Re: Tank Tops

[Wright Huntley <jwwiii at pacbell_net>]

Edd.Kray at rf_doe.gov wrote:

> One of my tasks, before convention time, Is to replace all the old and
> broken tops on the tanks down in the fishroom. I'm still using your basic
> double strength glass tops on my 5's and 10s. Of sourse they occasionaly
> fall into the tanks, fall on the floor, whatever , and I end up with a few
> "topless" tanks , or a few with tops that are taped back together where
> they have broken in just two pieces.
> 
> Has anyone developed a better solution for tank tops. Of course, I've tried
> plexi but it droops within a few weeks and becomes unusable. 


Acrylic (plexi) absorbs water on one side and expands, to make the tops sag 
in the middle. Use Lexan o/e to avoid this problem. Since acrylic has such a 
very low melting point, many (not all) of the plastic covers sold for 
fluorescent ceiling fixtures are made of some form of polycarbonate 
("Lexan"). It is tougher, but still cuts fairly easily with a draw tool.

Avoid the glazing stuff, as it is too expensive. Look in the lighting area 
for the 2'X4' ceiling panels. They are thinner, but way cheaper, usually.

> I considered
> trying to reinforce a piece of plexiglass with some simple rigid brace
> system to keep it from  warping but havent decided what would work for
> this.


Easier to just start with polycarbonate. It does not warp at all.

A 1/2" wide piece of the same acrylic *can* make a center brace that stops 
warping, too. Glue with the standard acrylic solvent "welding" liquid.


> 
> What do you guys use for a tank top (5 and 10) that doesnt get broken nor
> does it warp? Any innovative ideas out there.


I use George's solution on "Critter-Keeper" type tanks, to cut evaporation 
way down. Stretch Saran Wrap over the top, and poke holes for airlines near 
edges, and a bigger one under the center flap for feeding.

I use plastic planter saucers, inverted over drum bowls, for the same 
purposes. Easy to drill for lights, airlines, etc.

Glass is still my favorite, based on low cost, ease of cutting, mobility, 
cleaning properties, etc. [I just regret it when I make too many, too fast, 
and forget to adequately sand off any sharp edges.]

Wright


-- 
Wright Huntley -- 650 843-1240 -- 866 Clara Dr. Palo Alto CA 94303

Ask of politicians the ends for which laws were originally designed, and 
they will answer that laws were designed as a protection for the poor and 
weak (...) but surely no pretence can be so ridiculous(...). -- Edmund 
Burke, A Vindication of Natural Society, 1756


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