Gluing rocks and slate

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I got a crazy idea for my new centerpiece ornament. Not exactly like this, but this is the concept I am going to use (note: not my pic).

SlateOrnament.JPG

I hear GE Silicone 1 is what most people would use to glue the rocks and slate together. Is that true? Are there other gluing agents that are safe? How long do I need to cure it before adding it to the tank?

Thanks for the help!
 

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Yes, silicone is generally what is used. Anything labeled 100% silicone should be fine, you don't need to pay for a brand name. Read the label to make sure there aren't any other additives. Generally, you need to wait 24 hours for it to cure. I usually wait a couple of days just to be sure.

As for alternatives, there is stuff you can buy marketed specifically for aquariums, but that stuff is typically much more expensive than simple silicone caulk. Not worth it, IMO.

And nice ornament, btw :)
 

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If it says anything like "anti-microbial additives" or "anti-fungal ingredients" then that's a major red flag that you should stay away! Yes, you can buy aquarium silicone sealant, but if you prefer regular general use sealant, anything that is 100% is fine.

There is a variety of epoxy products out there that can be used as glues or putties if you want a more solidified adhesive. My personal favorite is Seachem Reef Glue but for something that size I don't think I would use it for the whole thing, maybe only if I were to affix a smaller decoration - a building or figurine for example - on top of the bigger rock structure.

I look forward to hearing/seeing how it turns out! Keep us updated! (I have even actually debated similar but always scrapped the idea because I have been skeptical that I could do so successfully and my fish would leave it in one piece)
 
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So I went to Walmart and picked up this sealant that said on the price tag label it was silicone 1. I don't see it on the bottle nor do I see it say 100% silicone. It's an off brand (the only silicone 1 they had). Think it will work or should I take it back and go to the hardware store and see what they have? Here are the pieces of slate that I'm going to use as well.

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I decided not to risk it and took that sealant back and got the good stuff at the hardware store. Now going to let my river rock and slate sit outside in a bucket of water for a few days and the let it dry out for a few days. Should be able to start building on Monday.

Just a thought.. I have some little pieces of driftwood. What do you think about gluing one of them on one of the slate platforms for my pleco? Would the wood have to be completely dry for it to stick?

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I have glued driftwood to tile and it worked OK. Just make sure that the wood fully sinks on its own before you glue it down, or there will be problems. And yes, the wood should be completely dry.
 
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Okay, If its completely dry, it wouldnt be water logged any more, therefore it wouldnt sink on its own. lol So how does that work? hahaha
 

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Some wood will sink on its own. Others will sink enough. You just dont want the wood pulling up your ornament in the long run.
 
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So this is stage 1 of the construction. Letting it cure before I clean it up and add more to it.

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I decided not to risk it and took that sealant back and got the good stuff at the hardware store. Now going to let my river rock and slate sit outside in a bucket of water for a few days and the let it dry out for a few days. Should be able to start building on Monday.

Just a thought.. I have some little pieces of driftwood. What do you think about gluing one of them on one of the slate platforms for my pleco? Would the wood have to be completely dry for it to stick?

Sent from my SM-G900R4 using Fish Lore Aquarium Fish Forum mobile app
DO NOT use that!!!!!

It says mold resistant!!!!!


The only way to make silicone sealant mold resistant is to add antifungal ingredients.

The "100% silicone" on the label only refers to the adhesive. The first stuff you had was probably what you wanted.
 
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I have seen countless threads recommending to use GE Silicone 1. That is exactly what this is......
 

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I have seen countless threads recommending to use GE Silicone 1. That is exactly what this is......
There are hundreds of different "flavors" of RTV (room temperature vulcanizing) silicone sealants/adhesives.

A label claiming "100% silicone" is no guarantee of safety because the makers are referring only to the main adhesive/sealant. They may still add things (like a fungicide to stop mold) and still call it 100% silicone. They're just trying to make the point that the adhesive itself is 100% silicone. They're not promising that there's nothing else at all in it.

Silicone I versus Silicone II.

Silicone I releases acetic acid when curing. It smells like vinegar. That is what you want (but still no guarantee of aquarium safety).

Silicone II releases ammonia when curing. That is generally deemed bad for an aquarium because we fight so hard to eliminate ammonia from our tanks. If fully cured, it, too, would be just fine, but nobody is that patient, so in practice, silicone II should be avoided for aquarium use lest we poison our fish with the ammonia that it will likely release for quite some time!

Now, you've got Silicone I, and it's said to be "100% Silicone". That's good!

But it also says "Mold Resistant". That's bad!

This is because as RTVs cure, they develop a network of tiny pores. Since silicone RTVs cure by reacting to atmospheric moisture, they couldn't cure if they completely "sealed over" as they cured. Layers deeper inside would never cure because they couldn't receive that atmospheric moisture. So the pores are actually essential for the stuff to cure.

The pores won't allow the RTV to "leak". It's still waterproof. But they are large enough to allow mold to grow down inside of them! This looks nasty in your shower, and cannot be cleaned off because it's actually deep down inside of the RTV. I can post a shot of my shower, assembled long before the "anti mold" stuff came out, to show you how it looks if you'd like.

Anyhow, the mold-resistant stuff contains an anti-fungal ingredient designed to keep the little pores in the RTV from becoming infested with non-removable mold. So it stays looking good for many years. Unfortuntatly, this anti-fungal ingredient may easily leach out into your aquarium, and may be deadly, especially to certain aquarium critters.

So you may get away with it and have no problems, or it may kill your fish immediately, or something in between those two extremes. But this is why "mold-resistant" silicone is not recommended for aquarium use.

You want plain, old, mold-growing Silicone I. That may have been exactly what you had the first time.

This is why it's best to buy silicones that are either explicitly recommended for aquarium use, or are actually labeled as being aquarium-safe. It's a real pain reading all of the fine print on the containers while loitering in the glue aisle of the hardware store, too, isn't it? I have to take my glasses off to see that close, and it takes a lot of time. And the makers are under no requirement to list all of the ingredients anyhow.
 
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Well then give me a link to something that will work and doesnt have the premium price of being designed for aquariums.

And now how am I supposed to get all this silicone off the rocks that I wasted 3 hours doing today?
 

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Sorry. I like what you built. It's a great idea and neat design if you ask me.

And I understand why you're frustrated now, but I can't be responsible for other people's advice, or how someone would interpret it, of course.

Unfortunately, you will not be able to easily remove the silicone now. That's the great thing about good RTV. It really sticks!

You could theoretically sandblast it off once it cures, but I'd just get new pieces and start over.

As for getting aquarium-safe RTV:









I use Amazon for a lot of this sort of thing because finding anything "special" is hard in my relatively small city.

I think the project is very worthwhile, and I would love to see you complete it. I just can't say that the RTV you used will actually be safe. Maybe someone else has some experience with the mold-proof silicone and can offer what happened to them with it. I wouldn't use it myself, though.

If it makes you feel any better, I've often found that projects I completed or almost completed, then had to start over, came out even better than the first time even though I at first felt that I was giving up a lot of work and an excellent design. Heck. This is just a hobby, anyhow. We do it to "kill time". You just get double the time-killing benefit from this project!
 

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I actually would think that one is ok, i looked at it about 2 days ago at the store. I think it's calling itself mold resistant not because it has additives but because it's water proof and therefore won't mold. That's what I took away from my careful label inspection anyway. I ended up not getting it though so I can't tell you if it's safe or not. I looked at 5 different brands of 100% silicone and every one of them said mold resistant and did not give an ingredients list. Good luck to you.

 
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Well its already disassembled and thrown out. I will get the aquarium silicone in the future if I decide to give this project another go. Thanks.
 

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Don't give up. I'd love to see what you finally end up with. It looks great and I suspect the fish would enjoy something like that.

I need to do something like that for a couple of aquariums. I put some floating plants in one of them, and it really made the fish come out more and seem to enjoy more of the aquarium rather than hiding in the back. Something like what you showed would be great, giving a lot of shaded hiding places where they could hang out and explore but feel safe.

Plus, it looks a lot better than the pieces of PVC pipe I've got in there now!!!
 

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I actually would think that one is ok, i looked at it about 2 days ago at the store. I think it's calling itself mold resistant not because it has additives but because it's water proof and therefore won't mold. That's what I took away from my careful label inspection anyway. I ended up not getting it though so I can't tell you if it's safe or not. I looked at 5 different brands of 100% silicone and every one of them said mold resistant and did not give an ingredients list. Good luck to you.
While cured one-part silicone sealants are waterproof, they're not gas or vapor proof. In fact, some products are made with it specifically to take advantage of the fact that it is permeable to gasses while blocking water. It's kind of like Gore-Tex, in a way.

But the micropores that form as it cures provide a habitat for mildew and mold to grow. And you can't get to it with scrubbing or most chemicals. (Perhaps you could gas it with chlorine dioxide or something, but...) So it's impossible to clean off of anything but the top surface. If you have clear silicone without the mold inhibitor added, the mildew and mold will grow inside of it, and be visible, making it look nasty. With the white or colored versions, you can at least scrub it off of the surface and hit it with bleach or hydrogen peroxide to make it look OK for a while. But its still a pain. And with the clear stuff, there's no way to make it look good because the mold is distributed throughout the sealant.

So the manufacturers started making bathroom, shower, and tub caulk with the anti-fungal agents in them and advertising the mold resistance because people who have used the stuff without it will likely never use it again!

Here's a corner of my shower/tub:

image

I think you can see why they make a big deal of the mold-resistance.

The cat hair is something they can't do much about, however!

If I tear all of this out and re-do it, I'll be looking FOR the mold-resistant kind of Silicone sealant, for sure!
 
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