Chlorine too low

Hi,
Started my pool up in mid may. My signature has all the salt pool information. Pool is clear which is good but not getting good FC readings. My Test Kit readings are the following:
FC = 0.5ppm
CC = 1.5ppm
CH = 325ppm
Alkalinity = 170
CYA = 90-100
pH = 7.5
Pool temperature is around 85F.

I've put liquid shock in the pool and afterwards then I get a good reading but then the chlorine dissipates in about 1 hour back to 0.5ppm or so it seems. I was previously using test strips, but switched to the recommended test kit TF-1000 I think it's called.

I also had previously put in phosphate remover which at the pool store told me my reading was around 2000ppm, I tested myself and found it now to be around 300ppm.

Any help would be appreciated.
 
With a CC that high and your FC dropping so quickly, there's something living/growing in your pool.

You're cya is also very high and you may want to do a partial drain and refill to get it down to 70ish.

At any rate... You'll want to slam your pool until you get the cc to 0.5 or less and you are able to hold your FC.

Don't worry about phosphates.
 
Slam is to raise the fc level to shock level and not let it drop below until a) you don't lose your free chlorine so fast b) your cc is 0.5 or less and c) your pool is crystal clear.

It requires adding the appropriate amount of bleach and retesting and adding more several times per day.

Your shock level for a cya of 100 is 39ppm. So to bring it to that level to start you'll need 1047 ounces of 8.25% bleach (8.2 gallons). And then you will need to retest every few hours and add enough to bring yourself up above 39ppm.

If you lower your cya by a partial drain and refill, you will need lower FC levels and less bleach.

Make sure to read the articles in pool school on slamming and cya/chlorine relationship.
 
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