Glueing EDPM pond liners together?

[islander]

Hi. I have a small pond with 2 waterfalls and a lot of rock work etc. I am realizing the actual pond is to small to raise Koi. I have an EDPM liner.

At this point my only option is gluing another liner to it. Will probably only be about 8 linear feet of area I have to glue together.

I have been reading about glues I could possibly use. I Wanted to hear from people that have done this.
Here are The 2 products I've been looking at. I like the idea of a glue instead of a liner tape as it seems like it would work better on an existing liner?

3M 5200 fast cure- I called 3M they told me it would work, but toxic to fish. I am not sure if they say this to be on the safe side or if its toxic once dry? The fish wouldn't be touching the actual glue.

PL brand polyurethane glue from lowes- made for roofing and windows and its apparently fish safe but not sure if the joint lasts under water?

Then there is the tape option if glues dont work, what brand to get and where? I'm guessing not from lowes.

Thanks all I appreciate your help

 

[Stouty109]

Firestone make a Epdm fish safe liner seam tape. I've used many time with no problems. I paid $90 for a 25' kit the last time i bought one. They sell a 10' kit. Kit comes with primer, roller, seam tape, scuff pads and a chalk pen. I personally wouldn't use anything other than the Firestone seam kit. But I wouldn't seam together old liner with new.

 

[Waterbug]

Will probably only be about 8 linear feet of area I have to glue together.

I wouldn't say "only" 8', I'd say that would be a huge seam for a used liner.

I like the idea of a glue instead of a liner tape as it seems like it would work better on an existing liner?

I don't know why but I think everyone, myself included, at first thinks they've thought of a better way of seaming than the product designed for the job. It's a very strange logic we have. I think maybe experience is the only cure.

3M 5200 fast cure- I called 3M they told me it would work, but toxic to fish. I am not sure if they say this to be on the safe side or if its toxic once dry? The fish wouldn't be touching the actual glue.

What "they" told you this would work? They are pulling your leg or don't know what they're talking about.

Cured polyurethane is not toxic to fish.

PL brand polyurethane glue from lowes- made for roofing and windows and its apparently fish safe but not sure if the joint lasts under water?

The issue is the bond the glue makes to the liner. Once filled with water there can be a lot of stress on a liner. Kind of hit and miss whether the stress works to pull a seam apart or clamps it together. Depends how lucky you feel.

Then there is the tape option if glues dont work, what brand to get and where? I'm guessing not from lowes.

Online liner sellers have the seaming tape and instructions.

At this point my only option is gluing another liner to it.

There are other options. Make a new pond with 2 pools, one using your current liner. No seam, just overlap liners or connect with a stream overlapping on both ends. Make the smaller pool the upper pool.

 

[islander]

Thanks guys. Sounds like a Firestone brand seam kit is the way to go to be on the safe side. I like how its a complete kit. And yes, for some reason I was thinking a glue alone would be better than a tape. I think I got that stuck in my head from diy web searches where most people just used glue. must be because it is less money, or quick fix. I def don't want to mess around and want it to last.
More Info for the seam ill be making- my existing liner is only a few months old. And the area I am seaming hasn't been underwater, so no algae growth etc.

 

[Waterbug]

Making a 8' seam never leak even with the proper material will still require proper methods.