In short, I am looking for a fluid that meets these criteria:
- Denser than water
- Low viscosity
- Food safe
We are working on adding a pool and designing a backyard recreational area. One design element that we would like to include in multiple places is waterfalls of varying sizes and styles; I love flowing water. As an extension of that I started wondering if it would be possible to create an underwater waterfall.
Initially I was thinking this could be accomplished by creating a regular waterfall in the pool with normal water, which could then be capped with a clear glass or acrylic watertight cover. This certainly works as an underwater waterfall, but the cover will be visible, and will likely cloud over time, not to mention the condensation issues.
So I'm wandering now if some sort of fluid exists that could actually flow underwater. If it's dense enough it will flow down a rockface even under the water, and if hydrophobic will not mix with the surrounding water. As it will be within a pool that humans will be in for extended periods it must be externally safe, and I'd like something food-safe as kids swallow pool water and it's possible this stuff might get kicked up. And to add to that tall order, the wrong viscosity will ruin the visual effect.
Does such a fluid exist in a form that a normal person can purchase for a reasonable cost? I live in the US (Pennsylvania). Another question, Is there a readily available liquid that's more dense than water and insoluble?, seemed to be looking for something similar but the answer doesn't meet my safety requirements.