We have a 125 gallon saltwater tank with a HOB Red Octopus protein skimmer with live sand, live rock and crabs and snails. Wanting to add fish and later some soft coral, but we are having trouble with high nitrate levels. All other water qualities are good. After reading another post, we checked our water source and the water has a high nitrate level. What can we do? Should we add some kind of chemical to the water before putting it in the tank? We are doing weekly 10%-20% water changes, but if the water is high in nitrates from the source, that is not going to help.