What should I use for a water-tight seal from acrylic to plastic?

[Zoe’s Reef]

Hi all! I'm currently attempting to do a small repair on an AIO acrylic tank. My goal is to re-seal the area in the picture, connecting the plastic return nozzle to the acrylic side of the tank. It needs to be a completely water-tight seal. I'm interested in using something with the same thickness as silicone, but after research I found that silicone doesn't work well with acrylic or plastic. Does this mean that silicone won't create a water-tight seal with acrylic? Or simply that it is not strong enough to hold an acrylic tank together? I'm not necessarily looking for strength, but just something that'll be water-tight.

If silicone is definitely not the way to go, how would you create a seal that sticks to both plastic and silicone? What brand would you use?

Thank you in advance! I hope this is the right place to post this.

 

[vetteguy53081]

2 part marine epoxy Or aquarium sealant. Epoxy will be stronger

 

[Brewtoszek]

Hi all! I'm currently attempting to do a small repair on an AIO acrylic tank. My goal is to re-seal the area in the picture, connecting the plastic return nozzle to the acrylic side of the tank. It needs to be a completely water-tight seal. I'm interested in using something with the same thickness as silicone, but after research I found that silicone doesn't work well with acrylic or plastic. Does this mean that silicone won't create a water-tight seal with acrylic? Or simply that it is not strong enough to hold an acrylic tank together? I'm not necessarily looking for strength, but just something that'll be water-tight.

If silicone is definitely not the way to go, how would you create a seal that sticks to both plastic and silicone? What brand would you use?

Thank you in advance! I hope this is the right place to post this.

When you say stick to both plastic and silicone are you asking if you can seal over existing(damaged) silicone with a different material? If so I would not try to do that, if there is existing silicone in that area id try to get all of it off, and maybe even scuff the surface on both sides a little, will help with bonding epoxy if your going that route and also clean off the existing silicone . It’s tough to get things to stick to silicone, so I’d worry about using somthing over it, especially if you need water tight seal.

 

[HuduVudu]

Does this mean that silicone won't create a water-tight seal with acrylic?

Correct.

Or simply that it is not strong enough to hold an acrylic tank together?

Acrylic to acrylic bonds use acrylic cement. It is strong water tight bond.

The manufacturer of your tank did not think that the bond there should shold be water tight else the would not have used silicone, or they didn't care.

Just for reference what you are calling plastic is actually likely PVC and this connection is notoriously difficult to make permanant. I have made this connection with a resin epoxy (they don't make it anymore), but I am sure that there are epoxies on the market that will do this. Just know that working with these isn't very astheticly pleasing and you will need to work to ensure a clean look. Also note the bond is permenant. Just things to consider.

Good luck this is a less than fun thing to deal with especially if you have an aquarium that is already set up.

 

[Zoe’s Reef]

2 part marine epoxy Or aquarium sealant. Epoxy will be stronger

Thank you!

 

[Zoe’s Reef]

When you say stick to both plastic and silicone are you asking if you can seal over existing(damaged) silicone with a different material? If so I would not try to do that, if there is existing silicone in that area id try to get all of it off, and maybe even scuff the surface on both sides a little, will help with bonding epoxy if your going that route and also clean off the existing silicone . It’s tough to get things to stick to silicone, so I’d worry about using somthing over it, especially if you need water tight seal.

I apologize, I mistyped there. I meant stick to both plastic and acrylic. So far my plan is looking like I'll scrape off all of the silicone, then use a two part marine epoxy.

 

[terraincognita]

Correct.


Acrylic to acrylic bonds use acrylic cement. It is strong water tight bond.

The manufacturer of your tank did not think that the bond there should shold be water tight else the would not have used silicone, or they didn't care.

Just for reference what you are calling plastic is actually likely PVC and this connection is notoriously difficult to make permanant. I have made this connection with a resin epoxy (they don't make it anymore), but I am sure that there are epoxies on the market that will do this. Just know that working with these isn't very astheticly pleasing and you will need to work to ensure a clean look. Also note the bond is permenant. Just things to consider.

Good luck this is a less than fun thing to deal with especially if you have an aquarium that is already set up.

On that note I never make a water tight seal around my return pump entrace.

If you ever want to change those nozzles or upgrade your pumps, it potentially will make it much harder.

Finding a rubber washer and a threaded nozzle adapter is generally the route most people go with something like that.

 

[Zoe’s Reef]

Correct.


Acrylic to acrylic bonds use acrylic cement. It is strong water tight bond.

The manufacturer of your tank did not think that the bond there should shold be water tight else the would not have used silicone, or they didn't care.

Just for reference what you are calling plastic is actually likely PVC and this connection is notoriously difficult to make permanant. I have made this connection with a resin epoxy (they don't make it anymore), but I am sure that there are epoxies on the market that will do this. Just know that working with these isn't very astheticly pleasing and you will need to work to ensure a clean look. Also note the bond is permenant. Just things to consider.

Good luck this is a less than fun thing to deal with especially if you have an aquarium that is already set up.

Thank you! Luckily, it's only a 5g... but I had it set-up and it started leaking (definitely needs to be a water tight seal) so I took it apart and now we're here. I'm planning on doing a two part marine epoxy and scraping off the silicone underneath. It very possibly could be PVC but this is a cheap little tank, so it's also very likely it's just cheap plastic. Thank you for your help!

 

[Zoe’s Reef]

On that note I never make a water tight seal around my return pump entrace.

If you ever want to change those nozzles or upgrade your pumps, it potentially will make it much harder.

Finding a rubber washer and a threaded nozzle adapter is generally the route most people go with something like that.

This is a little 5g tank, and the way that it was built is if water gets into that chamber behind the nozzle it spills all over the counter. Running up that chamber is a tube that is directly connected to the nozzle, but there's a crack in the silicone that is allowing water to escape behind it. Not really part of the overflow, rather a completely separate chamber that's meant to remain dry in this AIO. I do appreciate the advice though!

 

[terraincognita]

loc line connector - Google Search

Something like this with some rubber washers will still be cheaper and easier and definitely cleaner IMO.

But do what's best for you!

Just saw your reply about crack in the silicone.

Scraping that off completely, and doing something like above might work easier. you can still make a water tight seal.

 

[Zoe’s Reef]

loc line connector - Google Search

Something like this with some rubber washers will still be cheaper and easier and definitely cleaner IMO.

But do what's best for you!

Just saw your reply about crack in the silicone.

Scraping that off completely, and doing something like above might work easier. you can still make a water tight seal.

Thank you! I'll look into that. And this will create a water tight seal? I'm just super paranoid about it leaking again because it was a mess!

 

[Zoe’s Reef]

Is this considered a 2 part marine epoxy that is reef safe and will stick to acrylic?

 

[terraincognita]

Thank you! I'll look into that. And this will create a water tight seal? I'm just super paranoid about it leaking again because it was a mess!

use a crescent wrench to REALLY tighten it. But yes, absolutely you will get a water tight seal. you can find adapters that go from that lockline thread into a a Barb Connector to the tubing.

Or even just using another compound to create a seal between the tubing and the loc-line might be easier and work. It'd be more of a mickey mouse solution.

 

[Zoe’s Reef]

use a crescent wrench to REALLY tighten it. But yes, absolutely you will get a water tight seal. you can find adapters that go from that lockline thread into a a Barb Connector to the tubing.

Thank you! I appreciate it.

 

[terraincognita]

Thank you! I appreciate it.

No problem.

Using an epoxy and fixing the seal will also absolutely 100% work.

But just in my mind now you're depending on that seal to hold forever, where as with just fixing the plumbing connections you could have a forever lasting solve.

 

[Zoe’s Reef]

No problem.

Using an epoxy and fixing the seal will also absolutely 100% work.

But just in my mind now you're depending on that seal to hold forever, where as with just fixing the plumbing connections you could have a forever lasting solve.

That's a very good point. Thank you again!

 

[terraincognita]

Is this considered a 2 part marine epoxy that is reef safe and will stick to acrylic?

This will work.

If you are going to indeed go the epoxy route, any epoxy will stick to acrylic just make sure it's marine safe.

If possible sand it with a low grit sandpaper as well beforehand to give it a bit of an "edge"

If that's not possible then just do the best you can.

 

[vetteguy53081]

On that note I never make a water tight seal around my return pump entrace.

If you ever want to change those nozzles or upgrade your pumps, it potentially will make it much harder.

Finding a rubber washer and a threaded nozzle adapter is generally the route most people go with something like that.

An option is a threaded Bulkhead

 

[Flippers4pups]

@Zoe’s Reef,

Instead of epoxy or silicone, look into Uniseals for this type of application.

 

[Zoe’s Reef]

@Zoe’s Reef,

Instead of epoxy or silicone, look into Uniseals for this type of application.

Thank you! Unfortunately I don't have much access in this tiny 5g tank, so I don't think this will be able to work for me, as cool as it is!