Dichlor / Trichlor & CYA (and an oddity)

Planning to open on Saturday and pulled a water sample for testing (two actually yesterday & today). The pool has been closed since September and my results were identical for both samples are as follows:

FC 12
CC 0.5
TC 12.5
TA 140
CH 350
CYA 75

Question 1 - FC at 12 seems odd. I've always had 0 - 2 when opening. I started using bleach to shock last year and did so when closing. should it still be this high?

Question 2 - this one goes to Dichlor / Trichlor use. We've had a pool frog since buying the pool and it always agitates me that I have to spend $85 - $90 each season for the mineral pack. After reading the info on pool solutions.com I've decided to ditch the frog and go to a straight chlorine feeder. The concern I have is driving up my CYA with the dichlor and trichlor tabs. Should I be concerned? Should I ditch the chemical feeder altogether and just use bleach? if going to bleach, how frequently would I need to add?

Thanks

Doug...

Hi, Doug.
If it were my pool, yes, I would ditch the chlorine feeder and just use bleach. You really don't want a CYA reading higher than 75. Can't really predict how often you would need to add bleach although the good part of having a higher CYA like you do is that it allows you to go a little longer between additions of bleach.

Take a look at the Best Guess Chlorine Chart in my signature below. It gives you the minimum and maximum chlorine levels you need based on your CYA reading. Test every day for awhile and you will soon discover how often you need to add bleach to keep from ever going below your minimum. On the days you do add bleach, add enough to get to your maximum. After awhile, you will learn how your pool behaves and how many days you can go between doses to keep your chlorine level in range.

I think your volume may be a little more like 25,600 gallons. In a pool this size, each 121 oz. bottle of 8.25% bleach will add approximately 3ppm of chlorine. Use that as a reference when deciding on doses. (By the way, what kind of test kit do you have? I'm hoping it is a Taylor K2006 since your CYA is high. I'm assuming it must be since you were able to measure a chlorine reading of 12ppm.)

As far as opening to a chlorine reading of 12, well, I think you are just lucky!

Welcome to the Pool Forum. Let us know if you have any more questions. :)

Edit -- upon rereading your post, I noticed that you didn't list a pH reading. Do you know what it is?

Thanks for the quick response.
Yes, Taylor k2006. Received it Tuesday and put it straight to use.
pH is 7.4
I have 54" pool wall and I keep my water depth at 50". My calc gave me 26,670 with that depth. Sound right?

Last question for now, pool solutions.com recommends polyquat 60 as an algecide but I can't really find much on frequency of use. Should I add at start-up?

You don't have to use polyquat. I never do. It's ok if you do but not necessary. Just keep your chlorine levels in range, and you will be fine. That is the key to avoiding chlorine. It doesn't take long with chlorine dipping too low for an algae bloom to start.

Ok on the volume. I figured water level of 48" instead. And, pH of 7.4 is great.

Thanks for the help. Sounds like it will be a cheap startup this year (hurray!).

You're welcome!