75 Gallon US Native Tank with DIY Foam/Drylok Background

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75 Gallon US Native Tank with DIY Foam/Drylok Background

Postby Chasmodes » Tue Feb 14, 2017 4:00 pm

I want to start off first by thanking the pioneers in this hobby that have shared their experience and methods for DIY projects like this, on this website, FB and other sites as well. I've learned a lot and have considered every option until finally making decisions to go forward.

The concept is a US Native local biotope tank housing darters, minnows and shiners. My goal is to mimic and undercut bank with an eddy that flows against a shale rock face. I am building this currently outside of the tank in four sections so that I can install it into the tank easily (due to the center brace on the top frame of the tank).

As far as the background build, it's kind of been a learn as I go type of thing. This is still a work in progress. I basically created a tank frame out of hobby foam board to match the dimensions of my tank, then carved a piece of board at at time, starting with section one on the right side working left. I used Gorilla Glue to bond each layer together. I also used wooden skewers to help me visualize and keep things in place until I liked what I saw, then replaced them with plastic popsicle sticks cut to fit, then glued them in place. This was to make the structure more solid and workable outside of the aquarium. Also, as a note, Gorilla or Duct tape make for good temporary ways to hold things together.

My goal with the rock face was to mimic shale that wasn't in a horizontal plane. Attempting this has challenges with keeping the structure consistent and together, so that's why I did it a layer at a time.

My initial carving is in the pic below. I used a similar technique to one that I saw on another forum, using the existing grain of the foam board in my favor, chipping away to get the shale rock effect. One key is to eliminate straight lines, 90 degree shapes, etc. because they're relatively rare in natural rock.

This is actually the 2nd section. I was using my tank frame for support to get a feel for what it would look like.
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After that, I decided to work on sections 1 and 2 at the same time:
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I also did a lot of experimenting along the way. I tried to see what effect a heat gun would have on my work (test pieces). I like the look, but I later decided not to use it for this purpose. Maybe I will later when I work on section 4:
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This picture shows the plastic popsicle sticks that I glued in for extra structural support:
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This pic shows how Gorilla Glue is applied, and how I've incorporated the popsicle sticks. Gorilla Glue expands, so keep that in mind (not as much is needed as other glues), and weighing it down helps to keep the gaps between your faux shale layers from expanding too much:
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Sometimes accidental discoveries lead to experimentation. Here is a picture after I used a heavy cement block from another DYI project for weight to keep the Gorilla Glue from expanding that left a cool impression that looks more like a rock face than the actual foam board that I started with. It gave a rock like texture without much effort:
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So, I got to thinking, what else can I do? Around my area, you can find different fossils in the rocks in some of our streams, like brachiopods, crinoids, trace fossils (like worm burrows), bryozoans, coral, and other bivalves. Some things around the house might allow you to create your own fossils. Springs bend and make for nice crinoid stems (large screws are OK for making pieces of stems), sea shells for bivalves (and brachiopods if you have them, otherwise being creative with clams can imitate them), coral for coral and bryozoans, and worm trails for...er...worm trails!
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Drylok, from what I hear, and we will see, will allow you to capture a pretty good amount of detail. So be creative! Here are some faux fossil examples:
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Last edited by Chasmodes on Tue Feb 14, 2017 5:15 pm, edited 1 time in total.
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Re: 75 Gallon US Native Tank with DIY Foam/Drylok Background

Postby Chasmodes » Tue Feb 14, 2017 4:20 pm

Here is a picture of my work after almost completing the carving of sections one and two. Next to it is a picture of the shale rock face and texture that I found on-line that inspired me for this project:
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As I said before, constructing layers like this presents a set of challenges, like overall background thickness, buoyancy, and structural stability. Here is a side view to show the gaps in the structure that I have to deal with:
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After carving most all of the rock work in sections 1, 2 and 3, here the background is shown fitted in the 75 gallon tank. I also decided to add a layer on the bottom so the rock face would fit flush to the bottom of the tank:
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After that last pic, for each section, I used Gorilla Glue and the popsicle sticks to attach the rock face to the foam tank structure (the part that will be ultimately glued to the tank glass). I had to be careful to make sure that the sections fit tightly together, so that the seams between them looked like natural fissures within the rock. I also added some cracks. Any sharp object will do, but the wood skewers worked great for carving those out.

The next step was to fill in the gaps. I was concerned that an all foam background would be too buoyant, so I stuffed river stones in the gaps, then filled the gaps with Great Stuff expanding spray foam. I used the regular foam for this purpose. It bonded everything together nice and tight.
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After that, I had to do some carving and trimming of the foam to get it to fit again. After reviewing my work, I noticed that the gap between the fissure of sections 1 and 2 was too wide, and the foam left huge holes inside. I didn't want fish trapped in there, so I spray foamed them together (pic below). That's where I am at today. My next challenge is to cut them apart again so I can make sure that they fit inside the tank. At least I know that they'll fit snugly together. I still have some trimming along the fissure to make it look like a crack again and will get to that tonight.
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My next steps after that will be to make my undercut root bank (section 4) and finish section 3. I'll make the roots out of PVC pipe, foam tubing, stainless steel wire, plastic air tubing, rope, and twine. I'll make a little more foam shale chunks and try to imitate a mud bank below the roots, partially covering the rock structure to blend it. I am aiming to make the roots to look like those of a sycamore tree.

After I do all of that, then I'll use various coats of Drylok mixed with cement pigment to paint the rock face and roots. If all of it fits after that, then I'll install it with glue into the tank. I'm debating in my mind how best to do that. The spray foam bonds well to everything, but it's very messy and would require trimming away excess and also painting inside the tank. Silicone is an option too, but, I'm not too keen about using it. When I first started working with the foam boards, I tried using silicone to glue and carve them, and I couldn't get what I wanted, and they pulled apart easily. But, it would be easier to install and remove the background if I have to. Gorilla Glue is an option, but I'd have to test it between foam and glass to see what kind of bond that I'd get.

By the way, I tested Gorilla Glue on extra chunks of foam board and it is impossible to separate the foam boards once the glue cures without breaking the foam. And, I did a test using water (as recommended by the manufacturer) and not using water, same result. The foam breaks first and the glue stays glued to the foam.
Last edited by Chasmodes on Tue Feb 14, 2017 5:20 pm, edited 1 time in total.
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Re: 75 Gallon US Native Tank with DIY Foam/Drylok Background

Postby Chasmodes » Tue Feb 14, 2017 4:35 pm

Some other things and tips:

Expanding spray foam is very messy. It's tough to remove from your skin. Wear rubber gloves and eye protection. If it gets on your skin, WD40 or acetone should make it easier to remove and clean, but after it the foam dries, that doesn't work, so catch it early.

Carving foam the way that I did will lead to a sense of excitement when things start looking like you want them (at least it did for me). You'll get so fired up that you will want to work quicker. After a trip to the emergency room on Christmas Eve where I got four stitches, I'm now ready to advise that you work slow and safe. I wound up buying a Rapala filet glove to protect my other hand. And I always make sure that each cut is in a safe direction.

Tools used:
-for carving, a sharp butcher knife, snap blade utility knife, exacto knife, saw (at first...the utility knife is awesome and replaced my need for the saw)
-anything for weight when gluing
-wire brushes (great for texture or roughing up surfaces prior to gluing)
-rule and measuring tape
-sharpies for marking cuts and shapes that you want
-cheap longnose pliers for cutting skewers, popsicle sticks, pulling out dried or semi dry glue or spray foam (make sure that if you use them for that, that you're willing to part with them after you're done with your project, or only use them for stuff like this, because they will be ruined for about any other purpose).
-anything that can scrape to make texture
-wood skewers, not only for helping to hold foam boards in place, but also for actual sculpting. I used them also for starting holes for the popsicle sticks
-a drill bit. I learned the hard way that using a drill on foam is pointless and not accurate. Just use the bit to drill your hole by hand. it's much easier and you'll get a better hole with tons more control.
-scrap foam board for structure and for spreading glue...why waste anything?
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More tools used later will be posted as I proceed with my project.

Thanks for following!
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Re: 75 Gallon US Native Tank with DIY Foam/Drylok Background

Postby Chasmodes » Wed Feb 15, 2017 8:12 am

I was worried that I messed it up, but after cleaning it up a but, a little more carving, and then cutting sections 1 & 2 to separate them, I'm fairly pleased with the outcome. I had used the plastic popsicle sticks to temporarily join the two sections while I worked with them, and eventually glued them into place. Prior to using the Great Stuff foam, I cut them off. But, I couldn't separate the two sections exactly as I had before, so I just cut along the fissure. The only problem that I had was when I encountered the old popsicle stick. So, I had to use a hack saw blade to cut through them to finally separate the two section. As you can see, Great Stuff does indeed fill gaps:
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After cleaning and some detailing, it fits much better and looks pretty good, especially when viewing from the center or left:
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I checked for the fit in the tank and everything fit perfectly, both together and in the tank, view from the center/left of the tank:
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Below is the view from the right side of the tank. I'm not as happy about this view because IMO the fissure looks man made, so I think I need to do a little more detailing/carving to get it to look more random. It's not bad, and I know that I'm being picky, but now is the time to get it right:
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I can't wait to get home from work every day to work on this thing. It's kind of fun now. I still need to carve and detail the third section, and I think that I'll do the same thing as far as filling the gaps between the sections, but I won't use so much foam and will spray the back panel more so that it doesn't protrude through the fissure. It should be much easier to cut too, because there are no glued popsicle sticks in between these sections:.

Then, after that, it's on to finishing the left side with the roots and mud bank.

Thanks for following!
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Re: 75 Gallon US Native Tank with DIY Foam/Drylok Background

Postby Chasmodes » Thu Feb 16, 2017 7:50 am

One of my biggest concerns is that foam is so buoyant. I've read about other aquarist's accounts of horror stories about foam backgrounds separating from the tank glass and rocket out of the water, even breaking glass tops and lights. I'm not worried about breaking equipment, but I don't want my time, materials, efforts and money wasted on a failed project.

I want this to be a permanent background to the tank. So, I'm running a couple of experiments. I don't have any more Great Stuff and I don't want to waste my pond foam for this, but Gorilla Glue pretty much bonds the same way.

Experiment 1: Last night, I roughed one scrap piece of foam board a little, and didn't rough up the other test piece, and glued them both to the glass of a broken riker mount. The bonding strength was pretty good this morning. I had to put some effort into separating it from the glass (for fear of breaking the glass too). I was able to pull the foam away from the glue in both cases, but the glue remained bonded to the glass and did not come off! There wasn't much difference between the two tests, pretty much the same result.

Experiment 2: This morning, I roughed up two pieces of foam board quite a bit more to get more gaps and such for the glue to hold, and with one piece, used GG to glue to the glass, and the other I used silicone. I will give it 24 hours before trying to remove each from the glass. We will see which one provides the best bonding strength, and that will be what I go with. I leaning to not to using GS because it's too messy and I don't want to do any in tank carving or painting of the background due to foam expansion.
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Re: 75 Gallon US Native Tank with DIY Foam/Drylok Background

Postby Chasmodes » Fri Feb 17, 2017 7:55 am

My experiment results: The Gorilla Glue separated from the glass, not easily, but easier than I thought it would. It's interesting that the thinner layer used in the first experiment stuck better to the glass than the more liberal amount applied this time. With the same, or even more effort, I could not separate the siliconed foam from the glass. So, I'm going with silicone to secure the structures to the tank. I'm a bit relieved too, because it will look cleaner and I won't have to do any in tank refinishing of any of the background sections.
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Views from the left and right:
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I experimented with using a large wire brush on a scrap piece of foam board, looking for another way to apply texture. I was thinking about applying it to the roots or wood, but I might even do this with some of the rock. It's too cool not to use. Scraping provides a layering texture, hammering provides a porous texture. The brush will also be the best way to rough up the back of the background before applying the silicone. I will also create some holes to fill with silicone that will help to secure it all in place.
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I'm ready to convert this stuff to roots for the left side. They're expecting nice weather this weekend, so I'll be able to use my heat gun to start bending PVC pipe into the shapes that I want. I read somewhere that doing that indoors isn't a good idea because of toxic fumes. Likewise, I have a little more spray foam work to do and I'll do that outside as well.
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Why do I experiment and not just trust everything that I read? I guess I have to see it before I believe it, especially this late in the game when I could risk it all being ruined. It also doesn't hurt to make sure that what I think will work will actually work. I had faith in the Gorilla Glue or foam for bonding to the glass, and maybe some people have had positive experiences with that. But, I'm searching for the best options. Up until now, my hunches all worked out OK. But this time, my experiment proved me wrong.

Thanks for following! ;)
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Re: 75 Gallon US Native Tank with DIY Foam/Drylok Background

Postby Chasmodes » Sun Feb 19, 2017 10:12 pm

I haven't done any aquascaping the past couple days because now is the time to think about my equipment placement, to add that element into my design to build around. So, I created a place to put my Fluval 405 intake. I built a compartment with a strainer to allow me to place the intake into, and be able to remove it for maintenance and cleaning. I have to paint it still. I will eventually have the intake completely hidden from view, except from the right side of the tank. I also built a spray bar for the cannister filter on the left side of the tank for surface current to mimic stream current going over the soon to be created roots.

Showing how my intake fits into the structure:
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Left side view of the spray bar and intake compartment and my filter (below). The filter will be under the tank. Once I get the tank up and running, I may build a facade to hide all of the equipment. Very little of the equipment will be visible in the tank when I'm done. All of the PVC will be painted black, by the way.
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Right side view of the tank. Some of the intake may be visible from this view when I'm done, but not easily seen. It will be hidden by faux rock work, faux roots, and stream bank.
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Now that I've got my basic in-tank structure in place, I'm ready to start creating roots and finish the stream bank. I'll glue the spray bar together later once I start filling the tank and put the filter into action.

Thanks for following!
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Re: 75 Gallon US Native Tank with DIY Foam/Drylok Background

Postby gminor » Mon Feb 20, 2017 11:58 am

Chasmodes,
I have to say many aspects of how you're working your background project are impressive. Your knowledge and application of aquatic biology in your design, your methods of creating the very natural looking shale rock shapes and textures (which is not easy to do) and your overall test and application strategies.

As far as anchoring your background, I'm glad you're going with silicone. I've done a dozen backgrounds up to a 90 gallon size using 100% silicone and never had an issue. You have the right idea about more texture/surface area on the anchor surfaces.

We're looking forward to updates as your project develops further. Thanks so much for sharing!
Glenn
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Re: 75 Gallon US Native Tank with DIY Foam/Drylok Background

Postby Chasmodes » Mon Feb 20, 2017 1:24 pm

Thank you Glenn!

I'll keep posting throughout the build, and follow up after the tank is up and running. One question that people always ask on forums and don't seem to get many answers are about how these tanks are doing years down the road, and specifically about the durability of our 3D backgrounds and other things that we make. Hopefully, I can provide those answers later.
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Re: 75 Gallon US Native Tank with DIY Foam/Drylok Background

Postby Chasmodes » Wed Feb 22, 2017 11:55 am

Updates:

On Monday, I painted the cpvc and pvc stuff that would have been exposed to view. I also filled in the gaps and foamed sections 2 and 3 together.

On Tuesday, I had my first setback: I cut sections apart 2 and 3 along the fissure. It was tougher than I thought to do for a couple reasons:

1 - I found some yellow goo - uncured Great Stuff. It doesn't cut well. So far, this is the first time that I've found this. I poked a bunch of holes into it and all around it deep into both sections. I checked on it today and it all seems fully cured. However, I poked a few more holes with a skewer and found some more. I think that the solution is to get some air (and maybe water) in there to speed up the curing of the thicker areas. If you remember, it's not all foam, but a good many stones are in there too. So, I'm not that worried about it. I'll keep poking holes until the skewers stop being sticky. I think that I'm going to go back, just in case, and do the same thing for section one.

2 - When cutting the fissure between the sections, I had some trouble using my knives. So, I pulled out the heavy duty equipment, a saw. Should do the trick right? It was in an area where I had a plastic rod. That is what I thought it was, and the saw should have taken care of it. But, after a couple minutes of sawing and no progress, I realized what it was. Did you know that it is really tough for a hand saw to cut through a river stone?
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