Hello, Just finished to assemble my semi in-ground pool. Have zero knowledge about the chemicals. Someone told me not to use chlorine but dichlor in order not to damage the liner. Shell I use the in-line chlorine feeder or just a simple floating chlorine dispenser? I have an oval 12x24 semi in-ground pool with approximately 8000 gallons. What size of the in-line dispenser do I need? Thank you in advance for your answers.