my pool is inside my house also so I feel your pain. take a plastic bottle with a small opening like a mustard bottle , & fill it with water & food coloring. swim around the edges with snorkel gear & squeeze the dye out while looking for the dye to go into the cracks. if there is a leak the dye will be seen going into the crack. with the pump off squeeze some dye into the drain & all your jets & returns & look for water flow. If this doesn't work a good pool guy will have a camera he can snake through your pipes & find the leak. good luck & post a pic.