And, let me add, test your phosphate AND nitrate. You want phosphate low enough you won't have an algae bloom arriving that drowns your coral---and coral likes nitrate under 20 and lower than that if you can manage it. For soft coral you need those tests plus alkalinity test, which should be around 8.3. For stony coral you need all those 3, plus calcium (s/b 420) and magnesium (s/b) ca 1300, 1350. Corals are easy if you have the lighting (T5 or MH or reef LED) and test your water. Theyr'e living filters, so you can't overstock them.