Concerns on a DIY background

[jnunn]

I am setting up an 80 gl tank in my living room and I am considering making a DIY background using the typical sculpted foam covered with a thin concrete mixture.
I have concerns that the concrete will leach chemicals in to the water column even after the concrete has cured.
I would appreciate any and all comments.

Jim

[Aquinoobie16]

From the research I've done on this subject you just have to let it soak for a few days while doing water changes every day and you should be fine my main worry would be chemicals but crumbling of the concrete which can happen over time

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[PinkRasbora]

After the cement, cant you use a marine grade sealant as a coating over the top?

[Diana]

Use the potable water product made by Sika.
It is a concrete sort of product, and you can use concrete coloring materials, but it is sold with a gallon of liquid that locks up the minerals that would otherwise affect the water.

I would still age it, though. Plenty of water changes, and test the water. When the GH, KH, pH and TDS stay stable, it is ready to use. After that there may be a very slow release of minerals into the water, but not much at all.

Perhaps a marine grade of sealant would help. I have always been concerned about plecos rasping off such a material.

[thepotoo]

I have put together two backgrounds on different tanks (38 and 110 gallon) with Quickrete concrete + acrylic fortifier compound. Both times I let the tank sit full of water and empty of livestock for 2 weeks before doing two 100% water changes. The pH got up to 11 after the first day, but these water changes brought it back down to 7. Afterwards, I gave it another week just to be safe, but then the concrete seems to be completely inert. (One of the tanks is a mbuna tank and I was hoping the concrete would help buffer the water to pH 8 like crushed coral does, but it really doesn't do anything.)

Check your pH. If it's in a safe range, I think it's safe to assume that anything else leeching out of the concrete is safe, too.

[hingedthinker]

I am building a layered foam / concrete background for my 125G reef tank now (in-process). There is a great set of videos on youtube on this very subject by a DIY-er. He initially used a food grade sealant, but then switched to the dry lock product for durability.

Based on my research, you should set the finished product in water with weekly water changes and a powerhead until pH settles...which could take 1-2 months or more.

I am using a blend of quickrete and a compound from marco rocks for my wall including live rock...

[shrimpNewbie]

Use a marine grade sealant. Best way to do it, thin layers and make sure you sand the sealant late after full cure and repeat several times still completely sealed and you don't have. Glossy look.

[driftwoodhunter]

Don't bother with concrete! I used Drylock for my two 29g 3D background builds - it was very, very easy. You should be able to see the journal I did by clicking on the 29 twin tanks in my signature. I'm cooking dinner now or I'd post more...

[driftwoodhunter]

Ok, I'm back.
The things I like about Drylock include that it's for potable water (so it's safe), it dries quickly and needs no curing time, you can tint it with powder or liquid concrete colorants, it's nearly odorless, and it's so easy to apply. I found out about it on the Cichlid Forums, under the DIY forum.

http://cichlid-forum.com/phpBB/viewforum.php?f=30

There are a bunch of projects there, some with concrete, some with Drylock - it's worth a look! btw, the backgrounds I did for the 29g tanks have a light patina of algae or something, and it really adds to the natural effect I was hoping for. They have held up perfectly.

[hingedthinker]

Originally Posted by driftwoodhunter

Don't bother with concrete! I used Drylock for my two 29g 3D background builds - it was very, very easy. You should be able to see the journal I did by clicking on the 29 twin tanks in my signature. I'm cooking dinner now or I'd post more...

For a reef tank, you have to add structure to the foam. Dry-lock wouldn't last long in salt water with a soft foam background with worms, coral, etc chewing it up. ;-)

[jnunn]

Thank you one and all.

It sounds like a potable water product would be my best choice.

Photos may follow when finished.

Jim Nunn

[driftwoodhunter]

Originally Posted by hingedthinker

For a reef tank, you have to add structure to the foam. Dry-lock wouldn't last long in salt water with a soft foam background with worms, coral, etc chewing it up. ;-)

But this is for a freshwater tank, yes? I know backgrounds need to be different for salt, but why go through so much extra work if the livestock doesn't require it? Oh well, lots of choices for the OP to sift through - that's part of the fun. lol

[hingedthinker]

Originally Posted by driftwoodhunter

But this is for a freshwater tank, yes? I know backgrounds need to be different for salt, but why go through so much extra work if the livestock doesn't require it? Oh well, lots of choices for the OP to sift through - that's part of the fun. lol

Sure go for it, you have done your homework. Good luck.


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[the_deeb]

Originally Posted by driftwoodhunter

Don't bother with concrete! I used Drylock...

I second this. There's no need for concrete - just use latex-based Drylok. You can tint it with cement pigments to get the color you want. Here's an example of a recent Drylok-only background and rockscape that I made for my current 65g tank:



I've built a number of DIY background and have found that the Drylok method has has a number of advantages over concrete: the main one is that it doesn't alter your water hardness. Another big one is that it doesn't crack. I've found that a thin coating of concrete on a DIY background is brittle so it's really prone to cracking and then chipping off in large flakes if it gets damaged. If you're using concrete to add structure, as suggested by Hingedthinker, you need to use a lot of it.

The cured Drylok layer remains somewhat flexible, so if something ends up hitting or piercing the coating it may leave a hole but it doesn't chip off. If you use several thick coatings (I used about 3 or 4 for the background pictured above) it forms quite a tough layer.

Hope that helps.

[driftwoodhunter]

the_deeb, that is the most beautiful DIY background I've ever seen, and I looked at tons while learning how to make one!!