Red Sea Fish Pharm ARE21426 Reagent Phosphate Pro Refill Kit for Aquarium, 100 Tests Phosphate pro refill kit is an advanced colorimetric test with comparator Measuring the level of phosphate in reef aquarium to an exceptionally high accuracy of 0.02ppm PO4 This test kit, when used in conjunction with the nitrate pro test kit, enables accurate dosing of NO3:PO4-X (biological nitrate and phosphate reducer) This kit includes a durable, chemical resistant plastic case, analytical grade glass vials Includes material for up to 100 tests