I have a intex 16 x 48 pool. It holds 5061 gallons of water. I have been trying for several days to get a chlorine reading with no luck. I have used the granules , and have used 3 tablets and still have a 0 reading . I put 8 oz of stablizer and conditioner to the pool last night in the skimmer basket, now the bottom of my pool is green. Should I shock it? and if so how much shock should I use?