having an issue keeping chlorine levels up. Balance looks good. PH:7:4 Stabilizer:30 Alkalinity:120. I use 2lb granular shock per week, usually Saturday night and by Monday, free chlorine has dipped to 1. I keep 3-4 tabs in the chlorinator for the week. What the heck am I doing wrong. Worried about algae buildup at this rate. Any help would be appreciated.
Chlorine level not holding
- Thread starter Ccross
- Start date
- May 3, 2014
- 58,805
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Welcome to the forum!
What test kit are you using? I would suggest doing an Overnight Chlorine Loss Test if you have a proper test kit.
I suggest you read through Pool School - Trouble Free Pool and even look at a few of our videos TFP-TV - Trouble Free Pool
What test kit are you using? I would suggest doing an Overnight Chlorine Loss Test if you have a proper test kit.
I suggest you read through Pool School - Trouble Free Pool and even look at a few of our videos TFP-TV - Trouble Free Pool
Just using the blue box reagent kit, nothing special. Thanks for the suggestion.
Double check your CYA
With tabs and granular shock, it is probably much higher than 30.
With tabs and granular shock, it is probably much higher than 30.
Please post all your chemistry leveso we can see what you have going on.
- May 20, 2020
- 1,001
- Pool Size
- 13600
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Solaxx (Saltron) Reliant / Purechlor R5
Is the granular shock cal-hypo, or dichlor?
If cal-hypo, what concentration?
Also - how big is your pool?
Sorry, didn’t t see the other questions. 68% concentration. 20,000 gallons. I usually do 2lbs/week
- May 20, 2020
- 1,001
- Pool Size
- 13600
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Solaxx (Saltron) Reliant / Purechlor R5
My guess is that you have algae in the water, just not a concentration that you can see. As Marty recommended above you should do an Overnight Chlorine Loss Test to confirm.
Your method of chlorination isn’t conducive to an algae free pool.
The 2lbs of cal hypo will raise FC about 7.7ppm in a 20,000 gallon pool. That is about 2 days worth in many areas.
4 trichlor pucks are adding 11ppm FC, but at an inconsistent rate, and also adding 7.7ppm CYA each week. That means your CYA level will continue to rise, requiring ever increasing levels of chlorine (which you won’t be adding).
The peaks and valleys of your chlorination mean it’s likely that your FC drops below the minimum on the FC/CYA Levels at least at some point weekly, which invites algae. Once algae is in the water, you need to complete a SLAM Process to eliminate it or you’ll never get ahead.
1. Overnight Chlorine Loss Test
2. SLAM Process if you fail the OCLT.
3. Test and add non-stabilized chlorine (liquid is preferred; the Cal Hypo will eventually cause a calcium build-up in the water) each day to ensure you stay well above the minimum on the FC/CYA Levels.
For any of this to work and be sustainable, you’re going to need a proper test kit. I recommend any of the TF100/TF Pro models from TFTestKits, but you can also use a Taylor K2006-C. See Test Kits Compared for further reading.
Best of luck and fire away with questions.
Your method of chlorination isn’t conducive to an algae free pool.
The 2lbs of cal hypo will raise FC about 7.7ppm in a 20,000 gallon pool. That is about 2 days worth in many areas.
4 trichlor pucks are adding 11ppm FC, but at an inconsistent rate, and also adding 7.7ppm CYA each week. That means your CYA level will continue to rise, requiring ever increasing levels of chlorine (which you won’t be adding).
The peaks and valleys of your chlorination mean it’s likely that your FC drops below the minimum on the FC/CYA Levels at least at some point weekly, which invites algae. Once algae is in the water, you need to complete a SLAM Process to eliminate it or you’ll never get ahead.
1. Overnight Chlorine Loss Test
2. SLAM Process if you fail the OCLT.
3. Test and add non-stabilized chlorine (liquid is preferred; the Cal Hypo will eventually cause a calcium build-up in the water) each day to ensure you stay well above the minimum on the FC/CYA Levels.
For any of this to work and be sustainable, you’re going to need a proper test kit. I recommend any of the TF100/TF Pro models from TFTestKits, but you can also use a Taylor K2006-C. See Test Kits Compared for further reading.
Best of luck and fire away with questions.
Thanks magitek. Very good info. I’m ordering the kit today and will keep you posted. Thanks to all for the help. I’m sure there are going to be more questions after testing.
Kit should be here Monday. I was hoping earlier but coming on horseback ig. I’ll post results once I get them.
Question: if I do end up having to slam, I’ll have questions I’m sure. But do you recommend lc or bleach? And any concern about bleaching out my liner when adding that much?
Question: if I do end up having to slam, I’ll have questions I’m sure. But do you recommend lc or bleach? And any concern about bleaching out my liner when adding that much?
MITBeta
Gold Supporter
- May 28, 2020
- 1,238
- Pool Size
- 13000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
Liquid chlorine is bleach. It's just a question of what the concentration is. Liquid chlorine or pool shock tends to be a higher concentration than household cleaner. Look for 10% or 12%.
You will not bleach your liner if you don't go over SLAM level for long.
Got it. While I’m waiting on my kit to run my loss test and prepare a slam, I’ll probably just supplement my chlorine levels with lc. I guess it’s fine to leave the chlorinator on and let the pucks work along with adding lc to keep the levels up.
Wobblerlorri
Bronze Supporter
- Apr 16, 2019
- 2,010
- Pool Size
- 4024
- Surface
- Vinyl
- Chlorine
- Liquid Chlorine
The trouble with leaving the pucks in is they will raise your CYA levels, leaving you always playing catch up with your chlorine. A better thing to do is remove the pucks and depend entirely on liquid chlorine, 5 ppm daily, which you can figure out with PoolMath. Once your test kit arrives, test your CYA and adjust your SLAM level of chlorine according to the FC/CYA Levels .
Understood. Thank you. So is it recommended to eliminate pucks altogether and just use lc.
Wobblerlorri
Bronze Supporter
- Apr 16, 2019
- 2,010
- Pool Size
- 4024
- Surface
- Vinyl
- Chlorine
- Liquid Chlorine
Finally got my test kit. Here are the results so far.
FC: 2.5
CC: .5
TA: 140
CYA: 40
PH: 7.5
Chlorinator is off and I will check FC again in the morning before the sun comes up.
FC: 2.5
CC: .5
TA: 140
CYA: 40
PH: 7.5
Chlorinator is off and I will check FC again in the morning before the sun comes up.
Wobblerlorri
Bronze Supporter
- Apr 16, 2019
- 2,010
- Pool Size
- 4024
- Surface
- Vinyl
- Chlorine
- Liquid Chlorine
Okay. Your FC should be kept between 5 to 7, with a CYA of 40. See the FC/CYA Levels. Your minimum should never drop below 3. So you're already operating at a disadvantage.
To get the best idea of the Overnight Chlorine Loss Test, test your water in the evening, after the sun is off it, then add enough chlorine to bring it up to between 5-7. Let the pump circulate it, then after 30 min test again. Take that FC as your baseline.
Test again in the morning before the sun gets on the pool. The difference, if any, is your OCLT result. Remember to test both times for CC as well.
To get the best idea of the Overnight Chlorine Loss Test, test your water in the evening, after the sun is off it, then add enough chlorine to bring it up to between 5-7. Let the pump circulate it, then after 30 min test again. Take that FC as your baseline.
Test again in the morning before the sun gets on the pool. The difference, if any, is your OCLT result. Remember to test both times for CC as well.
Thanks for the info. I didn’t bring the FC up beyond the 2.5 before I took my baseline. However, I just retested and is it weird that both FC and CC didn’t drop at all?
FC: 2.5
CC: .5
FC: 2.5
CC: .5