JoeyM SuperDork
4/6/12 1:31 p.m.

OK, this one is WAY off topic, but it always seems as if one of you guys has a reasonable answer to anything I ask, so I'll try again; Please teach me about sealants for concrete aquariums.

We're building a semi-large (e.g. 500 gallons) concrete pond in the bottom of a greenhouse. What should we use to seal the concrete without poisoning the critters we want to put in the tank. Is Koi-Kote the best option, or is there something out there that is more appropriate for the person with a GRM-buget?

4cylndrfury UltimaDork
4/6/12 1:43 p.m.

standard pond liner sheeting wont work?

JoeyM SuperDork
4/6/12 1:52 p.m.

We're actually putting in two of them - one salt water, one freshwater. The salt one is in ground, and the freshwater one is above ground. Our profs have declared that the tanks shall have concrete bottom and sides. There was a reason for this, but I don't recall it.

DaveEstey Dork
4/6/12 2:36 p.m.

I think there's a site like that would have your answer.

motomoron Dork
4/7/12 5:19 p.m.

I would think EPDM pond liner would do it.

Lesley UberDork
4/7/12 5:41 p.m.

Please tell us you're going to post pics!

I second monsterfishkeepers – some incredible setups in there.

JoeyM SuperDork
4/13/12 10:10 p.m.
Lesley wrote: Please tell us you're going to post pics!

As you wish.

Here are some construction pictures.

The salt water pond, not yet sealed

upper level of two-tier freshwater tank. The wall at the left will be notched to allow a waterfall into the lower level

photo showing both levels

students digging out one of the raised beds to make room for another freshwater pond

Lesley UberDork
4/13/12 10:12 p.m.

Wow! What a huge project – but the results are going to be worth it. Impressive!

JoeyM SuperDork
4/13/12 10:34 p.m.


The one the students were working on is actually going to be around the base of an artificial tree that will be covered in arboreal plants that like it VERY moist. The "trunk" will contain a pump that pulls water out of the pond and forces it to the top, where it can trickle back down to the pond. In the process, it will keep the plants growing on the "tree" nice and wet.

Brett_Murphy Dork
4/14/12 8:27 p.m.

I want to put a pond type aquarium in my yard so bad, and I was thinking about doing the two tier one the guy in the blue shirt is standing in up on the top photo.

JoeyM SuperDork
4/14/12 9:20 p.m.

That's me....the tank actually has one additional level halfway between the visible one and the bottom where I am is no wider than a stair step. The reason we are looking for an inexpensive sealant is that the recommended ond costs as much as the concrete.

TRoglodyte Dork
4/14/12 10:27 p.m.

Talk to your local Mason or paint supplier. wall looks well parged, mix a waterproofing agent in final coat and it cure

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