Closer to Getting Things Under Control... I Think

[rstcso]

My CYA was over 130. After a large exchange of water, it is now reading just over 50. Using TFP's Recommended Free Chlorine Levels set to 60, shows the FC target of 7-9. These are the latest readings using a Taylor K-2006C:

FC - 7.6
pH - 7.5
TA - 100
CH - 160
CYA - 51-ish

PoolMath says to bring down the TA and up the CH. Before coming to this forum. I bought a still-unopened 5lb jug of Zappit 73 Cal Hypo. Would this be an acceptable source to do both? I've read where others have said their CYA level increased after using it. I never want to go through that battle again.

Thank you.

 

[mknauss]

You can use the cal hypo. Be ware the water may cloud when using it.

Keep pH in the 7’s and TA will come down.

 

[rstcso]

I guess I'm assuming since Cal Hypo is an acid it will lower alkalinity. Was this a correct assumption? Or is it even an acid?

 

[mknauss]

It is not an acid. It will likely push the pH up a bit. Will have little effect on TA.

 

[Newdude]

What's the CH of your fill water ? Parts of TX, and to be fair they may be 1500 miles from you , have higher CH fill water. If you do too, undershoot the reccomended level when you add, because it will be rising on its own.

 

[rstcso]

I just exchanged over 10,000 gallons, so I'm assuming the fill water is under 200? But we know what happens when you Rear-u-me (nod to Felix Unger in the courtroom scene on The Odd Couple).

Please correct me if I'm wrong. I believe my first goal should be to lower TA to a target of 70 with MA, then aerate using the grandchildren to get the pH to come up? Once the TA is where it should be, then use the Cal Hypo instead of liquid chlorine to work at bringing up the CH while maintaining proper FC?

 

[Texas Splash]

Normally I wouldn't be too keen on using cal-hypo, but since your CH is only about 150-175 right now you have some room to use it. Once your CH hits about 250-300 I would consider stopping and using just liquid chlorine. While the APP may be telling you to lower your TA, it's not absolutely critical to the point you have to go out of your way. As Marty noted above, each time you lower the pH the TA should lower just a little. The most important issue is the pH. If the pH climbs really fast over 7.8, then sure, take action to lower the TA a bit (about 70) and that should help keep the pH steady. But if your pH doesn't fly upwards too fast, don't rush anything with the TA. Make sense?

As for your FC test above, it looks like you might be using a 25 ml water sample? We generally recommend a 10 ml water sample with ONE generous scoop of powder instead of two. Then each drop counts as 1/2 ppm, so 10 drops to clear would be an FC of 5, 14 drops an FC of 7, etc. It's accurate that way and should save you some powder.