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DIY Styrofoam/Drylok Aquarium Shale Wall Background

76K views 142 replies 11 participants last post by  Deeda 
#1 ·
Hi Everyone.

I've been working on a background for about a year and a half, and should be ready to install it in my tank soon. This background will be for a 75 gallon US Native stream/river tank, and I wanted to try and build a biotope that you might find in one of our local rivers, all of which have shale formations along the river bank. I also wanted to create something that I haven't seen before, so my intent was to have the faux slate stratification at a downward angle. Since much of my research came from this forum, and many of your paved the way for guys like me, I figured that it was time to give something back and show you not only what you've taught me, but what I figured out on my own as well, and we can finish this project together.

The background was carved out of styrofoam boards, then each glued at a 45 degree angle or so when they were done carving. I measured as I built it up. the gap behind the foam board and base were filled with spray foam and river rocks (to reduce buoyancy). I used Gorilla Glue to bond the styrofoam boards together and also used plastic popsicle sticks to help stabilize and bond them. On the left side, there is a PVC pipe that goes down into the background with an intake that I made for the intake tube of my canister filter. There is a removable section of carved foam covering it that allows me access to clean and clear the intake of debris. The part that sticks out of the left side hides the intake.

The pics and video below show what the background looks like today. In the subsequent posts, I'll show how I constructed it. Hope you all enjoy it and thank you for all of the posts of your backgrounds that helped me!

View from the left side:


View from the right side:


Video:


The paint is the second coat of Drylok, tinted to resemble the base rock color of our river cliffs. The first coat was just Drylok gray. I will be stippling lighter shades of this color a few times to make the rock less monotone and more realistic, and then finish with light color highlights. Construction steps to follow in the next posts. It may take me a few days to get this thread going to the point we are today. But, I'll start with my first steps.
 
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#83 ·
Thank you Kipnlilo! I'm very motivated to finish this up now that I can see the light at the end of the tunnel. Plus, I have another tank project that needs to be done, and this one is holding everything up!

I took a few pics of the latest version of the roots in the tank, to get a sense of what the roots and rock wall will look like. Sorry that the pics look a bit blurry.




This view from the left side of the tank shows the functionality of the root design. The big hole underneath is where my powerhead will be, mostly hidden from view by the root structure from the front of the tank. That was my goal with the roots, to hide equipment. Another thing that I'll do is paint the side and back of the tank with Drylok/black cement dye, to hide the silicone adhesive and equipment from view.
 
#85 ·
My buddy Nick used Drylok to paint the sides and he said it works great. I was going to buy one of those paint on rubber products. No need now :)

Yesterday afternoon, I had some time to work on the roots. However, when I went downstairs, I remembered that my paintbrushes were all ruined. Also, I opened up my can of Drylok and it was solid as a rock. When I first bought the can a couple years ago, it fell out of my truck, opened up, and spilled white Drylok on my driveway. Apparently, when I put the lid back on, I didn't put it on tight enough, and air got in there. I was also out of the charcoal color cement dye, which is necessary to bring out the deeper nooks and crannies of the work. So, I went to HD and they had everything that I needed in stock.

When I got home, I slapped on the first coat a Drylok, pretty thick too, to make sure that all of the root surface was covered, to seal everything in. Drylok tends to shrink when it dries, I think, because sometimes, small holes in your work tend to open up when it dries and they require a touch up. I only found two of those last night, so I'm really happy about how this coat went on. The roots look pretty good now, as the pink foam is finally covered, but, they aren't the rootsy color that I want. I will add a few new coats of Drylok to add color and try and bring out some realism. I may add a few tricks to do that too, regarding texture. I need to think about how to do that, and if I can pull it off, I'll review the how afterward.

Here is the Drylok that I used. I prefer the Gray. It's important not to get the "extreme" Drylok product because it has mold inhibitors and other chemicals that could be harmful to the tank. This is latex based Drylok. I mixed it with Quikrete charcoal color cement dye. It's easy, just pull out some paint, pour in the liquid dye, and stir it in.


I painted the first coat on thick because I really want to seal everything in to prevent pH issues from happening.


First coat finished, from the front left side.


A close up of the split bark section. It looks much nicer with the pink foam board finally covered up. I'm really happy with how this turned out. Drylok is great because if you have detail carved into your work, it does not fill in the gaps and cover it up. This is the only exposed foam after the grout coating.


Showing the knot and hole. I think it turned out too big, but I can live with it.


More of a left side view.


It's getting there...I can't wait to get home from work and work on it again tonight.
 
#90 ·
My original plan was to have the roots done by this past Sunday. I had a 3 day weekend to work on it, and only managed to work on it on Friday. I slapped on another coat of Drylok, this time, mixed with Brown cement dye. I totally covered up the dark charcoal color, not really planning ahead. But, once you paint it, you either have to do it over or settle with it. I confused myself over the coloration of the roots that I was after.

I had two different approaches for coloring the roots. The first option was to color them as if they were tree roots above water, and let nature take its course in my tank. This would be the darker gray base that I used on the first coat, dabbed with lighter shades of gray, maybe a tint of brown and green here and there. After a while, option one, with fish tank life, like algae and bacteria, would grow on the roots and eventually bring some realism to them. The other option was to color the roots up like you'd see them underwater in the wild, simulating algae, bacteria and other life on them already. This would be the brown base, colored up with lighter shades of brown. My first coat was option one, but, instead of dabbing on the grays, I coated the second coat, not thinking, like option 2. Fortunately, the fix is easy. Either I re-coat for option one, or keep it as it is and proceed with option two.

Option one would look like the roots that are above water, and option two would look like the underwater roots, both seen in these pics that I took the other day:



Here's the brown coat, option 2, started, that I will complete. I figured that the additional algae and other life in the tank will take it from being sort of lifelike to lifelike. It will look more like nature sooner than option one.

Below are the roots after the base brown coat. On the split root, I messed up and mixed up a funky mustard brown color. I wanted a lighter shade of brown, but, it didn't work out. I will fix it on the next painting application.



The underneath/back side of the roots:
 
#92 ·
Thank you Kipnlilo!

I'm almost finished with the roots! I only have one more coat of paint to dab on there. I brushed on a thick coat of dark brown last week, and this yesterday, dabbed on a lighter color of brown with the sponge. I will dab on an even lighter coat this weekend to finish up the painting.

Here's a pic taken when I was finished, no flash.


It was hard to see any detail in this picture under the room lighting. So, I took one using the flash on my phone.


I liked how the flash shows more detail, so I put the roots in the tank. Then, I brought in the two shop lights and put them over my tank and lit up the background and snapped these pics. First, full tank shot:


Zoomed in on the roots:


Looking in from the right front view of the tank:


I'm pretty happy with how they turned out so far. Next steps after the last coat will be another dabbed on coat of paint for highlighting. Then, I may seal it in with tile adhesive...I'm not sure yet. I'm a little concerned about durability, because I had some cracking and a soft spot. I don't understand why that happened, but maybe the tile adhesive will cinch things up. I have some silicone mess to scrape off the right side of the tank too.

I am planning on going fishing this weekend, and my plan is to gather some rocks and gravel from the river. If I can do that, then I can start running the tank! I need to purchase lighting for this tank too, so I will do that soon. I want an LED fixture that can grow plants. It will be nice to get the 75g stream tank done so I can focus on finishing my oyster reef build.
 
#95 ·
News on the 75g stream tank: First, I went on a fishing trip this past Saturday, and successfully collected enough river rock for my tank. I need to get some sand and some smaller rocks and gravel still, maybe this weekend. I decided on the new lighting fixture that I want, a Fluval Planted 3.0. It should be perfect for this tank. I will order this light fixture very soon.

Last night, I dabbed on the last coat of paint with a sponge to give it some highlights of a lighter color. I think it turned out OK. It doesn't look that much different than the last time I took pics. I put my shop lights over the tank and took a few pics at different angles.

Full tank shot:


From the left front corner of the tank:


Close up of the roots in front:


Right front corner of the tank view:


Basically, my roots and background are almost done. If it wasn't for the next step, that I just decided to do, that will happen as soon as I can. I decided to seal in and protect my work on the background and roots with a clear coat epoxy called Polygem 1319. I've read good things about it. For example, it looks not so great without water in the tank, that it shows a shiny coat when dry, but in the water the shiny coat disappears and you can't tell that there is epoxy on there. It dries hard as a rock, seals everything in underneath, and is very durable. It's used by public aquariums and museums. So, I ordered a quart of it, and it should arrive in a few days, hopefully in time for the weekend. Anyone ever use this stuff before?

I figured that I put so much time and effort into this stuff, that it would be a shame to ruin it. The Drylok is great, but, all it takes is a scrape from some sort of cleaning tool to chip off some foam or Drylok and you have an ugly pink spot. The rock wall background and roots are actually pretty fragile. I'm sure that I could easily chip off the grout, so this epoxy will help the roots too. So, for now, another week, probably.
 
#96 ·
After doing some research, I probably will not use the Polygem 1319 on my rock wall. Apparently, it melts foam. I don't know what will happen with foam covered in Drylok. I may try a test piece, but, this stuff apparently gets very hot. I don't want to chance ruining the look of the rock wall.

As for the roots, I think that I will test it on a small section of the roots near the bottom that will be covered in rocks and substrate anyway. I can always add more grout and paint it again. Since the roots are covered in both Drylok and grout, maybe the heat won't be an issue. If it works, then I'll test a small section of the knob. If all goes well with the tests, then I'll apply it to the entire structure.

I originally wanted something to firm up the grout anyway. I thought that maybe it would be a good thing to do with the foam. After researching, there aren't many options for clear coating over already painted foam. There are plenty of coatings that are white that you have to paint, but, for me, that isn't an option.
 
#99 ·
I talked to the Dave at Polygem, nice guy. He said that the heat wouldn't be a problem because you apply a thin coat, so any heat generated should be minimal.

Since I don't have to worry about mixing colors, he said that when using the clear coat, it would be better to mix up small batches and apply it in sections at a time, especially with the roots where it might take more time to apply because of the shape complexity. And, he agreed with me about testing it first.

As it turns out, they have a better product, 1618, that cures much faster. Next time, I'll get that instead...same price. There is a possibility that I might need more for this project. He answered all of my questions and took the time to really explain things. In a nutshell, great customer service.
 
#101 ·
Thanks Kipnlilo. I already ordered and received the Polygem 1319. I'm pretty confident that it be OK. Depending on the results, if I need more clear coat, I may consider the Pond Armor if things don't go well. If my tests go well, and I use all of it up, I might get their better product though. I'll post results. At least everyone will know if there is another product out there that will do the job or not in case Pond Armor goes out of business or something. If the tests fail, then I'll purchase the Pond Armor. Thanks for the recommendation everyone.
 
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