http://www.aquarticles.com/articles/...ete_Ponds.html
In this article by Doug Hoover - he answers two questions with interesting answers if true. I like to get your opinions on if he's right:
(1) "One problem with concrete and mortar construction is that of cement alkali leaching out for some time after construction, poisoning the pond water with high alkalinity. It also leaves unsightly white deposit build-ups at the points of exit and on the surface of rocks in the waterfall."
NOT TRUE! If the concrete you use to pour the shell is a 7-sack mix with 40% pea gravel and stealth fiber mix, the concrete is so dense that no leaching can even occur. Also, because of the density of the concrete, it is not only waterproof, but stronger than normal 5-sack mix used to pour 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 mortar mix to secure the rocks in a waterfall, the water that soaks into the porous mortar joints, leaches out alkali and phosphorescence that poisons the pond.
TRUE in the past, but not anymore. Regular mortar is porous, allowing water to pass through, dissolving and collecting the cement residue. This had been a major concern of mine for many years. After the completion of a waterfall, I would have to run the waterfall for two or three weeks, shutting it off every 4 or 5 days, and acid-clean the white alkali residue off the rocks that had built up. Then, when we were finished, we would have to acid clean and rinse out the pond.
Twelve years ago I discovered a secret formula that would render 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 it cures, it becomes so dense, it is totally waterproof and will not leach any alkali after it cures (3 to 4 days). In addition, this mix is so strong in its holding ability that once it cures, a sledge hammer is needed to remove a rock. In most cases, the rock breaks up before coming free from the secret formula mortar.
Thoughts?
For the rest of the article visit the link above.