Clear Blue Water but still new algae everyday

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
11,295
Houston, Texas
If your CYA is at 30, should your Shock level only be 12?
That is what confused me about the , non SWG and SWG, CYA/FC chart. Don’t mean to confuse, but if CYA is 30 you may be wasting Chlorine.
@bjsbuds I think you are somewhat confused. Right now your CYA is 30ppm as per your post, your slam level should be FC 12ppm, not FC 24ppm. Do not use the SWG daily targets for your slam level. Slam level is based on CYA only. Reading the article I could see where you would think you need 24ppm, but you do not. Going forward target 12ppm for your slam level.
 
  • Like
Reactions: bizurk1

jseyfert3

Well-known member
Oct 20, 2017
253
Janesville, WI
At the bottom of the article it says:
The best solution to this is simply shut off the SWG, Liquidator, injection pump, etc. and use liquid chlorine only for the duration of the SLAM
I agree it's a bit confusing how it's laid out. In plain terms, for the duration of the SLAM, turn off your SWCG. Refer to the Chlorine/CYA Chart and look at the non-SWCG Pool portion. Since your CYA is 30, your SLAM level is 12. I agree it's a bit confusing. 60 ppm CYA is not recommended for a SWCG pool, but that doesn't mean you use the FC levels for 60 ppm when you have 30 ppm.

Once your SLAM finishes, you'll add CYA to bump your pool up to 70, restart your SWCG, and target a FC of 5 per the SWCG pools section.

Hope this helps.
 
  • Like
Reactions: bizurk1

bjsbuds

LifeTime Supporter
Mar 16, 2012
127
Cincinnati, OH
Today's readings and action taken:
7am FC = 25
9:30am FC = 22, added 1/2 jug of bleach as suggested by PM
3pm FC = 18, added 1 jug of bleach as suggested by PM
9pm FC = 16, added 1/2 jug of bleach as that is all I have left.
As fast as I am losing FC, must still have algae present. Off to buy more bleach in the morning.

SWG has been turned off all week.
 

bjsbuds

LifeTime Supporter
Mar 16, 2012
127
Cincinnati, OH
At the bottom of the article it says:

I agree it's a bit confusing how it's laid out. In plain terms, for the duration of the SLAM, turn off your SWCG. Refer to the Chlorine/CYA Chart and look at the non-SWCG Pool portion. Since your CYA is 30, your SLAM level is 12. I agree it's a bit confusing. 60 ppm CYA is not recommended for a SWCG pool, but that doesn't mean you use the FC levels for 60 ppm when you have 30 ppm.

Once your SLAM finishes, you'll add CYA to bump your pool up to 70, restart your SWCG, and target a FC of 5 per the SWCG pools section.

Hope this helps.
Wow, you are right, along my journey, I have been told FC needs to be maintained at 30, 24, 20, and now 12. Whatever the right number is, why am I losing FC so quickly? For example, FC was 25 first thing this morning, and after adding two jugs of bleach during the day, I am ending up at 16 FC. Water looks beautiful, have scrubbed walls and floor twice today.
 

cfherrman

TFP Guide
May 10, 2017
2,211
Hays, Kansas
Ok ok, slow it down.

Is your cya 30? If so do not go above 12 FC!

you are losing FC due to the sun because you are going way too much above shock level if 12.
 
  • Like
Reactions: bizurk1

jseyfert3

Well-known member
Oct 20, 2017
253
Janesville, WI
Wow, you are right, along my journey, I have been told FC needs to be maintained at 30, 24, 20, and now 12. Whatever the right number is, why am I losing FC so quickly? For example, FC was 25 first thing this morning, and after adding two jugs of bleach during the day, I am ending up at 16 FC. Water looks beautiful, have scrubbed walls and floor twice today.
Two reasons. First, the more FC, the faster the sun will distroy it. Second, algea requires a lot of FC to distroy once it's established, so your FC demand will be high throughout the SLAM. That's why it's recommended to check and adjust FC so often. The article says twice a day is the bare minimum, and more often up to once per hour is better.

I'm not sure why people are listing different CYAs. I'm mobile right now, I'll browse back through when I get to work and see if there was a reason for that.
 

bjsbuds

LifeTime Supporter
Mar 16, 2012
127
Cincinnati, OH
Checked the pool four times so far today. Trying to hit the 24 FC mark. 7am it was 22 FC, then a few hours later it dropped to 20 FC, added one jug of 10% bleach, a few hours later it was 22 FC, and a few hours later it was 20 FC, so we added one jug of Kroger, lesser strength bleach. Shut off the pump long enough to clean the four cartridge filters. I really thought they might be more dirty, but there was some. Will check it one more time today. Headed back to Lowe's tomorrow to purchase the 10% bleach.

A couple ways we can see if the algae is still present is on the white steps, and then when we run the dolphin APC, and there is algae (brown grit) in the filters. Earlier today definitely present, second time around not nearly so.
 

jseyfert3

Well-known member
Oct 20, 2017
253
Janesville, WI
@bjsbuds,

Went back through the thread from the start of this year. The reason the suggestions for FC level during SLAM keep changing is because you keep reporting a dropping CYA level. The FC level for SLAM depends on the CYA level. At the start of this year's portion of the thread, you said the CYA was 55 (rounded up to the nearest 10, that's 60). Then you said it was 50, then 40, and finally you said it was 30.

From the Chlorine/CYA Chart, the proper FC level for a SLAM is:
CYA Level (ppm)FC Level for SLAM (ppm)
2010
3012
4016
5020
6024
7028

As you can see, since you kept reporting a lower CYA level each time you tested, the suggested FC level from the members lowered along with it. If your CYA really is 30 ppm, then trying to maintain 24 ppm FC means you have twice the recommended FC for a SLAM, and it will burn off in the sun quickly. Hence it's important to have a good solid CYA test to know what the CYA level is so you know what FC level you need to target.
 

bjsbuds

LifeTime Supporter
Mar 16, 2012
127
Cincinnati, OH
@bjsbuds,


As you can see, since you kept reporting a lower CYA level each time you tested, the suggested FC level from the members lowered along with it. If your CYA really is 30 ppm, then trying to maintain 24 ppm FC means you have twice the recommended FC for a SLAM, and it will burn off in the sun quickly. Hence it's important to have a good solid CYA test to know what the CYA level is so you know what FC level you need to target.
Yes, you are correct, I have reported a declining CYA level frequently, which is correct. But, since members have said only test FC, I have stopped testing for CYA. Are you suggesting that I now start testing CYA again and follow the chart for the correct FC level based upon that?

I appreciate everyone's help and support. Sorry, that this seems so challenging for me. Just checked FC level and it is 23, so all good so far.
 

jseyfert3

Well-known member
Oct 20, 2017
253
Janesville, WI
Yes, you are correct, I have reported a declining CYA level frequently, which is correct. But, since members have said only test FC, I have stopped testing for CYA. Are you suggesting that I now start testing CYA again and follow the chart for the correct FC level based upon that?

I appreciate everyone's help and support. Sorry, that this seems so challenging for me. Just checked FC level and it is 23, so all good so far.
No, I'm not saying that. However, it's might be something we need to look into. It's not expected that CYA will change over the course of a SLAM, so it's tested for at the start, then assumed it stays there through the duration of the SLAM. Honestly, I think it kind of got missed that your CYA was declining, since there are multiple people responding. CYA dropping is very odd. With very rare exceptions, CYA breaks down only very slowly in pools. The typical way a pool looses CYA is through water replacement. Ways to loose CYA therefore include rain causing the pool to overflow or require draining, backwashing a filter, or otherwise loosing water (leaks/splashout) and replacing it with tapwater. Are any of these happening to you? You have a cartridge filter, so you wouldn't be backwashing. Are you draining any water, or adding unusually large amounts of water (perhaps indicating a leak)? Note evaporation and replacement of evaporated water will not cause CYA to drop, only splashout, overflow, drainage, or leaks will cause a CYA reduction.
 

bjsbuds

LifeTime Supporter
Mar 16, 2012
127
Cincinnati, OH
Hmmm, not too sure about the CYA. Very weird. I'll try to do a quick overview; sick of opening a pool full of algae, and liner was bleached out, so decided to replace liner and fill with all new water. Unfortunately, before liner was replaced, pool company showed up without scheduling and started opening the pool. They removed two of the plugs, so all that algae water filled the plumbing pipes. I was very frustrated with them, but nothing I could do at that point.

Completely drained pool, liner was replaced, and fresh water added to fill pool. Was always worried about that algae water in the plumbing once we turned on the pump. Once the pump was turned on and new cartridges put in the filter, I never noticed any green water. But, before long there was brown algae on the steps and in the bottom of the pool.

I always get a little lost starting the pool in the Spring, and it is hard for me to understand this whole SLAM process. Not to mention how frustrating it is to literally pour money down the pool. We have put over 50 jugs of bleach in the pool, and yet we can't stabilize the FC. So, on to today. FC was 18 this morning, meaning we lost 6 over night. Put a jug of bleach in the pool, but by noon, the FC was down to 15. Purchased another 12 jugs of 10% bleach at Lowe's today. Added 1 1/2 jugs per PoolMath calculator. FC back to 23, with the target being 24.

Will this ever end?
 
Last edited:

bjsbuds

LifeTime Supporter
Mar 16, 2012
127
Cincinnati, OH
No, I'm not saying that. However, it's might be something we need to look into. It's not expected that CYA will change over the course of a SLAM, so it's tested for at the start, then assumed it stays there through the duration of the SLAM. Honestly, I think it kind of got missed that your CYA was declining, since there are multiple people responding. CYA dropping is very odd. With very rare exceptions, CYA breaks down only very slowly in pools. The typical way a pool looses CYA is through water replacement. Ways to loose CYA therefore include rain causing the pool to overflow or require draining, backwashing a filter, or otherwise loosing water (leaks/splashout) and replacing it with tapwater. Are any of these happening to you? You have a cartridge filter, so you wouldn't be backwashing. Are you draining any water, or adding unusually large amounts of water (perhaps indicating a leak)? Note evaporation and replacement of evaporated water will not cause CYA to drop, only splashout, overflow, drainage, or leaks will cause a CYA reduction.
We have not added any water other than the initial fill of the pool after liner replacement. We have received some rain, which did not caused the pool to overflow. So the pool water is the water from the initial fill, of course losing some to evaporation, and adding some from rain.
 

Frodo

Member
Jul 5, 2014
12
Central New Jersey
We have not added any water other than the initial fill of the pool after liner replacement. We have received some rain, which did not caused the pool to overflow. So the pool water is the water from the initial fill, of course losing some to evaporation, and adding some from rain.
You really need to test your CYA again. If you're at 30, you're just wasting bleach. Take a step back for a moment and stop adding bleach until you test CYA.
 
  • Like
Reactions: bizurk1

jseyfert3

Well-known member
Oct 20, 2017
253
Janesville, WI
Hmmm, not too sure about the CYA. Very weird. I'll try to do a quick overview; sick of opening a pool full of algae, and liner was bleached out, so decided to replace liner and fill with all new water. Unfortunately, before liner was replaced, pool company showed up without scheduling and started opening the pool. They removed two of the plugs, so all that algae water filled the plumbing pipes. I was very frustrated with them, but nothing I could do at that point.

Completely drained pool, liner was replaced, and fresh water added to fill pool. Was always worried about that algae water in the plumbing once we turned on the pump. Once the pump was turned on and new cartridges put in the filter, I never noticed any green water. But, before long there was brown algae on the steps and in the bottom of the pool.

I always get a little lost starting the pool in the Spring, and it is hard for me to understand this whole SLAM process. Not to mention how frustrating it is to literally pour money down the pool. We have put over 50 jugs of bleach in the pool, and yet we can't stabilize the FC. So, on to today. FC was 18 this morning, meaning we lost 6 over night. Put a jug of bleach in the pool, but by noon, the FC was down to 15. Purchased another 12 jugs of 10% bleach at Lowe's today. Added 1 1/2 jugs per PoolMath calculator. FC back to 23, with the target being 24.

Will this ever end?
I understand this is frustrating. I do think we need to get a grasp on this CYA issue though. Were you always testing it with the same lighting? The general recommendation is to stand outdoors with your back to the sun and the tube as waist level. Can you try and get another reading? If you're really at 30, you're burning off a lot of FC during the day from the sun by targeting 24. You only need 24 if your CYA is at 60. You also risk bleaching liners by drastically exceeding the shock FC level for a given CYA level. So it's important to know what the CYA actually is, and it's worrying it seemed to drop over time.

Perhaps someone can chime in on if high FC levels mess up the CYA test for some reason.

Once we get this under control, here's some advice for the future. Do not winterize your pool under the water temp stays under 60 °F. Yes, this will probably be some time after you stop swimming for the year, but until the water drops below that 60 °F mark, you need to keep running the pump and adding chlorine as if you were swimming. Once spring hits, monitor the water temp. As soon as it hits 60 °F, it's time to de-winterize it, fire up the pumps, and start adding chlorine. My understanding is that algae usually does not grow under 60 °F, so by closing late and opening early, you keep the algae from growing at all, which means you don't have to SLAM on startup. In fact, if you don't have to SLAM on startup because you opened the pool when the water hits 60, and monitor and maintain the FC according to your CYA level throughout the year, you should never have to SLAM (or shock) the pool, because it stays perfectly sanitary and algea free if maintained at the right FC level for the CYA.

So, keep up the motivation! We'll get there! And after we do, don't be a stranger. At the very least come back in the fall and we'll help you properly close the pool, so you don't have an algae filled one next spring.

TFP extended test instructions for CYA: CYA - Cyanuric Acid Test - Trouble Free Pool
 
Last edited:

bjsbuds

LifeTime Supporter
Mar 16, 2012
127
Cincinnati, OH
Good morning,
Just tested, FC is 21, with my target being 24. It is cloudy and raining here in OH, third day in a row. Tested CYA, holding waist high on the deck with a much light as I could get. CYA = 40. Is there something more I should be doing? I am headed down to put 1/2 jug more bleach in according to PoolMath before heading off to work.
 

Mr Bruce

TFP Guide
Mar 24, 2014
2,222
Greenville, SC
I think @bjsbuds is shocking for mustard algae. That would explain the 24 ppm.
a) I don't believe they have mustard algae and

b) Even if they did, the instructions for addressing it indicate you SLAM "normally" and then only briefly raise the FC level to the higher number. You are not supposed to maintain it throughout the SLAM.

To permanently get rid of mustard algae, you first SLAM the pool normally, following the directions in How to SLAM Your Pool. Once you have completed SLAMing your pool in the standard way, raise the FC level up to the extra high mustard algae shock level for 24 hours. Use PoolMath, or see the Yel/MstrdShock column in the chart in this post, to find your mustard algae shock level.
 
  • Like
Reactions: zea3

Other Threads of Interest