Biofarmacja, opinions and questions

Good morning, please advise. From the indications of a cardiologist (sport) I take Magne B6, but due to the difficulties in swallowing (and possibly crushing tablets) I am looking for forms of magnesium (citrate, lactate) to drink, but proven manufacturers available in pharmacies, not on forums. I found Magnesol, but I don't like the taste, so I keep looking. I'm interested in two: 1) "BioPharmacy BioMagnez", which has "Magnesium citrate (derived from the water of the Dead Sea)" - my question: What is the significance (apart from marketing) of the fact that it comes from the Dead Sea? 2) ForMeds F-Mag B6 has "magnesium citrate 850 mg, including magnesium 135 mg (36% NRV)" - how to understand this information (with other products with citrate there are no phrases "including magnesium")? What magnesium preparations with good bioavailability (for drinking) can pharmacists recommend? Thank you.