What are some liner developers and sellers saying about professional pond installations that use concrete and rebar, plus mortar to hold the rocks?
(1) “A problem with concrete and mortar construction is the leaching of alkali from the cement for some time after construction, poisoning the pond water with high alkalinity. It also leaves unsightly white deposit buildups in spots outlet and on the surface of rocks in the waterfall”. IS NOT TRUE!
If the concrete you use to pour the shell is a 7-bag mix of 40% gravel and a Stealth fiber mix, the concrete is so dense that even leaching cannot occur. Also, because of the density of the concrete, it is not only waterproof, but stronger than the normal 5-bag mix used for driveways, patios, and sidewalks. Finally, if you coat the finished surface with Thoro-seal, one of several non-toxic concrete sealers, it cannot leach.
(2) “When you use a mortar mix to secure rocks in a waterfall, water penetrating the porous mortar joints filters out the alkali and phosphorescence that poisons the pond. TRUE in the past, but no longer. The mortar regular is porous, allowing water to pass through, dissolving and collecting cement residue.This had been a major concern of mine for many years.After completing a waterfall, I had to let it run for two to three weeks, closing it every 4 or 5 days, and acid clean the white alkaline residue from the rocks that had accumulated.
Then when we were done we would have to acid clean and rinse the pond. Fifteen years ago I discovered a secret formula that would make the mortar mix non-porous and waterproof. It also makes regular mortar mix three times stronger. It is produced by adding one 45# bag of thinset (used to apply ceramic tile to a shower wall) to two bags of Type S mortar mix. Once cured, it becomes so dense that it is completely waterproof and will not leach any alkali after curing (3 to 4 days). Also, this mixture is so strong in its holding power that once it cures, a sledgehammer is needed to remove a rock. In most cases, the rock is broken before being released from the secret formula mortar.
Not only is it waterproof, but it adheres very well to all types and textures of rocks. It will create a watertight barrier that will be useful when building rock dams on the waterfall. The main feature of my special formula is that it allows for much more creativity. It has the ability to raise the water level above the confines of the concrete deck without water seeping through the mortar joints, as is the case with a normal type mortar mix. This special blend is not for sale in stores, and never will be, because the formula is given away for free! This discovery has revolutionized the effectiveness of the mortar mix and its ability to bond, waterproof and prevent alkali leaching.
a dramatic test
A 4,000 gallon pool was converted to a concrete koi pond with two large waterfalls, joined with my new mortar mix, and an 8′ x 12′ island. The rocks surrounding the island were also retained by the new formula. When the project was complete, all surfaces were quickly washed with mild acid, the pond was filled, and a dechlorinator was added. The next day my own $3,000 worth of personal koi fish were transferred to the concrete koi pond. They all leisurely swam around the island, inspecting every nook and cranny.
None of them experienced any stress and they stayed in their temporary quarters for three months without incident. If that dramatic demonstration wasn’t enough to convert the skeptics, nothing will. So what is the conclusion? Pond liners cannot be guaranteed to be leak-free, for a myriad of reasons. Concrete and rebar ponds, if built correctly, will remain leak-free for decades, if not generations. You be the judge. You are the one investing your hard earned money and time into it.