I have a 31000 gallon salt-water (zodiac swg) in-ground pool, vinyl liner. This is our first season and we are just learning all the ins and outs of pool chemistry. My latest readings (from the pool store) are:
t.d.s. - 1000
stabilizer - 40
mineral - 3620
total chlorine - 5
free chlorine - 5
t.a. - 150
adj. t.a. - 135
c.h. - 185
algae - none
clarity - clear
the pool looks good - my concern is that the chlorine value is at 5 -- I've read conflicting things about the recommended level, but I think it should be lower than this. Is it safe for kids to swim at this level? I know that with the salt-water pool, chlorine is still the sanitizer, but I thought the levels were kept quite low (like closer to 1). We did have to do a "super shock" last week in an attempt to deal with phosphate levels of 500 ppb. Phosphates seem to be ranging from 200-500 ppb...not sure why - neighbour fertilizing? scale inhibitor? leaves in the pool? Are phosphates alone, aside from the algae concern, an issue for swimming safety? At what level should they be dealt with? If I leave the cover off for awhile, will the chlorine burn off? Should the swg be turned off to bring chlorine levels down?
Also, is the walmart test kit good enough for the occasional comparison with the pool company readings (we get free water testing there) and to just keep an eye on ph/free chlorine levels?
Also pool company recommends bi-weekly addition of 300 ml of scale inhibitor (bioguard) - is this really necessary? Hate to add chemicals that aren't really needed. They also recommend once a month lite shock + mineral renewal addition...is this a good idea?
Final question - what's the difference between adding lite shock and hitting the superchlorination button on the swg?
Thanks for any help...this site is a great resource!