Waterproofing concrete pond: plaster, fiberglass, painted-on rubber?

[moocowman]

I'm building 3 foot wide x 20 foot long x 30 inch deep rectanglar in-ground concrete pond. I've already plumbed and I'm just starting to install rebar. I can't decide on a method of waterproofing the pond. It's being built like a swimming pool. So I was thinking of plastering it like they would a pool. I've watched several videos of people using fiberglass to waterproof (seems like mostly in the UK). I've done a lot of fiberglassing before. I'd probably use epoxy resin instead of polyester resin. I'm torn on any products that are paint brush or roller applied. I see a lot of good reviews, but also a lot of bad ones reporting failures. It seems like the film thickness isn't enough to be durable. I don't want to use a rubber liner because I can't hide the edges of the liner and I seems sealing around fittings like the returns, main drain and skimmer would be difficult since all the parts are made for concrete pools.

Would someone with professional experience or someone who has had a waterproofing method hold up for decades chime in with some advice?

 

[Lisak1]

Welcome @moocowman !

Not a lot of folks with concrete ponds here - most are EPDM lined ponds - but hopefully someone will chime in with a helpful answer.

@GBBUDD - any help here?

 

[j.w]

@moocowman
Me too, no experience w/concrete, sorry.

 

[GBBUDD]

There are companies that can make you any size box shape you want that has welded seams. They will never fail I believe they are pvc base product. Not to be confused with cheap pvc sheeting. It is a flexible material similar to EPDM.
The key to any of the other applied coatings is the concrete it's self . The preparation timing and application method is critical. Some demand the concrete still be green so the coating can blend with the concrete . While others demand the concrete be clean ,dry and solid.
I have seen where a spray on liner like rhino liner truck bed liner spray has been used. I know I bought a cheap brand years ago that came with a gun that let's just say didn't even try to eliminate orange peel texture. But I can assure you it was water tight. Can I say it was fish friendly no . But I doubt it wouldn't be toxic as most of those are a urethane base and those to my knowledge are fish friendly.

And like you mentioned there is plaster nothing wrong with plaster in any way when applied properly can give you 20 years with no issues. But eventually will start to alagator Crack. But this is a proven product as swimming pools are still using plaster to this day.

I will add that generally the higher the psi of concrete the more water resistant that it generally is. For my money plaster and some die would be my choice white however would not be my first choice as it will show the algae and the greens and brown that just look dirty.

 

[Laaf]

My concrete ponds are just concrete. No waterproofing was applied.

 

[GBBUDD]

You can get specific mixes that are waterproof but they can get pricey. 5000 psi is close add fiber and additive and you got some strong stuff.

 

[zeuspaul]

I used Rapid Set mortar mix available at Home Depot and Lowes to seal my concrete block pool. I troweled it on. It is stronger than portland cement products and doesn't shrink. Over ten years and still holding water. I did not want to use epoxies or paint because of the difficulty of getting something to stick years later if it needed repairs.