Can never get FC level maintained

[Ohm_Boy]

Chlorine is chlorine. Liquid chlorine from a pool supply is Sodium Hypochlorite. Regular laundry bleach is Sodium Hypochlorite. They will only differ in strength, which may generally be 5.25-6% for bleach, and 6-12% for the 'liquid shock'. Prices are usually comparable per strength and volume, so it'll come down to how many jugs to lug. The pool calculator ( http://poolcalculator.com/ ) is your friend.

 

[Racestud]

Here are latest levels after sweeping pool on waste and adding 3-4 inches of water. And leaving cover off all day.



Fc .2
TC.4
Ta 152
PH 7.4
CYA 41
Ca 415
Salt 3300
Phosphate 750

How much walmart bleach do I need to add to bring to shock levels?

 

[linen]

How much walmart bleach do I need to add to bring to shock levels?

In poolcalculator.com, enter you pool volume, enter your current CYA level the now column of the "CYA" row, then in the "Suggested Goal Levels" row pick "Troublefreepool.com" for the "from" section and select "Bleach" for "Primary Source Chlorine". Now look at the "Suggested FC Goals" row and that will show you your "Shock" level that you want to stay above. Next, go up to the "FC" row and put your current FC measurement in the "now" column and the Shock level suggested in the "Target" row. In the same row select the % Sodium Hyporchorite (Look at the Chlorine source and see what percent of Sodium Hypochlorite it says contains in the fine print). The FC row will now tell you how much to add. You should test as often as possible and keep you FC level above the Shock level. This will take many gallons of bleach/Chlorine, put in the pool periodically.

Assuming you have 6% bleach, CYA of 41, volume of 26500 gallons...poolcalculator suggests a shock FC of 15 ppm. Putting that into the FC row as Target and 0.2 for the now column gives me 813 ounces of 6% bleach, which is about 6.5 gallons. This is just the initial dose , since you want to maintain at least 15 ppm until:

1. CC is 0.5 or lower;
2. An overnight FC loss test shows a loss of 1.0 ppm or less;
3. And the water is clear.

 

[Racestud]

Do have to wait until dark to dump the chlorine in or just until the evening when the sun is behind the house?

 

[frogabog]

You do not have to wait at all. You can begin shocking at any time. It'll take a day minimum and the sun will hit the pool during the shocking process anyway. If you wait to start till night time, you'll just extend your bedtime because you'll still need to test regularly at first and re-dose as needed. At bedtime, you'll want to bump chlorine up a bit to be able to make it through the night and without some data from the previous hours it'll be a shot in the dark how much extra you'll need.

The only benefit to shocking at night is that the sun isn't eating chlorine in addition to the algae. The downside is that you can't replenish chlorine regularly if you expect to get any sleep. As such, the concept of shocking at night to save chlorine only really works if you pull an all nighter.