I wish you luck. I think you will need it. In my almost 65 years, I have found that you get what you pay for. Glenda

i used Drylok on my 4000gal cement Koi pond 4 years ago and it has never leaked and is fish safe. try Home depot or Lowes, about $20 a gallon

I am in a state of shock! No one can say why exactly what the Romans did for their cement to last so long and exposure to modern atmosphere has been speeding up deterioration. Some very strange things have been tried in attempts to duplicate that material including adding urine and blood. Modern polymers are pretty cheap and easy compared to bleeding an ox or goat whenever you want to keep a bit of concrete together and I don't want to know what your local department of health will say if you try it.
The parafin application is going to be a disaster that can't be fixed. It will attract every stray bit of dirt and debris in or out of the water which will turn ugly fast and will be a bacterial stew in short order. Artisans who use parafin for waterproofing blend it with alcohol and lots of buffing to make it form a hard surface and mineral oils and heat to make it spreadable. Water will turn it white and soft and anything will scratch it.
Sherri Warner Hunter has two excellent books on ways to manipulate concrete. They are available on Amazon along with books by several other authors. Sandy

Anything is worth a try, as long as you're ready for the consequences. Sounds like you like to experiment, but remember we still don't know how the ancient Romans were able to accomplish much of what they did (the aqueducts still amaze me). I would highly suggest you try this experiment on a smaller scale first. This way if it's a total disaster, you haven't caused any damage to your real liner. That's what a real scientist would do. I know because I'm married to one! Doing it this way will save you considerable headache and expense in the long run if your idea is not a success. (I don't think most ponders would keep this a secret if it worked for them. Usually people love to brag.)

I waterproofed the concrete wall that forms my basement with Thoroseal. It is a masonry product that comes in bags (maybe 70 pounds or so). You just mix it with water and brush it on. I don't think it was too expensive, since I waterproofed about 800 square feet of wall, and would have noticed the cost if it was great. I would think a bag or two would do it. I can't vouch for it as a pond product, but my wall never leaked a drop

Here is a link that might be useful: Thoroseal

I have a question about these sealers - are they transparent? what would you recommend for mortared stone? (Must be fish safe)

I've been trying to figure out the waterfall/basin part of my pond and while it would have a liner underneath the main (largest) portion of the pond, it would really help if I didn't have to mess around with concealing a liner under the waterfall/basin section.

Take a look at this sealer. The manufacturer states it can be used for sealing fish ponds and it is transparent.
"Horton"

Here is a link that might be useful: Concrete and stone sealer

Thoroseal is a cement product, so it is definitely not clear. As for fish safe, I think it would have the same problems as any cement product, i.e. alkalinity.

I've been looking into an epoxy product called Pond Armor for a geyser-type fountain we are building. Everything I've read about it and the feedback I've gotten from some of the reviewers on their site sounds solid. Experimentation on a large scale usually turns into nightmares on a large scale. If you are not 100% sure of the outcome, you might end up paying as much for a commercial product with all your work going into in the first place.

Here is a link that might be useful: Pond Armor

I have just used Pond Armor and found it very difficult to use and spread. The 1.5 quart only covered about 20 square feet even though it claims to cover 60 at 10mills. I would not recommend Pond Armor to anyone. I ended up wasting a sponge, a roller, gloves, scraper as the mixed content is so difficult to apply.

I have read drylok or thoroseal may be the way to go. I am at the point where I either need to purchase a pond liner which I reluctantly want to do or try another sealer, any comments ?

I spent a lot of effort on mortaring And concreting the pond, only to use a liner as pond armor is such a disappointing product. Does anyone know if drylok or thoroseal are similar ?

Thanks

I finally ended up using Thoroseal. I am very happy with the results. All I can say is stay far far awAy from Pond Armor. It is very expensive as this topic suggests and not worth it. Thoroseal is a relatively inexpensive product and works like a charm. If you have mixed Mortar before, Thoroseal is similar and very easy to work with.

My pond has been running for approximately 1 full month with positive results.

You can see it here http://concretepond.blogspot.com

Thanks

Here is a link that might be useful: Concrete pond with Thoroseal

I used Thoroseal a few years ago to seal my pond (link below). It was easy to mix and easy to apply. Since then, some hairline cracks have appeared in the surface of the Thoroseal.

I am thinking of applying a layer of Herculiner in the spring. Herculiner is a DIY polyurethane truck bedliner. The stuff is extremely durable, and should be able to present an unbroken surface to the water despite any fine cracking underneath. It is also easy to apply, so finessing it around the skimmer and rock wall should be no problem.

Here is a link that might be useful: applying Thoroseal to my concrete pond

In respect what the Romans used in making concrete. They used milk and animal fats, Google 'milk in Roman concrete'.

If you are planning on putting fish or plants in the pond, DON"T USE THE HERCULINER! I used it on several truck beds, it's great for that, but it has a LOT of petroleum based solvents in it, the last truck bed I did had little oil rainbows on it for months after it rained. I have used Thoroseal professionally, and it is a great product, I have also had real good luck with Sunny Day Foundation waterproofer, ( on line from Lowes at $29 for gray and $33 for white. This is a 60 pound bucket, coverage is around 440 square feet, I did a mild acid wash after removing all loose material, also use the Sunny Day bonding agent with it. A second coat is required after 1 hour, I have used it to repair/reseal old fountains with great results. I also filled in cracks with a crack filler, such as K-tite water plug. Sunny Day is safe to use on potable water tanks.

From what people have posted, it looks like Drylok, Thoroseal mixed with Acryl-60 or Sunny Day Foundation waterproofer might be the least expensive/easiest option for sealing an outdoor fountain.

Do all of these require the same type of prep? Anyone know which ones are the most "forgiving" for less than perfect prep? Years ago I purchased a 3 part fountain and I think it is made of concrete which seem to have become porous.

7 year old trivia question on how water features worked 2000 years ago...credit doesn't go to cement mixes, they leaked plenty. The secret is they had a continuous water source. Aqueduct, ditches and even pipes diverted water from streams at higher elevation, ran into fountains (no pumps needed) and then out of the fountain into maybe a bath house and then thru a sewer and on away from the city. So it was OK for stuff to leak some.

Curious to hear how the wax thing worked out.

Best sealer I've found is no sealer. Liner covered with concrete or mortar. Has never failed me and is super cheap and easy. Pretty hard to mess up. Allows very reliable pipe penetrations. I also prefer the look of aged concrete so that can be done too.

Sealers require stable concrete. Different sealers can span some tiny cracks but even hairline cracks can cause failure. Which is why swimming pools and professionally built concrete ponds and water features are so thick and use so much steel.

Concrete over liner only needs 1" or so of concrete and no steel (steel is bad in this case). If the outside of the fountain is to be visible you create in a standard way, thick and steel. Then liner and another 1" of concrete. Only you will know there's a liner.

I
agree that they’re too expensive. I have a pond with a raised bed decorated in
sandstone. I did some concrete
waterproofing using a liquid membrane because the liquid type can penetrate through
the small areas. I found this to be an effective way to waterproof the
concrete.

fish safe is different from no leaks. Seriously, cement is way wrong on the pH and leaching chemicals. I used a fish safe epoxy from PondBiz.com. It worked great but it turned yellow and eventually cracked off the water fall rocks. The fish were fine in their big plastic bowl held by concrete.