RED SEA - MAGNESIUM PRO TEST KIT REAGENT REFILL Red Sea Sale! from 1599 /per Qty. Add to Cart This item is currently on backorder but you can still purchase it now and we'll ship as soon as more become available. This is the refill reagent for the Red Sea Magnesium Pro Test Kit. The Test kit is sold separately. Magnesium Pro is a high accuracy (+/- 2.5ppm) Titration Test Kit Reagent Refill (75 tests) - incl. professional titrator