Question- TC but no FC

[mbar]

With a cya of 75, you will need to take your ph up to at least 20 ppms for shock - you need to maintain a minimum of 5ppms at all times. Check the "Best Guess Chart" Sticky. I wouldn't worry about going over 20ppms because of all the cya you have in the water.

First I would add some muriatic acid to take the ph down to 7.2. Then add enough bleach to take your chlorine to 20. When your chlorine is at 20 your ph will not test right - it will test high, so disregard the ph till you get back to regular bleach levels. You will know you have killed whatever is in your water when your free chlorine holds overnight. You should test 3x a day and take it back to 20 each time. Keep the filter running 24/7, and brush the walls of the pool. If you do this and be consistant then you should be holding your chlorine level overnight faster. Once your free chlorine is holding, you can let your chlorine drift back down. Then test ph, and don't let it get over 7.8. You can also take your ph down to 7.2 and turn your return jets up to aerate the water, this will take your alk down and raise your ph back up to 7.4 - 7.6. You can do this because your alk is a little high, it should be between 80 - 125 in a vinyl liner. You don't need calcium in a vl, unless you have a heater - your calcium level is good. Feel free to ask any other questions

[mccato]

Thanks, Marie! You're a wealth of information! I'll get started brushing now!