Summer jumpstart help please

[calgal198]

Hi All,
I did a full battery of tests on my pool water after testing FC/CC, pH and tA for the last few months. Here are the results other than FC/CC
PH 7.7
TA 60 (need to raise it)
Calcium 170 (down from 270 late fall)
CYA ?? Less than 25 (I filled the water to the top of the tester and I could still kinda see the dot)

My questions:
1. Why do I lose calcium? I started with almost no calcium back in October and was warned to be careful adding calcium because once you add it, it stays unless you drain the pool. so I raised it up to 270. Well I haven't drained the pool. We have had some rain and have probably added a couple inches from the tap. Where did it go? Is it normal to lose calcium?

2. How can I guess how much CYA I need? Should I assume I have 20 and add to raise it to 40? I'm in the Woodlands, TX if it helps.

Thanks for the help as always!

 

[pooldv]

Hold off raising your TA. How does your PH act? Does it rise? Drop? Is it stable? If your PH is stable then leave your TA where it is.

What is the CH of your fill water?

How are you chlorinating right now? Bleach/liquid chlorine? If so, and your pool is in full sun or mostly full sun you probably want your CYA at 50. I would add 20 ppm and test it in a week and add more if needed. The lower limit of the test is 30, so with some clouding it is probably between 20 and 30.

 

[calgal198]

Thanks pooldv!

The pH is pretty stable, I only have to add acid maybe once a month?

CH of fill water is 50.

I am chlorinating with bleach and the pool is mostly in the sun. I will raise CYA as you suggest.

Thanks once again!

 

[pooldv]

You're welcome. Definitely leave your TA where it is, only adding acid once a month is nice! With CH that low in your fill water I would raise it to 250 or so, even 300. Rain and dilution will continue to lower it.

Just to clarify. CH will only dilute if it rains enough to overflow the pool and your CH in the pool is higher, i.e. 250, than your fill water, i.e. 50. Otherwise, your CH will climb as water evaporates leaving behind the CH in the pool and the fill water brings in more CH.