Rygh's 250 gallon upgrade

Discussion in 'Tank Journals' started by rygh, Jul 17, 2010.

  1. GreshamH

    GreshamH Guest

    Ah, #2... WAF, very important (Wife Acceptance Factor)

    sure you want to bolt it to the wall? Bolting it will hold the stand in place but not necessarily the tank. Most people I trust say not to bolt it and to allow it to move as a unit.
     
  2. rygh

    rygh Supporting Member

    Hmm, from a physics/engineering standpoint, that seems like very strange advice to me.
    But of course, some merits. Certainly made me think a bit. See below.

    For toppling: Bolting it to the wall is a HUGE advantage here.
    For this, you need to look at where your center of gravity is versus the pivot point.
    Unbolted, your pivot point is at the floor. (Unless stand can slide, which is very unlikely)
    now your center of gravity includes both the tank + stand, but the stand is largely
    insignificant, so center of gravity is just a bit below the center of the tank.
    So with a 24" tank, 30" stand, your CG is about 40" about pivot.
    Bolted, your pivot point is simply at the bottom of the tank, where it touches stand.
    So with same example, your CG is only 12" above pivot point.
    Very big difference.

    For STAND collapsing: Bolting it to the wall is a HUGE advantage here.
    Obviously.
    And this is one of the most likely failures in my mind.
    The stand sure seems like an easy thing to break.
    You have a huge sheer force on a box that is mostly built to be strong vertically.
    In my 250G case, if the floor moves one way, you have 2000 pounds pushing the other way, due to momentum of tank. T
    hat is huge. Plus, even if stand does not break, you have an issue with twisting of the stand.
    And that twisting can cause the main tank to crack.

    For TANK collapsing: Advantage to not bolting.
    Here, it comes down to pressure differences.
    Unbolted, things flex, and you get less pressure from the momentum of the water slamming against the sides.
    Much like problems if you do not have your aquarium level.
    On the other hand, the pressure difference will only be a few inches. It sloshes over the top.
    So hard to think it will break, unless it is pretty close to failure already.

    For water sloshing out: Advantage to not bolting.
    Like above, things move, so less pressure, so less sloshing of water.

    So overall, it seems that for a minor quake, it is better to leave it not bolted.
    But for a big one, in terms of massive failure, it is better to bolt it.
    Risk tradeoff.
    So bolted, I have a higher percentage chance of moderate problems, but a lower percentage
    chance of total failure.

    Other ideas? I am certainly curious.
     
  3. GreshamH

    GreshamH Guest

    All the aside, my recommendations come from those that have weathered earthquakes. Northridge and Loma Prieta FWIW. Bolted tanks had a much higher failure rate then unbolted (which only lost some water).

    One facility I know in the Northridge quake was built on cinder blocks. Only lost water, nothing toppled. His customers had total failure with bolted tanks.

    Quakes don't always play nice when it comes to engineering. This was proved countless times in the last couple large quakes Cali has had. Every new quake give new data points and something new is always learned.
     
  4. rygh

    rygh Supporting Member

    Hmm.
    So maybe I am under-estimating the odds of the tank itself coming apart.
    As mentioned, it does make sense that a bolted stand puts a fair bit more stress on the tank itself.

    Although key to that : Were most of the failures Acrylic or Glass??

    Interestingly, if the failure point moves from stand to tank depending on build,
    then what you should do to prepare for an earthquake should also change.
    Perhaps glass = unbolted, acrylic = bolted.

    On the other hand, conclusions from semi-random, non scientific sampling can be problematic.
    I am not saying that it is wrong, but it is something humans are notoriously bad at.

    But I wrote this on the internet, so it must be right. :)
     
  5. gimmito

    gimmito Supporting Member

    Cool tank. 8)
     
  6. rygh

    rygh Supporting Member

    Earthquake design decision:

    So, after mulling the advice for a night, and thinking more about how the pros do it on buildings, I
    decided to do a "loose bolt" compromise.
    Basically, I will have some small dense 1" x 1" x 1/2" thick foam pads in a few spots.
    Plus, I will get longer bolts, put a 1/2" thick foam pad washer, then a big thick real washer.

    Thus, it will be able to move about 1/2" in any direction against the foam.
    Should help a lot in taking out the sharp jolts.
    Yet still keeps things from toppling and collapsing.
    Very much like they do on large structures, such as bridges.
    As a bonus, really easy to implement.

    Side note:
    I have been through 2 big quakes myself. And we suffered a fair bit of damage in the LA quake in 71.
    So I take this fairly seriously.
    Funny : You think water sloshes from an aquarium. The amount that comes out of a pool is amazing.
     
  7. rygh

    rygh Supporting Member

    Thanks in a large part to your thread btw. Otherwise I never would have known about the steel rim option.
     
  8. tuberider

    tuberider Guest

    If my tank comes crashing down in an earthquake (150g), that's the last thing I'm gonna be worried about you can bet...
     
  9. sfsuphysics

    sfsuphysics Supporting Member

    Yeah, something strong enough to knock my tank over... probably won't have to worry about the tank... although in reality it probably would be high on my list of things to check on (assuming my house is still standing :D)

    As to bolted vs unbolted.

    The problem I think comes from two different view points. If you view the stand + tank as a whole, then absolutely bolting makes sense. However because they are separate you have to treat them as such as far as movement. For tipping it's ALMOST the same, however an earthquake of sufficient strength will more likely shake it all rather than simply push it from one side, what this means is that the stand itself can shake and move as well as the tank, a little less so on the tank because there could be sufficient friction. But most of all if you bolt it, and only the tank can shake you're probably looking to have a tank that might shake a bit off the stand, and if it's something like a glass tank with a rim being on the corner of the stand could have catastrophic consequences.
     
  10. rygh

    rygh Supporting Member

    Started on New Big Sump

    On to more exciting things that fire/quake safety. Funny where threads go sometimes.
    SO:
    My old sump was a bit small, and perhaps even more importantly, the wrong aspect ratio, so stuck out too far in the garage.
    Plus I was not happy with the liner.

    Time to make a new sump!
    I am doing a plywood box, lined with 1/8" acrylic. Same as previous refugium, similar but improved from old sump.
    Box will be 40" long, 24" wide, and 40" tall. Water level about 4" below top, to allow for overflows.
    Walls are thick and very strong.
    It ends up being 115 Gallons. A good percentage of a 250 gallon tank.

    The nice thing is that the wood/acrylic/etc ended up being about $150, so pretty cheap for a 115 gallon tank.

    Construction:
    Basically, the walls will be a laminate:
    • 1/8" Acrylic
    • 3/8" Plywood
      1" Stringers(studs) / insulation foam (between studs)
      1/4" Plywood.

    The Acrylic will be glued to Plywood with epoxy. (Sand Acrylic first)
    Ply/stringers are glued with waterproof wood glue, and screwed.
    It all acts like a big I-beam, so while plywood is only 5/8" total, it should be equivalent to 1" or more.
    There will be a small top beam across the top in the middle as well, since a 40" span is fairly large.

    A big bead of thickened epoxy will be used where all the walls/floor meet.

    With 1" insulation, plus all the wood, I expect a pretty good R factor.

    There are a few tricks regarding the way the inner/outer skins overlap as well, to increase strength.
    Plus, a few bolts will be used in key spots.
    It is 40" deep, so a considerable amount of force. Not to be taken lightly. (Ugh.)
    For the curious:
    The total force of the water, against the main walls, is 854 pounds, with a center of pressure 12" from bottom.
    The total weight of the water is 961 pounds.
    (FYI, force of water and weight are not directly related. Only similar due to 2-1 aspect ratio of height/width)
     
  11. rygh

    rygh Supporting Member

    I think I need to change the name of this thread.

    I did a very exact measurement and calculation of volume of the display tank.
    To real water level, and subtracting overflows.

    Ended up at only 216 gallons. :(

    So much for a big school of Unicorn Tangs.
    Well, with sump, system will be over 300. So maybe only 5 or so. :)
     
  12. gimmito

    gimmito Supporting Member

    You might want to check with Arnold (Apon) regarding plumbing, lighting (they had a sweet 6' giesseman mh/t5 setup), qt's, & sumps. Not much live rock left, but they had synthetic looking rock.
     
  13. rygh

    rygh Supporting Member

    I will be done with my new sump soon, probably next week.
    Lighting will be all LED. Already did a test module for color.
    QT tank will be my old refugium.
    Live rock is something I am looking for though. But not just yet.
    I have a bin of dry stuff out back still. May be enough.

    Basically : For me, a lot of the fun is the build. So not about to buy anything if I can help it.
     
  14. rygh

    rygh Supporting Member

    Started a separate thread on the sump.

    Here:
    Sump thread
     
  15. rygh

    rygh Supporting Member

    Well, sump is basically done, so back on track here.
    Mini task: Improved overflows.
    Next major tasks:
    1) Plumbing.
    2) Start on LED Lighting design.

    I bet there will be a few opinions on LED design. Always a fun topic.
     
  16. rygh

    rygh Supporting Member

    Well, the fish "room" in the garage is starting to take shape now.
    Sump (lower box) is in.
    One Algae Turf Scrubber (upper left) is in.
    Ventilation is started, but lots of parts lying around.
    Holes between garage and family room are done.

    [table]

    [​IMG]



    From Aquarium_Release

    [/table]
     
  17. JAR

    JAR Supporting Member

    It all looks kind of temporary. Are you planning to beef up some of your "shelving"?
    I can hook you up with a few 2x4's if you need some. :D
     
  18. rygh

    rygh Supporting Member

    Good eye, yes, sort of temporary.
    I plan on putting shelves below the ones shown, for dosing bins, and misc storage.
    Improved bracing will come directly up from those.
    And an extra cross-brace will go in after ventilation is done.

    However, the turf scrubber filters are very light. Only 1/2" of water in the bottom when running.
    So the current bracing on upper shelves is technically good enough. IF nothing goes wrong, which it always does.

    I have plenty of wood, but definitely appreciate the offer.
     
  19. Kraylen

    Kraylen Guest

    A lot of hard work into this bad boy... awesome :)
     
  20. rygh

    rygh Supporting Member

    Appreciate that. But ugh, is it ever a lot of work.
    I pretty carefully itemized the tasks before I started, so not unexpected, but it seems like nothing is going smoothly.
    The big frustration is spending so much time, and still not having a drop of water in the tank.
     

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