I just filled my 1800 gallon vinyl pool with city water. FC is 0 (of course). Pool calculator says to add 24 oz of dichlor to get CYA to 50, but that adding this much dichlor will raise FC to over 50! Is this correct/safe? (Small pool, but I want CYA on high side because so many kids come over and splash a lot of water out that we have to replace. So I thought I'd start with high CYA.) How much dichlor should I add to get CYA up to a smart target from 0? And I think I remember from last summer that I don't add it all at once?