Adding marine sand to a potting mix

[SoulofthePlace]

What do you think marine sand will do to palm seedlings or small plants if marine sand is added to the potting mix while transplanting little palms? We don't have normal yellow construction sand available on the island and therefore everyone uses the grey marine sand (occasionally with some small shells) for construction purposes and after a few years salt crystals are coming out of the walls damaging painted surface etc. Now if I add say 30% of marine sand into the potting mix for better drainage along with perlite, do you think it can potentially damage the potted plants? The marine sand is piled up in the county enterprise and is for sale and it's there for an unknown period of time, so I don't know whether rain has washed the salt away or not. I usually try to use sand that is spread across on the ground and been there for a few years. In the past I have learned the hard way not to feed potted palms an immediate release fertilizer. The result was ALL the potted palms were killed back in the early 2000s..

[PalmsandLiszt]

If you wash it thoroughly with hot/warm water you will easily remove the salt, but it will still be very alkaline owing to all the crushed up shells in it, so it depends what you're proposing to grow in it. A lot of palms want a somewhat acidic medium. You could make up a test pot, water it, let it sit for a few days and test the pH, and compare it with the pH tolerances of whatever plants you want to grow in it.

Or you could just use gravel or grit for drainage.

[SoulofthePlace]

Thanks for your reply. I wonder whether just leaving it for a couple years will rain just wash the salt away from the sand. Or spray it with a hose for a few minutes. I never liked laboratory procedures such as PH testing of the soil etc. neither I know how to do it. I'd rather use perlite or manufactured grit that is crushed stones by a local factory. For potting soil I use 10L bags of potting soil that cost €1,20 per bag as opposed same bags of different brand potting soil cost at least €3. Wonder what the soil consists of and whether it can kill palm seedlings. My palm seedlings do grow in it though.