Please help! Water was clear but yellow strip bottom side of pool under the skimmer and return flow. The only other issue was what looked like lines of brown dirt from center in a couple of places. This brown stuff scattered like dust when brushed. Thought it was mustard algae. FC was 4, CC zero, ph 7.8, CYA 40, alk 90. Added 'yellow clear' and one gal of 6% bleach. Next day, yellow gone, water still crystal clear but now FC is 2 and CC is 10. We have NEVER had CC higher than FC. From the info I've read, if CC is high, then there's still something in my pool, is that right? Do I need to add bleach to shock level (according to pool calculator, I'd need to add 392 oz of bleach). But water 'looks' great. What am I missing?
yellow area under skimmer and return flow
- Thread starter luvsthepool
- Start date
If you have CC over .5 or don't hold chlorine overnight you need to shock until you meet those two criteria in addition to clear water. Check out the pool shocking section of pool school.
Thank you, I thought so but was concerned that CC is way higher than FC. Will shocking increase CC as well as FC?
No, it should not make the CC go up, but down throughout the shocking process.
You get CC when there is something in the pool causing the chlorine to break down. The goal of shocking is to remove/kill whatever is eating up your chlorine so you no longer have CC or the chlorine odor they cause.
You get CC when there is something in the pool causing the chlorine to break down. The goal of shocking is to remove/kill whatever is eating up your chlorine so you no longer have CC or the chlorine odor they cause.
Thank you so much for the help, and the explanation, makes sense. I didn't want to believe something was still there, the water is so clear but the numbers don't lie, do they 
Adding bleach now.
Adding bleach now.
I think sodium bromide which is a huge consumer of chlorine and will account for the cc's.
If something from the pool store says "yellow...(anything)" DO NOT BUY IT