# Suggestions to cover sharp edge



## winzdk (17 Dec 2020)

Hi !

This little sharp seem on a pvc pipe need to be covered because I like my fish alive 
Things I consider:
Glue a small stone on it.
Cover it with silicone (I already have this for another project and it can be applied under water)

Other suggestions ? The problem is, it's in a difficult position - 10 cm inside the tube and 10 cm down and I'm not sure how I would apply the silicone.´or if the glue will harden before getting the stone in place.






Thanks a lot.


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## zozo (17 Dec 2020)

Can you reach it by hand? Then a small piece of wet&dry fine grid sandpaper maybe to polish the edge a bit round.
PVC is very soft and you will be done in half a minute...  It also works to dull sharp edged rocks.

In case you need to use a sealant then you could consider TEC7 ms polymer.





						Tec7 Sealant 310ml | Tec7
					






					tec7.ie
				




It is used to repair leaking  garden ponds and it cures submerged. It's non toxic and solvent free... I've used it succesfully in the past, to fix pieces of hardscape, seal sump tubing and even repaired a leaking tank with it. 

AFAIK silicone does not cure submerged and might be toxic, superglue does instantly cure when it comes into contact with moist...


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## winzdk (17 Dec 2020)

zozo said:


> Can you reach it by hand? Then a small piece of wet&dry fine grid sandpaper maybe to polish the edge a bit round.
> PVC is very soft and you will be done in half a minute...  It also works to dull sharp edged rocks.


The tank is high and I'm the only one in the family with arms long enough but unfortunately that also means my hands are too big 
And I guess the sanded off pvc will be bad for the tank environment 



zozo said:


> In case you need to use a sealant then you could consider TEC7 ms polymer.


That is exactly what I got - I just thought it was called silicone.



zozo said:


> superglue does instantly cure when it comes into contact with moist...


Yea that's was what I was afraid of.

Thank you for the reply.
I might go with the Tec7 then I just need to find a method to apply it - maybe a bit at the end of a stick, like a chopstick.


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## noodlesuk (17 Dec 2020)

It looks to be flashing from the  moulding process, a flap of plastic, rather than a sharp edge. So may not be as risky as it might look?  I'd use the edge of another metal tube, copper etc, like a corer to scrape away the flap of plastic. If you can access it.  Or a blade to scrape it away. This however might mean you have a small flap of plastic then floating around! If you use the blunt edge of a tube, it might be enough to fold the flap flat, out of harms way.


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## winzdk (17 Dec 2020)

noodlesuk said:


> It looks to be flashing from the  moulding process, a flap of plastic, rather than a sharp edge. So may not be as risky as it might look?  I'd use the edge of another metal tube, copper etc, like a corer to scrape away the flap of plastic. If you can access it.  Or a blade to scrape it away. This however might mean you have a small flap of plastic then floating around! If you use the blunt edge of a tube, it might be enough to fold the flap flat, out of harms way.



Thanks, I just checked, unfortunately it's not a soft flap easy to cut off. I just tried the Tec7 with no luck, it keep sticking to the stick i'm trying to use.
And the big challenge is, I have to rely on someone else to guide me, because I can only reach it from above and you can only see what's going on from the side/horizontal tube, so I'm in the blind trying to attach the Tec7. And when that someone is terrible at guiding, well it's not easy 
I guess I could try fill the "floor" of the tube with a layer of small 1 cm rocks to cover it.


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## Hufsa (17 Dec 2020)

I dont really understand what im looking at in the pic, but is wedging a piece of filter sponge in there an option?


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## winzdk (17 Dec 2020)

Hufsa said:


> I dont really understand what im looking at in the pic, but is wedging a piece of filter sponge in there an option?


I don't blame you, as it's kind of a unique feature (will post pictures when the project is a bit further).
But basically it's a 8 cm diameter pvc pipe with a 90 degree bend going up vertically burried under the substrate, that's going to act as a "swim through" cave. 
I was also thinking about a small piece of filter sponge, but it will have to be glued on, but the glue hardens too quick.


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## not called Bob (17 Dec 2020)

PU18 or milliput would cure underwater if you can reach, 

I can’t work out where im looking in relation to access if im honest


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## winzdk (18 Dec 2020)

not called Bob said:


> PU18 or milliput would cure underwater if you can reach,


Thanks, I will have a look at that.



not called Bob said:


> I can’t work out where im looking in relation to access if im honest


You are looking inside the horizontal tube and the light is comming through the vertical tube from above.
And the horizontal tube is too close to the front glass to get access from there.

For size comparison, the soil in the tube is Tropica Soil.


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## winzdk (18 Dec 2020)

Overview for clarification 





I'm hoping the edge of the top tube will be covered by the MC


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## noodlesuk (18 Dec 2020)

Ahh see what you mean now, how difficult access is. nice design, is it some sort of fish tunnel? 

Do you think the fish might be able to avoid the edge, like they do with other edges on the rock etc, just wonder how much of a risk it is?  As you mentioned before, maybe place a small pebble/stone as close to the edge as possible, like a little warning road cone!


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## winzdk (18 Dec 2020)

noodlesuk said:


> Ahh see what you mean now, how difficult access is. nice design, is it some sort of fish tunnel?


Thanks yea I'm trying to do something unique or a little out of the box, there is also a few other things in the tank so far that I haven't seen anywhere else. A fish tunnel  was exactly the idea   Are they actually going to swim through it, I don't know but it's still fun 



noodlesuk said:


> Do you think the fish might be able to avoid the edge, like they do with other edges on the rock etc, just wonder how much of a risk it is?


I am not sure I just want to play it safe.  I'm thinking the Ansistricus probably want to dwell in there.



noodlesuk said:


> As you mentioned before, maybe place a small pebble/stone as close to the edge as possible, like a little warning road cone!


That's a very good idea and probably what I'm gonna end up with.


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## not called Bob (18 Dec 2020)

Is it just a 90 degree bit of pipe?  Can you do a brief excavation at waterchange time and take off the offending bit?


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## winzdk (18 Dec 2020)

not called Bob said:


> Is it just a 90 degree bit of pipe? Can you do a brief excavation at waterchange time and take off the offending bit?


It's a straight piece about 12 cm long and a bend connected to it (you can see the connection in the first picture).



not called Bob said:


> Can you do a brief excavation at waterchange time and take off the offending bit?


I can't take the pipe up, I would have to redo a lot and replant the MC. 
I could try the Tec7 again, but instead of a stick I will use a finger, if I can get my hand down there or I can TRY ask the wife 
Otherwise I'll just go with the warning road cone stone


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