Waterfall and Foam Safety

[Nath514]

I have been changing my mind every 10 minutes as to how I want to go about building the waterfall for my tank.

Design:
I want to have several small pools that the water falls between as it makes its way down. I want the waterfall to be a greyish color since the rest of my background will be a silicon ecoearth (brown).

Methods:
1. Use styrofoam to create the shape of the waterfall and then use grout to fill it in and paint it.

Problems: Is the foam safe, is the grout safe and will it hold up to constant water, will the paints seal it. What is the safest type of styrofoam

2. Use Great stuff or another expanding foam and then cut the waterfall out of it, and then grout and paint

Problems: Will the grout stick to the foam, is this any safer

3. Some other awesome method

Want something similar to the falls in this video

You Tube

You Tube

Thanks

[bastimentos]

the fall in this video looks to be made with grout and gs (way #2)

[Pumilo]

All styrofoam is a known endocrine disruptor and could present problems. It is safest NOT to include any styrofoam in your build.

Simple/Functional; The JBear Way
Safety of styrofoam?

Great Stuff would be a safer choice.

[parkanz2]

I agree with using great stuff. In order to get anything to stick to it, you will need to carve or roughen the smooth surface (you'll see what I mean after you let it cure). Not a big deal but you'll be cursing if you try to apply grout without a little surface prep.

[J Teezy]

yes styrofoam / polystyrene is a know endocrine disruptor but just somethings here:

I've used polystyrene in making rock wall backgrounds, but when i use it it is completely covered (front, back, sides, etc) with something. Several layers of grout, non toxic acrylic paint, non toxic shields all sealer, and then silicone. Now can the endocrine disruptors break through all these barriers? I think the risk is more an issue with exposed polystyrene but once you have all these barriers I personally think the risk is much much much lower (i'm no scientist but i'm just going with the idea that silicone is used in tanks to seal them from water leaking so wouldn't it seal the polystyrene as well, and not to mention that its also covered in several layers of grout, acrylic paint, and shields all. Now of course after awhile silicone could dry out and rot but then the shields all barrier is still there, paint and grout.

As mentioned the safest thing is to not use it, but lots of people do, i think the important part if you use it is the steps you take to reduce the risk of any issues occurring.

Now also depending on what you are actually trying to build GS method can be easier and take less time to construct backgrounds. I know when i make a rockwall fixture from polystyrene it takes many many hours of me constructing it not to mention the added wait time of each grout layer drying, paint drying, shields all drying, silicone curing.

I'm getting ready to do my first mostly GS background now, but i used polystyrene again as the framework but it will just about all be covered over in GS then silicone and peat / coco mix. I don't like the idea of spraying GS directly on the glass of my vivs as in the removal of it down the line if i need to. I make my backgrounds so they are easily removable if so needed so i used the polystyrene in this build as the framework. Also i like being able to create the background outside of the tank especially when working with a fish tank where the only access is through the top. The idea of tyring to carve a background while its in the tank seems like a headache to me. Eggcrate would be another possible framework i could have used but i didn't feel like going to the store to get it as i have alot of polystyrene on hand. I'm also wondering how well spraying GS onto something like wax paper would work. If i can find some to build a framework out of that the GS doesn't stick to i'll probably do that on the next build

[suztor]

I know this thread is a little old buuuut

I used a fresh piece of acrylic to spray the GS to it mostly came off clean but the acrylic turned out to be one time use.

I've tried aluminum foil... that was a no go ( i was cursing myself as i tried to peel off all the little bits and pieces...

I know it's silly but has anyone sprayed GS straight on to water? how does it cure? does it give it a flat texture?

~Sue