Foam rock walls....

[Greatreefer]

In reading an article on making foam walls:

http://ottawainverts.com/2008/12/13/building-foam-rock-walls/

I saw that is it recommended to remove all the air from the foam by pushing on it after 20mins of applying . Is this really necessary or, is it only used to reduce the buoyancy of the foam.

[customcolor]

you know that the foam is full of super small holes through out the foam...that is why its so buoyant... i dont get why they are saying push out the air??? if you could do that it would change the shape...its just an extra step that may not be needed....i say that cus i did 3 tanks already and i didnt do it...oldest tank with the foam is 2 years old now

[seventhz]

Well, my guess would be that pressing the foam isn't so much about reducing its buoyancy because the weight of the rocks will most likely counter that. I would have to assume that pressing the foam serves two purposes, (1) to increase the holding strength of the foam to the egg crate and the rocks, (2) to minimize the amount of gases that are trapped in the foam. If you've ever used "Great Stuff" then you'll know that it expands something like 5-10 times the size that you apply... you may put down a little 1 sq. inch portion and within minutes it could possibly expand to a 6 sq. inch section. Further more, let's not neglect the fact that it is a man made chemical designed for insulation purposes and not for aquariums so I must assume that it can produce some nasty gases that will be trapped inside the foam if you don't press it out and the last thing that you want is some little foraging critter to puncture a weak point in the foam and releasing those gases into your controled enviroment... who knows what that could do to your water quality. I love the idea and I'll have to keep that one in mind but in my opinion, I would definately press the foam as it cures.

[Greatreefer]

what about epoxy glue?
The one that is mentioned though out this form and in this DIY article I'm reading says to use "Z-POXY". I was wondering if you could use a marine paint or, somthing thats a little more spreadable than the glue.

[likwidglostix]

Actually, once Great Stuff cures, it becomes completely inert. Although you may want to coat it with an epoxy as it may get abused by a curious tank inhabitant. I've heard of some people coating it with fiberglass resin, then coating in sand and/or crushed coral while it's still tacky. Gives that natural look, whereas the foam would look wierd because it forms a skin instantly. I've also heard bondo is a great alternative and you can sprinkle some natural materials right on it in addition to shaping it just like you want. You would have to as it's pink and there's nothing natural about that.

[Greatreefer]

likwidglostix, do you have a foam wall installed if so, what type of epoxy did you use?

[CaptHook]

I know the answer to this one(from reading past threads,check the archives) I wrote down for future use:Marine Grade 2 part epoxy.I just ordered some thru my Sherwin Williams paints and whats even better is that they can color it to whatever you'd like.I got purple so when the coraline starts to grow on it,it should all eventually blends well.Good luck on yr project