fast if your tank overflows, or you have to keep fiddling with your plumbing because it sounds like a waterfall.

    It is also a good idea to buy some flexible Spaflex pipe for the drain lines. This will allow you to run smooth curves that will be less likely to get clogged, and more likely to stay quiet.

    You can do this a bunch of different ways and be successful. Just my two cents worth.


  3. #3
    Moderator cres's Avatar
    Join Date
    Jul 2004
    The Calfo (or Coast to Coast) overflow also comes with a recomendation for lower flow. i.e. Don't try pushing 10-15 times the tank volume per hour through the sump. Anthony recomends more like 3-5 times.

    The majority of your flow should come from the closed loop or powerheads in the tank. Think long and hard about what you think you will want to keep, coral wise, and plan ahead for this flow. This might mean drilling more holes for a closed loop setup.
    Sarchasm: The gulf between the author of sarcastic wit and the person who doesn't get it.

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