I have to make a DIY hood it's only a small one 24 x 8inches. I'd like to use 6MM MDF but I haven't a clue whats safe to use for sealing the wood as it's going to be near the water. Any help? thanks xx

MDF is hopeless for use around tanks. When it gets wet, and it will, it has the character of a dunked digestive biscuit. The "water proof" MDF is no better, it is, at best, splash proof and will warp in humid situations. Use plywood, and then, make sure your design is such that it prevents warping. Seal it with yacht varnish.

Agree with Lateral line. Plywood and marine sealants are the way to go. Epoxy works well too but its a PITA to work with.

also top tip.

When you create the hood, ensure you batten/make sure that the entire sides are secured to prevent warping, my new tank hood I built which costs me about £60 looks great but the back corners have warped bigtime all the way to where the corner supports is

Going to create a new one, using thinner wood and the mitred edges will be so sealed that Steven Seagul couldn't penetrate it. Might be worth sealing and staining prior to final assembly as well.

Also not sure if this helps, go to your local major DIY store B&Q maybe, and look at their shelving, basic range is about £2.50 for a 3ft pine shelf, buy 2 - 3 of these seal well and you got yourself a great hood!

I am going to build again and heavily photo for use by others, was going to do this weekend but the weather so nice I had several BBQ instead

I got some yacth varnish and plywood I've marked it all up but apparently I'm not allowed to play with the power saw so I have to wait for it to be cut for me! Then I can start sealing and assembling and sealing some more.

I built a hood for a 65 gallon 3 years ago, marine grade plywood, oil base paint products with a couple final coats of marine varnish. After 2 years you could see some water penetration/damage, I imagine you have to do yearly maintenance with it just like a boat.

After 3 years I'm going to have to pull the plywood off & redo it, which is no big deal. It gives me a reason to hang out in the garage & shoot the bull with the neighbors. I'm thinking of going with a solid wood instead of plywood this time. The framework is good, made of solid 2x2's, which makes me thing a solid board is the way to go as opposed to plywood.

I make my hoods from solid wood. They warp on the opening parts a little, but I have never got around to sealing any of mine and have not yet noticed any problems. One has been in place for over two years, and one is now at one year FW and one year SW with no apparent problems or rotting (though it is darkening where the MH is so close to the top of the hood)

As far as I can see it is 20mm pine I have been using.

That sounds like the route I'm going to take Andy. It should be an easy switch, using the old panels for a pattern.

When I built my canopy I used polycarbonate sheeting to reduce he amount of water and condensation that rose to the timber frames. This is really handy stuff to work with and can be cut to overlap itself, giving you a good seal. A discription and pics are available Here