# Spray Foam for DIY backgrounds



## cancichfan (Dec 23, 2009)

I figured that this had already been discussed many time but I didn't find it in a search of the forum.

Has anyone used spray foam (the type that expands for sealing around windows and doors) for building a background? Is it toxic? I just thought it would be easier to apply it in blobs over the background backing and then carve it rather than carving down styrofoam. But, since I don't see anyone talking about using it, I assume something is wrong with it.

I was going to use cor-plast for the backing (looks like corrugated cardboard but is plastic) as I have a bunch of old signs made from this that I could use. Then, I thought I'd play around with adding the foam in various spots and see how it looks.

I am hoping to get a 29 gallon in the future and thought I'd play around with a background for it.
Thanks
Graham


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## cjacob316 (Dec 4, 2008)

i asked about it before, and the only real problem is that if you plan to spray it directly into the tank and carve it in there, then sealing it and cleaning out the pieces could be a pain, but it's not toxic to my knowledge and i have seen it used to fill in spaces on styro backgrounds


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## mightyevil (Oct 23, 2008)

You can use pond foam which is perfectly safe for fish use, I have also used "Great Stuff" to success. It is much more difficult to work with foam than it is with styrofoam, at least in my experiences but it also comes in handy very much. I would use a thin piece of styro and make the foam background on that, rather than inside the tank, it would be much easier.


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## cancichfan (Dec 23, 2009)

Interesting. I thought that Great Stuff type foam would be easier because you could apply it in different places and build up depth. But, I guess it is probably a lot harder to cut.

My intent was to use the cor-plast outside of the fish tank. If you cut it on one side, but not all the way through, you can bend it 90 degrees and then I was going to use the foam to secure the corner and build an L shaped background that would slide into the tank and then glue into place with silicon. Probably not describing it right but the entire piece would be built outside the tank and then slid in.

Curious - how do you ensure adequate circulation for water intake and heat transfer? I have seen others on here that have cutouts for these but how much room do you really need to make sure that you don't get heat buildup or lack of flow?

If I do this, I'll try to take pictures. Just glad to hear that the foam doesn't appear to be toxic. 
Graham


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## mightyevil (Oct 23, 2008)

Here is one of my videos showing the equipment in my old tank with a DIY background. Hopefully it helps!


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## cancichfan (Dec 23, 2009)

Thanks. Interesting musical selection for the video...

Just wondering, putting the heater and intake together like that, does the water cool down as it moves through the filters? Would the return and heater together be as good? Just thinking that would put the warmth into the tank but it probably doesn't matter. 
Also, I've seen Drylok mentioned a lot of times. What is that? I have some hydraulic cement I was going to use (just because I have it).


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## Pali (Dec 22, 2009)

I have worked with regula building foam used for sealing window and door frames, when it's dry it don't give out any toxins in the water.

Last time I used it I got a great tip from a friend, that worked great. Spray the foam into a plastic bag and then shape it as it exspands, after it's dry it's alot easyer and less work to get the final shape you want. Finaly cover it with cement or what ever your useing for final coat.

I filled the bag inside the tank, getting the size I wanted, then waited a bit till it was done expanding and holding it's shape. You can till mold it in this state and put it back in the tank to dry when u got it shaped, you can also lay the tank down and mold it inside the tank keeping it there the whole time.

When it's dry you peal off the plastic bag

Have fun!


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## mightyevil (Oct 23, 2008)

cancichfan said:


> Thanks. Interesting musical selection for the video...
> 
> Just wondering, putting the heater and intake together like that, does the water cool down as it moves through the filters? Would the return and heater together be as good? Just thinking that would put the warmth into the tank but it probably doesn't matter.
> Also, I've seen Drylok mentioned a lot of times. What is that? I have some hydraulic cement I was going to use (just because I have it).


About the music, yes I know. 

Doesn't matter which way you put the heater, intake output, its all the same. My tank was always about 82 degrees F with that one heater, worked very well for me.

The Drylok is some sort of latex based paint. You don't need to use concrete unless you want to. Many people have problems with PH and cracking with concrete. Drylok will give you none of those problems and it cures extremely quickly compared to the 28 day rule for concrete. One of my tanks has a Drylok background, has been up and running since November 23 and no problems yet, as a matter of fact I have had cichlids spawning in there since.


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## mightyevil (Oct 23, 2008)

*PALI*

using a bag for the foam is a great tip, very clever but having worked with foam before, I still think it is more of a hassle to work with it than with styro. Another plus about using the "Great Stuff" foam is that is stronger than styro and more forgiving when accidentally hitting the material and potentially breaking or cracking a part of the background.


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## cancichfan (Dec 23, 2009)

So, here is one learning.
I had a couple of old spray foam cans in the basement from when I did a new dryer vent and I thought I'd just play around a bit and see what this stuff looked like on plastic. I was able to coax some out of one of the cans but the other was plugged up. I took off the applicator but it was plugged in the nozzle. So, I tried to clean it out with a nail. Shoved the nail in and nothing happened. Shoved it a bit harder and nothing happened. Shoved it a bit harder and something happened. Something really happened!

Luckily I am due to shave my head anyway because I have spray foam in my hair, on my clothes and our freezer has insulation on both the inside and outside of the lid now. Think of the money I am going to save on electricity! One half of the plastic looks pretty good because I was able to control the application rate. The other half is a bit more free-form.

I think I'm on the right track, I just need to control the application rate a bit better.

Also, does anyone know what dissolves this stuff?
Thanks
Graham


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## mightyevil (Oct 23, 2008)

Wow 

I would try something like acetone or paint thinner. Beware of using it on color though, it will take it off. Other than that I don't know what to tell you... live and learn :lol: :lol: :lol:

Thanks for sharing the experience!!!


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## cjacob316 (Dec 4, 2008)

if you get some new cans, and finish up the project, get it painted what not, shoot us some pics

good luck with the hair, try a chisel on the freezer haha


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## cancichfan (Dec 23, 2009)

I tried putting some hydrualic cement over the foam that I had started with. This one is only to see if it works. I have had some other ideas for the "real" one. I mixed the cement thin and poured it on, brushed it out where necessary etc. The colour of this sort of cement is darker than regular, more of a slate grey. It also hardens quickly. It actually looks pretty good but I need to wait for it to set up so that I can see how well it sticks to the foam.

I used it because I had it on hand but I think that Dry-Lok will be better as suggested in some other posts. I just didn't want to lay out $30 for a gallon of paint until I get further along.

The real reason for this post though is to ask for some advice on posting pictures. I am going to document the next attempt. How do you post the actual picture on a message? I can get the photobucket link on but not the picture itself. Any thoughts?

I am gonna take a shot at something this weekend so I'll take the pictures anyway and figure it out later.
Thanks
Graham
P.S. The foam came off the freezer pretty well. It didn't stick too tight to the metal. I sacrificed one T-shirt and the last remnants of my hair though. But, like I said, I was gonna shave my head anyway. See, this way no one can tell I'm going bald in my 30's. I am sure I'm fooling everyone...or maybe just myself.


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## cancichfan (Dec 23, 2009)

cjacob316 said:


> if you get some new cans, and finish up the project, get it painted what not, shoot us some pics


Since you asked, here is a shot of the completed second attempt for a 29 gallon tank I am setting up. I will need to get a lot more rock but this give you the idea of the spray foam. You may notice a tube in the foam, this hooks to my filter intake and I have black foam to go into the end of the tube (there is also a return tube that isn't apparent in this shot). I don't know if I'd do another spray foam one. The shot doesn't show the colour that well but I think once it is covered with algae, it will be OK.

I had to do a side-on shot because the flash kept obscuring the picture but face-on with overhead light for shading it looks pretty decent for a first attempt.










Thanks
Graham


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## cjacob316 (Dec 4, 2008)

the light spots, is that the foam or paint?

looks good, kinda like bassalt


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## Mcdaphnia (Dec 16, 2003)

mightyevil said:


> *PALI*
> 
> using a bag for the foam is a great tip, very clever but having worked with foam before, I still think it is more of a hassle to work with it than with styro. Another plus about using the "Great Stuff" foam is that is stronger than styro and more forgiving when accidentally hitting the material and potentially breaking or cracking a part of the background.


I got two free 75's because someone went crazy with Great Stuff as a background up to a foot thick that cracked the glass as it continued to expand after solidifying.


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## cancichfan (Dec 23, 2009)

The really light spots are actually the foam. One reason I wouldn't do a spray foam one again, or at least would do it differently is because the foam seems to keep expanding for a very long time. I let it cure for several days but when I painted it, cracks started to appear. I touched up a lot of them but finally decided that I will let the algae do the final touching up for me. I also saw a thread on another forum that described using a "pond" landscaping foam which came out a much darker gray. I would try that next time instead.

In the tank, you really don't see the white spots at all, the flash seems to really bring them out.

If I did one again, I'd foam it, carve it a bit and then leave it for a few weeks before painting it.

I'll post another shot with a camera that I can turn off the flash after I get water in it and top light. Not sure what bassalt looks like but it certainlyl has a "Lava" like quality to it. Would be great for those Hawaiian cichlid tanks.


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## cancichfan (Dec 23, 2009)

Mcdaphnia said:


> I got two free 75's because someone went crazy with Great Stuff as a background up to a foot thick that cracked the glass as it continued to expand after solidifying.


I would definitely build it on some sort of background first and then place it in the tank afterwards. I can't imagine how you'd ever get this stuff off the glass. Mine was done on cor-plast signage which is essentially a plastic version of cardboard that I siliconed in place.

I am not surprised about the continued expansion. Like I noted above, this stuff seems to slowly expand for days.

My next attempt, for my 90 gallon will likely be regular white styro with some of this applied to specific areas to build up depth.

I tried the bag method to in an attempt to build some rocks. Not good. Because the foam couldn't gas-off to the air, the stuff inside the bag took forever to dry and then the texture was really weird. I had a normal crust of foam on the top but the rest was odd. I put a couple of "zip" ties into the foam when it was wet and I was going to use them to tie the foam to egg crate to keep it down and carve caves into it but like I said, the texture was really weird, very crumbly and coarse. I'm not saying the bag method doesn't work, it just didn't work the way I did it.


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## Mcdaphnia (Dec 16, 2003)

cancichfan said:


> ....I would definitely build it on some sort of background first and then place it in the tank afterwards. I can't imagine how you'd ever get this stuff off the glass....


 I used a carpenter's hand saw to cut out the bulk of it, then razor blades. In some areas it had popped away from the expansion pressure. I was really tempted to use a pressure washer on it but since there was some glass chipping on the tanks plus the cracks, it would have been too dangerous with tanks in that condition.


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## cancichfan (Dec 23, 2009)

Just bringing this back up if anyone is interested in what I learned from a spray foam experience.


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## mightyevil (Oct 23, 2008)

Mcdaphnia said:


> mightyevil said:
> 
> 
> > *PALI*
> ...


Wow  ! I didn't know it would keep expanding after the "expected time to cure". That is interesting and yet another reason why it is easier to work with styro.



cancichfan said:


> Mcdaphnia said:
> 
> 
> > I got two free 75's because someone went crazy with Great Stuff as a background up to a foot thick that cracked the glass as it continued to expand after solidifying.
> ...


Yes, do the white styro, less hassle IMO :thumb:

Makes sense that the bag trick didn't work, I would assume that it would stick to the bag and when cured it would be difficult to remove the bag without leaving pieces of it in the background.


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## cancichfan (Dec 23, 2009)

No, the bag came off easy enough but the texture was off. Live and learn.

It's stuck in the tank now and the water is in, just need to do some filter adaptations and add rocks and I'll post another shot. Having a real hard time finding fish though. Nobody around here seems to have shellies and Julies or Calvus. Now if I wanted neon tetras...


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