Persistent Algae Spots

[Haxzit]

Ok guys I give up and need suggestions. I have scoured the form looking for answers finding the same situation. But not sure if I’ve arrived at the best conclusion. Let me start off will introducing myself. Trust me when I tell you, I am very anal on my pool maintenance and testing. I have become quite the pool expert thanks to this site. I refer all my friends and coworkers to troublefreepool.com. I follow all the forms recommendation's religiously. Weekly testing with accuracy using only Taylor products. Pool is always perfectly balanced every week and always clear. Most of the time only small weekly adjustments need to be made to balance it. Never let levels drop. I do have a SWG and pool runs 8 hours a day. De filtration system that is larger than what is needed for a 8500 gal pool but it’s what came with the house. Also on a side note there is no phosphate in the pool. My problem is I still get algae spots on the Pebble Tec surface. I can manually remove it with aggressive scrubbing but it’s very time consuming. The quickest way to get rid of it, is to Slam it. That will eradicate it and will keep it at bay for about two weeks. Then it comes right back. I don’t understand how this can survive in such an environment. My question is, is there an algicide I can add to my weekly maintenance to prevent it from coming back or am I just stuck Slamming it every two weeks. I’m not against Slamming the pool but I have to time it out because the pool is un-useable during this time until FC levels return to lower levels.

 

[kimkats]

Hi and welcome to posting on TFP! I am glad the site has been able to help you so far. Good job on having the good test kit.

If you have been reading then you know what I am going to ask of you. Please share your last 3 test results like this:

FC
CC
PH
TA
CH
CYA

Is the algae always in the same spot/area of the pool?

We will help you figure out this puzzle. We may ask questions to help us help you.

Kim

 

[Jimrahbe]

H,

You really should only need to SLAM once.. especially in Florida where you never close your pools.

If you are having to SLAM again, then you did not do it correctly the first time.

If you don't have the ability to measure FC up to 30 ppm, then you can't perform a SLAM. Period!!

If you think your CYA is say 50, then you should use the SLAM FC for 60, etc..

Then, when you 'think' that your SLAM is done, then keep it up for two more days, just to make sure.

Thanks,

Jim R.

 

[HermanTX]

My question is, is there an algicide I can add to my weekly maintenance to prevent it from coming back or am I just stuck Slamming it every two weeks. I’m not against Slamming the pool but I have to time it out because the pool is un-useable during this time until FC levels return to lower levels.

Please do not use algicide. That can only add copper or other unwanted items.
You can swim in the pool up to SLAM level FC. However, ensure the pool is clear such that you can see bottom - this is a safety issue.

As others have said, once you SLAM and you maintain your FC in the target range (not the minimum) for your CYA, then algae should not return. Something was not done correctly to remove all algae. Do you have a ladder or maybe water toys that have not been cleaned properly which may still have algae and is being reintroduced?

According to your pool logs you have a CYA of 90 but FC was under 5. That is not acceptable to prevent algae.
Also your CYA is jumping around over the pass month, it is low then high then low again. And your FC is sometimes below minimum for a given CYA. Are you testing CYA properly?

 

[Haxzit]

Hi and welcome to posting on TFP! I am glad the site has been able to help you so far. Good job on having the good test kit.

If you have been reading then you know what I am going to ask of you. Please share your last 3 test results like this:

FC
CC
PH
TA
CH
CYA

Is the algae always in the same spot/area of the pool?

We will help you figure out this puzzle. We may ask questions to help us help you.

Kim

I have linked my pool math so you have access to my past logs. Generally yes it is in same areas. But if left untreated like Slamming or manually removing then it tends to grow.

 

[Haxzit]

H,

You really should only need to SLAM once.. especially in Florida where you never close your pools.

If you are having to SLAM again, then you did not do it correctly the first time.

If you don't have the ability to measure FC up to 30 ppm, then you can't perform a SLAM. Period!!

If you think your CYA is say 50, then you should use the SLAM FC for 60, etc..

Then, when you 'think' that your SLAM is done, then keep it up for two more days, just to make sure.

Thanks,

Jim R.

Ok think you might be on to something. I will try to extend the Slam. Possibly not killing it completely. Just visually the spots look like they are all gone but possibly due to the aggregate surface some could still be thriving after the Slam.

 

[Haxzit]

Please do not use algicide. That can only add copper or other unwanted items.
You can swim in the pool up to SLAM level FC. However, ensure the pool is clear such that you can see bottom - this is a safety issue.

As others have said, once you SLAM and you maintain your FC in the target range (not the minimum) for your CYA, then algae should not return. Something was not done correctly to remove all algae. Do you have a ladder or maybe water toys that have not been cleaned properly which may still have algae and is being reintroduced?

According to your pool logs you have a CYA of 90 but FC was under 5. That is not acceptable to prevent algae.
Also your CYA is jumping around over the pass month, it is low then high then low again. And your FC is sometimes below minimum for a given CYA. Are you testing CYA properly?

Looking the past logs the cya jump this month to 90ppm was me adjusting up from 60 trying to arrive at 75-80ppm. Following pool math instruction guess I overshot it. The cya usually falls around 70-80ppm. I dislike that test and have two by Taylor. I usually do it multiple times and take the closest average. Again trying to be as accurate and exact as possible. And by the way I forgot to add to the original post I do maintain borates in the pool at 50ppm

 

[Bperry]

Looking the past logs the cya jump this month to 90ppm was me adjusting up from 60 trying to arrive at 75-80ppm. Following pool math instruction guess I overshot it. The cya usually falls around 70-80ppm. I dislike that test and have two by Taylor. I usually do it multiple times and take the closest average. Again trying to be as accurate and exact as possible. And by the way I forgot to add to the original post I do maintain borates in the pool at 50ppm

When you last performed a SLAM, did you keep going until you have <= 1.0ppm chlorine loss overnight, had no measurable CC (<=0.5ppm), and water had no visible algae alive or dead? All three of those have to be true at the same time to stop SLAM’ing.

Like mentioned above, you need to keep your FC up in range to stop getting algae. Testing once a week doesn’t sound like it’s cutting it for your situation. This is almost guaranteed why the algae keeps coming back. Algaecide won’t help with that.

Also, be careful with the borates as those test strips go bad very fast.

 

[kimkats]

Have you seen this chart? This might be helpful for the SLAM.

Once the slam is done use this chart for daily care:

 

[Haxzit]

When you last performed a SLAM, did you keep going until you have <= 1.0ppm chlorine loss overnight, had no measurable CC (<=0.5ppm), and water had no visible algae alive or dead? All three of those have to be true at the same time to stop SLAM’ing.

Like mentioned above, you need to keep your FC up in range to stop getting algae. Testing once a week doesn’t sound like it’s cutting it for your situation. This is almost guaranteed why the algae keeps coming back. Algaecide won’t help with that.

Also, be careful with the borates as those test strips go bad very fast.

That must be where I when wrong in Slamming. I took it to 35ppm but didn’t monitor the loss overnight. Just assumed after a couple days at that level with no visible algae. It was gone. I will do it again starting tomorrow. I realize it will be a fight with having high cya. Thanks. Just got new borate strips. Just try and keep it 30-50 range. Thought having borates was a good thing. It you have reservations about the use of it, I would like to hear them.

 

[Haxzit]

Have you seen this chart? This might be helpful for the SLAM.

Once the slam is done use this chart for daily care:

Yes I’ve seen them. Thanks for reposting them for reference. It’s tough to keep the chlorine range with a swg without some swings due to changes in weather. But almost never drops below 4ppm before I’m putting it on a 100% boost or adding bleach to quickly get it back up. Thanks again for taking the time to help me out

 

[mknauss]

Thought having borates was a good thing

They do not hurt anything. Just cost. They do help those with high TA and CH water such that they reduce the pH rise in the SWCG thus keeping it from scaling up.

 

[Bperry]

That must be where I when wrong in Slamming. I took it to 35ppm but didn’t monitor the loss overnight. Just assumed after a couple days at that level with no visible algae. It was gone. I will do it again starting tomorrow. I realize it will be a fight with having high cya. Thanks. Just got new borate strips. Just try and keep it 30-50 range. Thought having borates was a good thing. It you have reservations about the use of it, I would like to hear them.

Like said above, nothing particularly wrong except they are hard to test for and my strips went bad about a couple weeks after opening the container. They started reading higher and higher even though I hadn’t added any more boric acid. So I gave up on the use of it.

 

[PoolStored]

Just got new borate strips. Just try and keep it 30-50 range. Thought having borates was a good thing. It you have reservations about the use of it, I would like to hear them.

First, start here:

Borates in pool - Further Reading

www.troublefreepool.com

Second, there is a drop test that is very accurate for testing. It is "roll your own," but it is accurate and I find it valuable.

New borate drop test at piscines-apollo vs. test strip

Thanks, SunnyBlues. You have been reading and learning a LONG time to remember all those experts. Thanks for your testimonial.

www.troublefreepool.com

Third, be very careful with your pH when you add borates. Use the "effects of adding" to understand the impact. I added borates when pH was 7.6. It lowered and "locked" my pH in at 7.4. This created a situation *with my pool* where my CSI was very negative and created a corrosive environment (****NOTE: Negative CSI does not indicate corrosive...there are other ways to measure how corrosive water is...). Understand *YOUR* pool water environment and target an *end state* pH that is manageable and will not cause problems, as the borates do a VERY good job of buffering pH.

 

[Haxzit]

Like said above, nothing particularly wrong except they are hard to test for and my strips went bad about a couple weeks after opening the container. They started reading higher and higher even though I hadn’t added any more boric acid. So I gave up on the use of it.

I use the LaMotte strips. They seem to be easier to read than the Taylor strips. But again I just try and keep it on the lower end.

 

[Haxzit]

First, start here:

Borates in pool - Further Reading

www.troublefreepool.com

Second, there is a drop test that is very accurate for testing. It is "roll your own," but it is accurate and I find it valuable.

New borate drop test at piscines-apollo vs. test strip

Thanks, SunnyBlues. You have been reading and learning a LONG time to remember all those experts. Thanks for your testimonial.

www.troublefreepool.com

Third, be very careful with your pH when you add borates. Use the "effects of adding" to understand the impact. I added borates when pH was 7.6. It lowered and "locked" my pH in at 7.4. This created a situation *with my pool* where my CSI was very negative and created a corrosive environment (****NOTE: Negative CSI does not indicate corrosive...there are other ways to measure how corrosive water is...). Understand *YOUR* pool water environment and target an *end state* pH that is manageable and will not cause problems, as the borates do a VERY good job of buffering pH.

Thanks for the info. I did read all that before I decided to add borates. Very good stuff. I have also read about the drop test but haven’t tried it yet. But I do what to use that method of testing over strips. As far a rise in ph when adding borates, I used pure boric acid power from dura diesel, giving credit of course to this form, found it better than using borax and chasing ph with acid.

 

[PoolStored]

As far a rise in ph when adding borates

It will lower pH.

 

[Haxzit]

It will lower pH.

Doh! You are correct. Got it backwards. Sorry for the confusion. But I believe you knew what I meant.

 

[Haxzit]

Started Slam today wish me luck. I will post follow up results.

 

[Haxzit]

Update on slam. Tomorrow will be a week and still not passing the ONLT. I’ve cleaned scrubbed and search everything for algae. Yes even behind the light niche and skimmer. Scrubbed the entire pool surface. Cleaned pool equipment, filter and housing. Gone through 10 gallons of bleach. Tested 4 times a day and kept levels up. Still losing on average about 3ppm overnight. Can’t figure out why and seems almost impossible to fall into the parameters to end the Slam. Pool score 1 me 0 guess pool wins this time. Sadly I’ll have to end this tomorrow due to going back to work and will not be able to tend to the pool slam. So have one day left and one more shot at getting it tomorrow morning. It’s very disappointing and feels like a lot of wasted time and effort. But I know this will work, from what I’ve read, and believe in the science. Guess I’ll just wait and see how long before the algae spots come back and try again in the future. Thanks again for all the members support and advice.