Chlorine levels not increasing

SuperMiguel

Well-known member
Nov 26, 2017
84
Florida
Good morning i have a week old pool, that wont hold chlorine, here are my readings from yesterday:

FC -> 0
pH -> 8.0
TA -> 50
CH -> 250
CYA -> 0

Added about 1/2 gallon of acid, reading from today shows around 7.0 I also added a gallon of liquid chlorine yesterday (Sodium Hypo 10.5%) and still FC sitting at 0 this morning, i also have 2 chlorine tablets inside my skimmer as instructed by PB.

Is there anything else i need to do?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
50,874
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
The half life of FC in a pool without CYA in it is 50 minutes with sun shining on the pool surface.

You need to add CYA.

Remove the tablets from the skimmer. Use a floater whenever using tablets.
 

VinnyinNJ

Well-known member
Jul 20, 2022
291
New Jersey
Pool Size
13500
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Hayward Turbo Cell (T-CELL-5)
When did you add the chlorine? As mknauss said sunlight eats up chlorine. You need to raise the CYA and the best test to see if it's algae or sunlight is to put a jug of bleach in the pool at dusk/night when there's no sunlight hitting the pool, measure after 20 minutes and then next morning measure again before the sun hits the pool. If the FC is 0 then you have an algae eating up the chlorine. BTW, you need a good test kit for accurately analyzing your water.
 

VinnyinNJ

Well-known member
Jul 20, 2022
291
New Jersey
Pool Size
13500
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Hayward Turbo Cell (T-CELL-5)
I used to add CYA right into the skimmer basket and let the filter do it's thing. I have seen that the preferred method is the sock method which basically almost the same thing - fill a sock with stabilizer, put/hang the sock in the skimmer and let it dissolve, this is better for your pumps impeller IMO!

I would add bleach/liquid pool chlorine about an arms length in front of the return. I don't think there will be any reaction with the chemicals.
 

IceShadow

Gold Supporter
TFP Guide
Jun 8, 2019
4,197
Milwaukee, WI
Pool Size
20000
Surface
Vinyl
Chlorine
Liquid Chlorine
There are a couple of issues with adding CYA directly to the skimmer.

1) CYA can get a little soft/mushy as it starts getting wet, and this can cause a clog in your pipes. We've seen it before - search the forums. Not fun to deal with.
2) If it does get through your pipes it has to sit in your filter for a while to dissolve. Most instructions say not to backwash/clean filters for a week (!) while letting the CYA dissolved.

If you put it in a sock and hang it in front of the return jet, it'll dissolve without these dangers. A little squeezing can help it move along. :)
 

SuperMiguel

Well-known member
Nov 26, 2017
84
Florida
Just wanted to double check if you all agree with the NPT startup procedure and numbers, based on this link: National Plasters Council Procedure | NPT Pool Finishes | NPTpool.com here are the numbers they want

pH -> 7.2 - 7.6
TA -> 80
CH -> 200 max
FC -> 1.5 - 3
CYA -> 30 - 50

Here are my results from this morning:

pH -> 7.8
TA -> 40
CH -> 275
FC -> 0.5
CYA -> 30

So i guess i need a bit of Acid to lower my pH, a bit of baking soda to increase TA, liquid chlorine to increase my FC, maybe a tiny bit of CYA to increase my CYA to 40..... Now what do i do about my CH, mine is currently at 275 (Pool math recommends 350) but NPT website says to keep it at 200? So i need to lower it or increase it?
 

Enjoying this content?

Support TFP with a donation.

Give Support

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
50,874
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
The focus of the first 30 days of new plaster should be to keep the CSI between 0 and 0.5, and the FC at 3 ppm with a CYA of 30.
 
Thread Status
Hello , This is an inactive thread. Any new postings here are unlikely to be seen or responded to by other members. You will get much more visibility by Starting A New Thread