On Wed, 27 Jul 2005 11:25:18 GMT, "Carl"
wrote:

Working on a design for a new aquarium hood. Is marine ply going to be OK?
or should I be looking at something else.

Basic design is rectangular frame from Alu or Wood (10x20mm) to sit on the
tank edge. With sides and top from the hood from 5mm marine ply. Top to be
in two parts hinged in the middle. Hope the diagram helps (x is the ply, o
is the frame that site on the glass, with a bi-fold piece of ply on the top
as a lid)

x
xo
xo
x
x


Is the marine ply going to be ok with the moisture from the tank, and the
heat from the lamps? What coating (varnish/paint) be used to protect?

The bi-fold lid with be approx 30cm by 1m. Is 5mm ply sufficient? Need to
keep weight down where possible, but be rigid enough?

Any suggestions?




I've built these for a marine tank of larger size as well as the sort
of size you describe..


Marine ply is very expensive because it is free of voids as well as
being water resistant. For this application, WBP (water and boil
proof) is adequate, readily available and a lot less expensive.

For this size, I would say that 5mm would be just about OK as long as
you are not going to house the ballasts for the lighting in it. If
you are, then I would go up to 9mm.

I avoid using anything metal near a marine aquarium, but if it's fresh
water then less critical. Even so, I wouldn't use aluminium. For
this application, I would construct using entirely wood including a
wooden frame. Glue together with an exterior grade of woodworking
glue or even epoxy.

Use plastic hinges for the lid or avoid hinges altogether by having
the top drop into place on the frame. It's just as effective.

For finishing, I use glass fibre cloth and epoxy on the inside. You
can get this from model aircraft suppliers. It doesn't need to be
heavy grade as the main purpose is to protect against water.

With fresh water, you could use several coats of a solvent based yacht
varnish and get almost as good an effect. Either way, it needs to
cover the inside and the surface in contact with the tank itself.

For the outside, it's less critical and almost anything will do
although should be splashproof at least in case you drip any water on
it.



--

..andy

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