Took a quick 4 day family vacation and the weather was in the high 80s/90s with some heavy rains. The water was sparkling and now cloudy with green on edges, walls, and a concentration in the deep 8' part of the pool. I jacked the SWG to 100% and started the robot which hasn't been used in a week. The PH is a tad high at 7.5-7.8 and FC is a touch low but ALK/CYA/etc. are acceptable. The robots are making the floors look better but I still have some green/cloudy. Do I allow the SWG to increase CL and allow the filter to suck the algae out? I am not sure when I need to address with some chemicals.
4 Day Vacation = Algae
- Thread starter sagosto
- Start date
- May 3, 2014
- 58,649
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
7.8 PH
2.5 PPM FC
120 ALK
30 CYA
4 days ago, PH was 7.5, FC was 3.5PPM, and CYA was in the 50 range. Everything was solid for weeks and then I leave for 4 days and we get several high 80s and low 90Fs in a row. Should I assume this is related to the hot weather and not enough chlorine production in the SWG? The FC isn't low so why am I getting algae?
I ran the robot 2 cycles which removed nearly all of the algae on the floor/walls. It was surprising to see that it took 2 full cycles to get 80-90% of the algae and I can see where missed spots. I will use the brush to clean the rest. I turned up SWG to 100%, added a bit of Cyanuric Acid to bring up the CYA, and added 2 lbs of shock (1lbs per 16K gallons). I didn't address the slightly elevated PH given I already added some chemicals and figured I can deal with that tomorrow or the next day. I am going to run the filter all night/tomorrow. It's been 5 hours and it appears to be getting better.
2.5 PPM FC
120 ALK
30 CYA
4 days ago, PH was 7.5, FC was 3.5PPM, and CYA was in the 50 range. Everything was solid for weeks and then I leave for 4 days and we get several high 80s and low 90Fs in a row. Should I assume this is related to the hot weather and not enough chlorine production in the SWG? The FC isn't low so why am I getting algae?
I ran the robot 2 cycles which removed nearly all of the algae on the floor/walls. It was surprising to see that it took 2 full cycles to get 80-90% of the algae and I can see where missed spots. I will use the brush to clean the rest. I turned up SWG to 100%, added a bit of Cyanuric Acid to bring up the CYA, and added 2 lbs of shock (1lbs per 16K gallons). I didn't address the slightly elevated PH given I already added some chemicals and figured I can deal with that tomorrow or the next day. I am going to run the filter all night/tomorrow. It's been 5 hours and it appears to be getting better.
Robots and filters will not remove all the algae. You need chlorine to eradicate it by following the SLAM process. You do that with liquid chlorine, not bags of powder.
With a CYA that low, it is not surprising that the SWG could not keep up.
With a CYA that low, it is not surprising that the SWG could not keep up.
Per TF-100 test kit, the 50 read before I left is acceptable as is the current 30 reading. What am I missing?
Should I get rid of the powdered shock (e.g. Calcium Hypochlorite)? Per a quick search, this has more available chlorine than straight bleach (Chlorine, by any other name, is NOT the same)
Leslie's Power Powder Plus 73% Calcium Hypochlorite Pool Shock 1lb Bags 12-Pack | Leslie's Pool Supplies
Leslie's Power Powder Plus is our strongest pool shock with 73% Calcium Hypochlorite killing bacteria, algae, and contaminants for clear, sanitized pool water.
www.lesliespool.com
TFP recommends a CYA of 70-80ppm for SWG pools. See FC/CYA Levels as well some of the other articles in Pool School.
Now you are in NJ, so a little lower might be fine as it is not as hot and sunny there. But clearly if your SWG running at 100% could not keep up. Then either:
1. You need to run the pump longer
2. You lost all the FC to the sun because the CYA was too low
3. Something is growing in the water consuming the FC faster than the SWG can produce it
4. A combination of the above
Now you are in NJ, so a little lower might be fine as it is not as hot and sunny there. But clearly if your SWG running at 100% could not keep up. Then either:
1. You need to run the pump longer
2. You lost all the FC to the sun because the CYA was too low
3. Something is growing in the water consuming the FC faster than the SWG can produce it
4. A combination of the above
Thank you for the help. To be clear, the SWG was at 80%. It is now at 100% to try and kill the algae along with the shock. After this issue is resolved, I'll dial it back to 80%.
FC was at 3.5 before I left and 2.5 now so there is acceptable chlorine. I re-checked my TF-100 for Alk and having an issue with the test and determining 'red' color. How do you differentiate between a purple/pink vs. red per the instructions? TF's YouTube video says add drops till color doesn't change. Which is correct?
I might have Alk at over 200 which along with the 7.8PH might explain why the FC isn't doing much for me.
FC was at 3.5 before I left and 2.5 now so there is acceptable chlorine. I re-checked my TF-100 for Alk and having an issue with the test and determining 'red' color. How do you differentiate between a purple/pink vs. red per the instructions? TF's YouTube video says add drops till color doesn't change. Which is correct?
I might have Alk at over 200 which along with the 7.8PH might explain why the FC isn't doing much for me.
The pH and TA have nothing to do with your "FC not doing much"
Forget the bags of shock. Follow the SLAM Process.
For all tests, you count drops until the last drop causes to further color change and then don't count that last drop.
Forget the bags of shock. Follow the SLAM Process.
For all tests, you count drops until the last drop causes to further color change and then don't count that last drop.
Interesting as I’ve read high alkaline impacts chlorine availability.
New test
8.0 ph (up from 7.8 pre shock)
6.0 fc
120 alkaline
Used brush to scruff the remaining Algae. It was dark but looks clearer.
Think I’m headed in right direction
I guess the hot weather and only 80% on the swg was the culprit?
New test
8.0 ph (up from 7.8 pre shock)
6.0 fc
120 alkaline
Used brush to scruff the remaining Algae. It was dark but looks clearer.
Think I’m headed in right direction
I guess the hot weather and only 80% on the swg was the culprit?
You might be barely keeping the algae growth at bay now, but you need to eradicate it.
You're wasting time using powder anything when you've got a SWG. IF you need to bump up your FC, liquid chlorine is the fastest best way and doesn't contain any other ingredient which could complicate your chemistry.
Do you know your SLAM process level yet?? Have you read the articles offered up?
SLAM Process
FC/CYA Levels
SWG inject small boluses of chlorine when they're working ("on") but we've found that the CYA needs to be a bit higher to protect all those small amounts from the sun.
When I do my TA test my color goes:
-I first see it go a dull red entirely.... I add and count another drop...
-it then changes to bright pink..... I add and count another drop...
- It then screams at me in BARBIE HOT PINK!.... I add another drop
-Nothing changes so I know I don't count that last drop.
Does that help you at all?
Maddie
Do you know your SLAM process level yet?? Have you read the articles offered up?
SLAM Process
FC/CYA Levels
SWG inject small boluses of chlorine when they're working ("on") but we've found that the CYA needs to be a bit higher to protect all those small amounts from the sun.
When I do my TA test my color goes:
-I first see it go a dull red entirely.... I add and count another drop...
-it then changes to bright pink..... I add and count another drop...
- It then screams at me in BARBIE HOT PINK!.... I add another drop
-Nothing changes so I know I don't count that last drop.
Does that help you at all?
Maddie
you were barely keeping your fc above the minimum for your cya level before your vacation
Such a learning process 
Next steps will be to head to Walmart for bleach and perform cya test to determine shock
After resolved, fc will be sky high. How do I bring that down to normal mid 2.5 levels so pool can be used ?
Next steps will be to head to Walmart for bleach and perform cya test to determine shock
After resolved, fc will be sky high. How do I bring that down to normal mid 2.5 levels so pool can be used ?
FIrst off, a SLAM process is not a one time addition, nor will adding chlorine once kill all the algae. You have to keep the FC level at the SLAM value continuously until the algae is dead, the water is entirely clear. Here is the process:
SLAM Process
The pool can be enjoyed with increased FC *up to SLAM level*.
You idea that "normal" FC is 2.5 is faulty and probably what invited algae to take over in the first place. Chlorine needs to be commensurate with the CYA level. Check this out --> FC/CYA Levels
Maddie
SLAM Process
The pool can be enjoyed with increased FC *up to SLAM level*.
You idea that "normal" FC is 2.5 is faulty and probably what invited algae to take over in the first place. Chlorine needs to be commensurate with the CYA level. Check this out --> FC/CYA Levels
Maddie
You're wasting time using powder anything when you've got a SWG. IF you need to bump up your FC, liquid chlorine is the fastest best way and doesn't contain any other ingredient which could complicate your chemistry.
Do you know your SLAM process level yet?? Have you read the articles offered up?
SLAM Process
FC/CYA Levels
SWG inject small boluses of chlorine when they're working ("on") but we've found that the CYA needs to be a bit higher to protect all those small amounts from the sun.
When I do my TA test my color goes:
-I first see it go a dull red entirely.... I add and count another drop...
-it then changes to bright pink..... I add and count another drop...
- It then screams at me in BARBIE HOT PINK!.... I add another drop
-Nothing changes so I know I don't count that last drop.
Does that help you at all?
Maddie
Yes -- I wish the instructions said to add drops until the color does not change like their video.
If the powder injects a ton of active chlorine, why is the powder/liquid shock (e.g. non bleach) not a valid option? And, why do you specifically mention SWG and powder shock? I am going to shut off SWG during SLAM to ensure I can completely control FC levels. I got jugs of 6% bleach at Walmart so I am armed but just trying to fill in the missing pieces.
FIrst off, a SLAM process is not a one time addition, nor will adding chlorine once kill all the algae. You have to keep the FC level at the SLAM value continuously until the algae is dead, the water is entirely clear. Here is the process:
SLAM Process
The pool can be enjoyed with increased FC *up to SLAM level*.
You idea that "normal" FC is 2.5 is faulty and probably what invited algae to take over in the first place. Chlorine needs to be commensurate with the CYA level. Check this out --> FC/CYA Levels
Maddie
I am slowly learning. This is very helpful
2.5 is in the acceptable range from reading and the pool was sparkling so it was assumed that everything was fine. A few questions:1) If daily FC/PH via TF-100 test kit is performed, why is the FC test even performed if CYA isn't also tested at the same time? Or is the assumption that CYA is already known (from weekly test) and a bit outdated but that's acceptable?
2) My pool is 32K gallons per pool inspection but even if accurate, water level changes so how can you even get the SLAM FC level accurate? Is there a range?
3) Is there a calculator to know how much bleach to add to maintain SLAM FC level?
4) After SLAM is completed via overnight test, I will still have high FC. You said it is OK as long as it is inline with CYA but that still means we are swimming with high chlorine which isn't something I am comfortable with. Since FC/CYA are aligned, how can the FC ever go back down to normal levels?
4) The Chlorine/CYA chart for SWG (Chlorine / CYA Chart - Trouble Free Pool) only has metrics for 70-80 as 60 has * for 'not recommended'. That's a very narrow window of CYA to maintain. Is that correct?
- Mar 24, 2014
- 2,455
- Pool Size
- 32000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool SJ-55
1 Unless you have a significant water exchange, CYA doesn't change much. Can go longer between checking
2. Start with 32k. If you notice that pool math doesn't work exactly right, you can adjust your estimate accordingly.
3. PoolMath
4. The CYA buffers the chlorine. A FC of 5 with a CYA of 50 is less available chlorine than FC=1 and CYA of 0. "Normal" is anywhere between minimum and SLAM. Chlorine will go down, but it needs to be replaced before you fall below minimum.
4 It's not a rigid number, but a guideline. 70 would be a good place to start. Some people run 60, some people run 90. The test is only valid +-10ish anyway.
2. Start with 32k. If you notice that pool math doesn't work exactly right, you can adjust your estimate accordingly.
3. PoolMath
4. The CYA buffers the chlorine. A FC of 5 with a CYA of 50 is less available chlorine than FC=1 and CYA of 0. "Normal" is anywhere between minimum and SLAM. Chlorine will go down, but it needs to be replaced before you fall below minimum.
4
It's not a rigid number, but a guideline. 70 would be a good place to start. Some people run 60, some people run 90. The test is only valid +-10ish anyway.1 Unless you have a significant water exchange, CYA doesn't change much. Can go longer between checking
2. Start with 32k. If you notice that pool math doesn't work exactly right, you can adjust your estimate accordingly.
3. PoolMath
4. The CYA buffers the chlorine. A FC of 5 with a CYA of 50 is less available chlorine than FC=1 and CYA of 0. "Normal" is anywhere between minimum and SLAM. Chlorine will go down, but it needs to be replaced before you fall below minimum.
4
Excellent. I thought FC was AC.
If we assume 70 CYA and current FC of 5, the target SLAM FC is 28. PoolMath says to go from 5 to 28 is 1530 oz of 6% bleach or *13* 121 ounce jugs? 13??? That cannot be correct?
- Mar 24, 2014
- 2,455
- Pool Size
- 32000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool SJ-55
That sounds about right to me. That is why the article says
If it is not practical to replace the water, the 28 number is what it is.
e: I just reread the thread. Your current CYA is 30? Then you are good to go! SLAM the pool, when the process is complete, increase CYA to 70ish and go from there.
If it is not practical to replace the water, the 28 number is what it is.
e: I just reread the thread. Your current CYA is 30? Then you are good to go! SLAM the pool, when the process is complete, increase CYA to 70ish and go from there.
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