We purchased a home at the end of the season which came with a freshly built ~26k gallon in ground pool. The equipment includes a Pentair 320 auto chlorinator which I’ve been adding chlorine pucks too. The water is crystal clear right now (paid a company to open the pool a few weeks ago). Using the TF-100 testing kit the chlorine level keeps falling. The test block level is showing 0.5 (free or total chlorine?) and the ph has consistently been 7.3. I’m new to owning and managing a pool. I’ve converted the Pentair auto chlorinator to top feed from bottom feed which seems to have helped a little bit. However the pool is not consuming the chlorine pucks fast enough. How can I get the chlorine level higher? Is shock my only option? Is there anything to look for when selecting a shock to use?
How do I get chlorine higher?
- Thread starter nopeeinool
- Start date
- May 3, 2014
- 58,834
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Welcome to the forum!
Post up a full set of test results.
Use liquid chlorine to maintain FC in your pool water. Pucks are not sustainable.
I suggest you read through Pool Care Basics - Trouble Free Pool and even look at a few of our videos TFP-TV - Trouble Free Pool
Post up a full set of test results.
Use liquid chlorine to maintain FC in your pool water. Pucks are not sustainable.
I suggest you read through Pool Care Basics - Trouble Free Pool and even look at a few of our videos TFP-TV - Trouble Free Pool
Thanks mknauss,
I’ll read up. Are there certain results you’re looking for? I can take a water sample to my local store for complete results if my test kit does not suffice.
Your test kit is far more accurate than a pool store test could ever hope to be.
Run through a full suite of tests (use the FAS-DPD powder-and-drop chlorine test, not the comparator block, just to rule out color issues), and provide them like so:
pH:
FC:
CC:
CYA:
CH:
TA:
As stated by Marty, pucks do not work for long term use. Liquid chlorine ("shock") or a SWCG is the way to go.
Run through a full suite of tests (use the FAS-DPD powder-and-drop chlorine test, not the comparator block, just to rule out color issues), and provide them like so:
pH:
FC:
CC:
CYA:
CH:
TA:
As stated by Marty, pucks do not work for long term use. Liquid chlorine ("shock") or a SWCG is the way to go.
Nice choice of username. 
And Welcome.
Do you know the pool temp ? Pucks are slow in cool water and it may be that simple if the UV from the sun increased more than it warmed up.
And Welcome.
Do you know the pool temp ? Pucks are slow in cool water and it may be that simple if the UV from the sun increased more than it warmed up.
Thank you for all your help. The pool temp is 68-70F. Here are the results (first number is my test results testing with TF100 test kit, 2nd number is the results from taking a sample to the pool store)
ph: 7.2 (from comparator block), 7.4
FC: 1 ppm, 0.4 ppm (target 1-4)
CC: .5 ppm, NaN
TC: 1.5 ppm, 0.7 ppm
CYA: 45 ppm, 57 ppm
CH: 875 ppm, 468ppm
TA: 15, 95 (target -125-150)
Phosphate NaN, 247
What I notice, in addition to the low Chlorine, Calcium Hardness is high - this something to worry about? Are any of the numbers something to worry about?
I purchased liquid Swin Shock at 12.5% (strangely the bottle says 15%) - using the TFP Pool Math calculate stated I added 22oz. Hopefully this works
ph: 7.2 (from comparator block), 7.4
FC: 1 ppm, 0.4 ppm (target 1-4)
CC: .5 ppm, NaN
TC: 1.5 ppm, 0.7 ppm
CYA: 45 ppm, 57 ppm
CH: 875 ppm, 468ppm
TA: 15, 95 (target -125-150)
Phosphate NaN, 247
What I notice, in addition to the low Chlorine, Calcium Hardness is high - this something to worry about? Are any of the numbers something to worry about?
I purchased liquid Swin Shock at 12.5% (strangely the bottle says 15%) - using the TFP Pool Math calculate stated I added 22oz. Hopefully this works
- Mar 5, 2020
- 3,141
- Pool Size
- 66000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V35
This pool store nonsense needs to go. They tell everyone to maintain some chlorine. And HEY !!!! It works for tap water so why not ?
Welp. The sun is why not. The sun will burn up to 4 ppm a day in the peak season by you. The hot climates may see even more. Nowhere do they tell people that they could be adding FC every hour or two all season to achieve the 1 to 4 recommendation during daylight.
Swimming is also why not as that will waste some FC also.
CYA is also also why not as it binds about 90% of the active sanitizer in chlorine so as the CYA goes up, the FC needs to rise proportionately to match it. All levels on this chart are equal for sanitizing.
We round the CYA up so we will call yours 50. Notice your dose (high) target so it falls to low target, while having some wiggle room above min.
Every day. Adjust daily target for recent daily loss for that part of the season.
******* back to the current issue
Run an overnight test for FC. Test in the dark both times, being well mixed. If you lose FC with no UV, then it's algae
Overnight Chlorine Loss Test
Last edited:
MITBeta
Gold Supporter
- May 28, 2020
- 1,238
- Pool Size
- 13000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
That will barely raise FC by 1ppm in a 26kgal pool. You need more like 8ppm more to get started and see if FC will hold.