how to maintain fc with bleach

miahhough · May 29, 2012

I'm currently using an in-line chlorinator (with 3" pucks). My fc won't hold. It drops slowly over a few days. I can't figure out if i have algae or bad chlorine pucks. my water looked really good saturday but my ph was a little low so i added some ph+ to it. it imediately clouded my water and it's SLOWLY getting better. my FC was 2 saturday and cc was .5. i checked it today and fc was 0. i've put bleach in it to get it up to 4.0 which is where the chart shows it should be with cya=50.

is there a formula that shows how much bleach to add each day to maintain fc or do you just have to test it daily and use the calculator? the pucks would be very convenient but i'm about to give up on them. any thoughts?

JasonLion · May 29, 2012

The amount of chlorine you need varies from pool to pool, season to season, and with things like the number of people swimming. There is no one setting that will always work, no chart that says add this quantity and you are good. There are levels you can aim for, but the quantity required to reach that level varies. Beyond that, you also need to get your other levels right and make sure you don't have algae or other obvious problems.

Richard320 · May 29, 2012

Daily testing and dosing is the way to go. After several weeks, you'll learn what "normal" is for your pool, and can sometimes get away with just adding the "normal" amount without testing, and adjusting things properly the next day.

And DO lose the pucks. They add CYA to the water. The chlorine breaks down, the CYA does not. It just builds and builds and builds until there is no "unstabilized" chlorine available to kill algae, and pretty much no amount of chlorine will clear the pool.

If you don't have a proper test kit, get one. Now. You may very well be on the verge of an algae bloom, and you'll a good test kit to tame the pool.

ROB N · May 29, 2012

FWIW, 4 is the very minimum.FC should never get below 4 with a CYA of 50. See this link pool-school/chlorine_cya_chart_shock but if you have been using pucks I have a feeling your CYA may be much more than 50ppm. Daily testing, putting those results into the pool calculator and adding the appropriate chemicals in the correct amounts is the way to go. 10-15 min a day and you can have perfectly clear and sparkling water. But you need a high quality test kit!

miahhough · May 30, 2012

i have the tf100 test kit. i was just trying to get an idea of the what it would cost to maintain it with bleach vs pucks. obviously bleach is the way to go - i was just curios if it would cost more or less. maybe i'll just use the pucks when we know we are going to be gone for a couple days.

any chance the pucks i have are bad?

Butterfly · May 30, 2012

miahhough said:
i have the tf100 test kit. i was just trying to get an idea of the what it would cost to maintain it with bleach vs pucks. obviously bleach is the way to go - i was just curios if it would cost more or less. maybe i'll just use the pucks when we know we are going to be gone for a couple days.

any chance the pucks i have are bad?

The pucks are fine. They are hard to kill when properly stored.
Lots of folks save them to use for vacations.

chem geek · May 30, 2012

In general, Trichlor pucks/tabs are more expensive when you account for the pH/TA adjusting chemicals you need to add. See Cost Comparison of Chlorine Sources. Though the prices are old, the relative prices still roughly apply.