Gold Label Underwater Sealant, 290 ml, Black

Fabulous to work with, although my job was challenging to say the least, resealing pond to perimeter slabs, difficult with water in the pond although I dropped the level. Not tested it yet but if it still loses a bit of water over the too it won't be a fault of this product. Speedy delivery, fair price. Thank you. Judy, Bristol

As described AAA+++

Have used this on various parts of my koi pond setup. Sealing permanent joints in various pipework and filter fittings.As I say it sticks to anything. gloves are a must! This time it was fibreglass to stone joints on waterfall that had opened up and was leaking. Don't try to use on anything you may want to take apart at a later date.I do find that unless you seal an open tube very well and come back to it a month or two later, it will have all set! So the 290ml cartridge is not that economical if you just need a small amount. The one-shot tube is as it says. 'one-shot' So hence the 1-star off as I'd like to see a small say 100-150 cartridge tube that could be less wasteful.I see other comments on the clear version that says it's not so 'good' I have only ever used the black so could not comment on that point.It is expensive but does the job!

I have ordered several of these, over the years, I like to keep one in, as I have a pond with a butyl liner, this stuff is brilliant, says what it does on the tube. It's got me out of a scrape, when rats have chewed my liner a few times. Speedy and safe in the water with fish. Easy to use ,but I would recommend gloves as it sticks really well.

Worked well on the pond but just used it to reseal motorhome windows. The rain was lashing down and the ordinary stuff wouldn't have worked. This did. You might think it's expensive for mastic but for the right job it's well worth it.

Having managed to slice a 2cm hole on a crease in my outdoor pond liner I was unsure how to repair this, a patch was not possible. I did drop the pond level to access the damage so can't comment on underwater use. I inserted the nossel through the liner to hopefully block the hole from behind and also added more on the surface. It might not look pretty but you can't see the repair when the pond is full. The repair seems to be completely watertight so job done. Obviously can't speak for longevity time will tell. It's an excellent product but I found it difficult to get out of the tube, warming it up in hot water helped. Take care it sticks to everything!

Disappointing results - does not stick if surfaces not completely dry. Drained pond for 2nd attempt and stuck patch carefully in accordance with instructions leaving good bead & not pressing flat. Patch stuck very well but minor leak through bead - stuck 2nd patch over top but still very minor leak.

Just as he described, I directly applied this underwater sealant onto the fish tank. The leak problem was solved perfectly