So my RO/DI's carbon cartridge expired early, and this happened at the same time I set-up a 40g African Cichlid breeder tank. I had used what I thought was pure RO water to soak and rinse my sand (caribsea zack sand), filter media (matrix, siporax, sponge filters), and rocks (coral base rock, lava rock, slates, pagoda) to remove any dust and whatnot. I also set up the tank by pouring this RO water & sand into the tank, then conditioning it to the correct levels, including using Prime. Ever since, I've had an issue with chlorine leaching into my tank. Even after large water changes and double dosing Prime to remove chloramines, it still creeps back. I've already done a complete teardown, replaced the RO cartridge, soaked the sand in water that was rotated with heavy dechlorinator, rinsed with RO, and used new media for the filters... and now the problem has come back, even after large water changes, and dosing with Prime. The only thing I didn't soak in dechlor was the rocks, which were left to dry for a week. I'm going to tear it down again, but I'm wondering if anyone has had this issue before, and how they resolved the leaching. Am I better off not re-using anything within the current set-up? Is there a length of time I should be dechlorinating the sand/rocks (48 hours last time), and is it possible by not soaking the rocks that chlorine is leaching and bonding with free ammonia in my tank? Either way this problem is driving me insane, and staying true to my username, I'm close to hitting the reset button on everything... just want to know if everything exposed in the tank is unusable at this point, or if it can be saved; given how porous the sand/rocks/matrix/siporax, is there any combination of soaking/dechlor/direct sun to get any of the chlorine that might be leaching from them out? Thanks in advance.