Aqarium Hood - Marine Ply?

[Carl]

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?

[Andy Hall]

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.

[Carl]

Great! Someone who had already done this!

Its been on on these projects "in the pipeline" for a while

Not worked with ply much before, and appreciate the tip! Trust this is avaliable from my regular timber merchant.

Intention was to run the lighting as an Arcadia T-bar

with the lighting fitted on "runners" on the tank from so that it can move forward and backward to gain access to the tank, without having to remove the lighting unit. In this setup there is no additional weight on the lid.

Great Tip? Plastic hinges may be hard to source, but two panels work work ok, and as you suggest be easier.

It is a freshwater tank, so I will consider both options.

Final color will be black, so I am sure something can be found to acheive this.

[Andy Hall]

It should be. 18mm is very readily available but the other sizes should be as well even from DIY stores.

OK. Don't forget to fit an RCD on the supply to the lighting.

I have one for the lighting and a separate ones each for the heaters and pumps. The main risks you have are the lighting assembly falling into the water, then with heating and pumps some sort of leakage or breakage.

The idea is that if one thing goes, it doesn't remove the supply to everything.

The most critical aquarium issue is oxygen, but as long as you don't overstock the tank then loss of power is not a short term problem - there is enough absorption at the surface.

Especially as you aren't fixing anything to the lid. To be honest, in that size, making it as one piece would also be OK.

Don't forget to allow some ventilation. Conventionally this is slots or holes at the back. Otherwise, you run the risk that the heat from the lighting will raise the water temperature too much.

[David Lang]

Wickes stock WBP ply 6mm, 9mm & 12mm thick in 6' x 2' or 4' x 2' sheets as well as 8' x 4'. They carry 18mm in 8'x4', 8'x2' or 4' x 2'.

Dave