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Re: Glass for Tank Top

At 06:40 PM 6/2/2003, Scott Heiber wrote:

Feeling fed up with glass and all the tint, heat sensitive,
and cost issues?   Well, acrylic has none of the heat
sensitive or tint problems .  No glass has as high a
transmissitiy as good acrylic but acrylic absorbs water --
not a lot but just enough so that it will warp if both
sides are evenly exposed to water/mositure -- like when
placed over water (polycarbonate too).  You can reduce or
prevent warping by using a really thick piece  (3/4"),
apply ribbing, or having other reinforcement, like cemented
box sides.  This is all rather cumbersome and, anyway, more
expensive that some of the fancy glass.

There are a couple of other options to avoid Acrylic warping:

    * I have the same tank as Rachel (72 gallon bowfront), along
      with an AHS 4-foot plywood hood. The hood can be used as
      a stiffening base for the acrylic: One piece covers the hood
      bottom, two hinged hatches in the front, two hinged hatches
      with cutouts in the back. Or skip the back pieces and use
      something else that doesn't warp.

      This solution allows the use of highly transmissive, thin
      acrylic under the lights, and thicker stiffer acrylic for the
      hatches. A disadvantage is that the hood can no longer
      be slid back and forth, because the front hatches are fixed.
      An advantage is that the hatches can be held open with a
      velcro dot.

    * When I bought some steel bars at Home Depot to reinforce
      the dresser that supports my 800-plus pound tank, I noticed
      some small channel stock and L-stock that would do a nice
      job reinforcing one edge of a sheet of acrylic. But I decided it
      was just easier to screw the acrylic to the hood as above.

Finally, consider using no cover at all. I've been without one for several months without losing any jumpers. This is not an option if you have Hatchets other famous jumpers, but none of my fish have the urge to explore the universe above. Humidity is up, but this is a good thing in dry California.