Reading your post it sounds like you added chlorine and left it in the fresh tank.the chlorine is to sanitize but you need to flush it out of the tank by running water through all faucets and refill with fresh water.
Is it possible you already had a 3/4 full grey tank and now your sensor is reading correct?. You need to empty all tanks and start from scratch.
My 15 Windsor has the fresh tank inside under the bed.easy to inspect.black and grey are underneath.near waste output bay.
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