Algae again - no clue where to go from here....

[shawnra]

So this is my first year with a pool - we built it last summer and only had it open about 2 months last summer so this was my first full summer. I found TFP while we were building and I spent quite a bit of time reading up on chemistry management and thought I had a good handle on what to do. I bought a TF100 test kit and have been religious about testing and maintaining the water chemistry.

Opened this spring in early April. It took me about a month to get all the chemicals where I wanted them. About the end of May I saw just a little algae on the bottom and thought I should SLAM it. This was my first time through a SLAM and I am not sure I did it exactly right, but it went away and all looked good. It took about 10 days to complete.

Pool was only clear for a little over 2 weeks and the algae was back again. SLAMed one more time. This time I removed light niches, ladder and return nozzles to make sure everything was clean. Again - about 10 or 11 days to complete SLAM and had it all back clear again for July 4th.

This time it stayed good for almost 6 weeks til mid August. I checked clorine every couple of days and it never dropped below 5, but again the algae came back. The water was still fairly clear but there was just a dusting of green in spots across the bottom. So lets SLAM again. By now I am pretty sure I am following the directions exactly. CYA was 65 and so I raised CL to 26 and held it between 25 and 30 for 2 full weeks. Was all good again by around 27th of August and so swimming once again.

Last week i see a small spot once again!! I am at wits end so I break down and consult the pool builder. These guys also do pool maintenance for a number of large pools so I hope they have some idea that can help. They tested the water and told me the salt was low (it was at 3000 as I had been backwashing and replacing water), but everything else looked ok. They thought it might be high phosphates and said they would come by and test it and have a look at the equip to make sure its all good. Long story short they said everything looked fine but that the CYA was 80 and that could interfere with cl ability to kill algae. When I tested with TF100, I consistently got 55, and he was using same type of reagent, but he got a very different result. When he came by, the algae patch I had seen appeared to be gone, so he said watch and see how it goes. He suggested running the pump longer (I only run it about 14 hours a day when not SLAMing), but said everything looked fine. Of course I look at the pool 36 hours later and I can see algae growing over about 10% of the pool bottom. I am going to let it go for a few days to get worse before I call him back, but this is really crazy!

So in general, I have been targeting:
Fc 4-6
pH 7.5
TA 70
CYA 70-80
Salt 3400

At this moment, I have:
FC 8.0
CC 0
CYA 55 (by my measurement - is there a more accurate test I can find?)
TA 70
pH 7/5
Salt 3450
CH 50

I run the pump 14 hrs/day at 2000 rpm so I should be getting plenty of circulation.

Any thoughts? Its a nice looking pool, but I'm about ready to throw in the towel...

 

[PAGirl]

You should trust your own readings over the pool store. For an SWG, though, your CYA should be 70. Do you brush the pool regularly? You should stop asking the pool store for help, there methods are usually compatible with the TFP ways.

Did you pass the OCLT when you did your last SLAM?

 

[Paul.]

Hi Shawnra,

Simply, Algae will not grow in a pool that has proper FC level according to CYA,
So of course there must be something wrong and we will try to help. Is it possible that your FC drifts lower than 4ppm during the day? I see that you test your FC "Every Couple days". With an algae problem, you should really be testing every day.

I see that you slammed several times this year, My question is, when you slammed did you pass all 3 criteria before letting the FC drift down to normal levels? How many times a day do you test during the SLAM?
1) clear water
2) Pass OCLT
3) CC less than 0.5

Your tests results will be more precise than the pool store. They often are no help.
You will need to get you CYA between 70-80 and keep it there,
and you will need to start another slam,

Can you explain your method for a SLAM, maybe you are doing something wrong? Are you making sure to shut off the SWG and only using bleach while you SLAM? Having SWG while you do the OCLT will give you false results.

Also, how is the circulation in the pool? How many intakes and returns do you have? Sometimes bad circulation can prevent proper sanitation.

 

[Catanzaro]

I can see you Skimmers from the pictures. Where are the main drains? Also, how many returns do you have? If you followed the SLAM procedures properly and your levels have not drifted, while using the recommended test kits, then more than often, it is either poor circulation in some parts of the pool and/or lack of brushing.

If your pool returns are spaced properly from your skimmers, maybe installing these types of returns would make a huge difference. Please remember that your PH will increase based on pump running time. So if not used to rising PH, you will have to adjust your chemical additions of MA. I have a friend who had only 2 returns in his pool and had same issues. This did the trick. The more returns you have, the less of these you will need. I have 4 rotating heads and 2 regular in the pool and 2 in the steps.

The Circulator Rotating Water Jets for Swimming Pools - YouTube

Amazon.com: Circulator 10022a Automatic 360 Rotating Swimming Pool Cleaner Jet with Water Control Bottom Cap: Patio, Lawn Garden

Pump running time must be 24 hours a day until the SLAM process is completed (No exceptions). Other items Paul & PA Girl covered in other responses. You do not need Phosphate Removers and they are not recommended.

Q: How often do you backwash? With a sand filter, you should only backwash when pressure exceeds 25% of normal operating pressure. Too much and frequent backwashing is not recommended as your filter will not be as efficient.

 

[sundaze]

Have you pulled out the lights and checked behind them? I had algae return a couple of weeks after a slam and when I removed my light I was amazed at what I found hiding behind......

Dave

 

[Texas Splash]

Shawnra, everyone's comments/suggestions above are spot-on. Right now, focus on completing every technical aspect of the SLAM, to include passing the 3 criteria. After that, adjust CYA to the recommended levels for a SWG pool (70-80) which will protect your FC better. Definitely trust your OWN tests. You have a great test kit, so use those numbers. Even though you've done the CYA test before, let's make sure you have some good notes to go with along with the TF-100 instructions:

Proper lighting is important for the CYA test. You want to test for CYA outside on a sunny day, but keep the skinny view tube in the shade. Taylor recommends standing in the sun with your back to the sun and the view tube in the shade of your body. Use the mixing bottle to combine/mix the required amounts of pool water and R-0013 reagent, let sit for 30 seconds, then mix again. Then, while holding the skinny tube with the black dot at waist level, begin squirting the mixed solution into the skinny tube. Watch the black dot until it completely disappears. Once it disappears, record the CYA reading. After the first test, you can pour the mixed solution from the skinny view tube back to the mixing bottle, shake, and do the same test a second, third, or fourth time to instill consistency in your technique, become more comfortable with the testing, and validate the CYA reading.

Other than that, hang in there. I have to say ... WOW! Gorgeous pool. Love the set-up. Good luck!

 

[shawnra]

I am going to wait a couple of days to start the next SLAM to take advantage of the free time on the weekend, and post some notes, but after going through it 3 times, I feel comfortable with the process and I have read through the procedures many times...i dont think I am missing anything. Each time through the SLAM, I passed all 3 tests: the water has always remained clear, the cc has never been higher than 1 and always at 0 when I stopped SLAMing and although I stopped the first SLAM when OCLT showed 0.5 drop, I carried the second and third SLAM through to 0 loss. I kept pumps running 24/7 and shut off SWG at night when testing.

Thanks for the suggestions on circulation. I am leaning toward some mechanical cause because the water chemistry seems to behave as expected. I have 2 skimmers, floor drain and 6 returns that are fairly evenly distributed, though not perfect. I have been running the valve on the main drains about half closed just because I want the skimming action - could that be an issue? Do I need to open that up all the way? I am not opposed to getting the circulating returns - actually Id do about anything to see if it would work.

I guess I will pull the lights when I SLAM this time (I did do this the second time, but didnt the last time). Anyone else have globrites? These seem to be stuck into the niches with no real means of keeping them there and when I pull them out, it seems like it have to shove them in a few times before they seat well and stay in. Doesnt seem to be a good design.

As for backwashing, I feel i dont do it often enough. Thats about the only thing that I dont record in the log, but I think I do it about every other week. Ill start keeping that in the log as well so I can be sure, but I dont think I am doing this too often. Catanzaro - can you explain what goes wrong when backwashing is too frequent? Is there something I can watch out for or a sign this may be the issue?

I am interested on the brushing comments. I brush when SLAMing to get rid of the algae, but so I need to do this regularly? I have a maytronics dolphin and I run that once a week or so - does that cover it or should I be brushing the bottom every few days?

And in conclusion...Thanks so much for the suggestions! I really appreciate the feedback.

 

[Texas Splash]

Good notes and questions. Opening your main drain more may not really solve your algae issue. As long as the water is being circulated relatively well, that's most important. I have no experience with Globrite lights. Sorry. Just do the best you can I suppose. Maybe someone else has them and can clarify. Backwashing is generally done when pressure increases 20-25% from your baseline (clean) starting pressure. Of course when you SLAM you may find yourself doing it a bit more to comply with the SLAM page instructions and removing dead algae, but that's expected. It is always a good idea to brush your pool on a regular basis, perhaps a couple times a week. Just like our teeth, your pool surface can develop a thin film if not brushed which can enhance the opportunity for organics to adhere to. But as I highlighted above, I would encourage you to not only trust your own testing, but definitely confirm your CYA as best as you can to ensure you are not only at the correct FC level, but that your FC is properly protected all day from the sun. SGWs are great for convenience, but because they are designed to generate such a relative low FC level, that precious FC needs good protection.

One last thought .... when you pass your SLAM, if you haven't done so already, make note of the surrounding areas of your pool to ensure the stuff in your pool may not actually be pollen or dust. Think of it this way, if you have algae in your pool, your FC level should be dropping faster than normal. The FC gets used-up by the organic material. That's why we do the OCLT. FC gets lost either from the sun or organics. So if you pass an OCLT, you should be relatively confident there is no algae in the water. On that note, when you do an OCLT, just remember that it must be done when the sun has dropped – no sunlight on the pool. About 8 hours total is recommended. If you use a SWG or automatic chlorinator, make sure they are turned-off or set to zero. Also, your FC level should be elevated more than normal. Starting (bedtime) FC could be close to your SLAM level, but no lower than 10. Anything less and you may not receive an accurate portrayal of FC loss (by percentage), even if it’s only 1 ppm.

 

[Catanzaro]

Shawnra:

I am assuming you only saw algae spots here and there. Please look at spots (if so) and determine if the returns are moving water in those areas as this could be a lack of circulation. The main drain helps, but it is not the problem.

That is quite a large pool and 6 returns should do it. The volume of your pool is twice the size of mine, and I have 8 returns. Also, a couple items that I have uncovered as mentioned before. My friend who changed the only 2 returns he has to the circulator ones did the trick. I can not promise you that this is the solution, but it worked for him. Maybe start with 2 of them (free shipping) and work up to at most 4.

The other item that I uncovered is that if you have people in the pool, 5-10 with lotions, soap, fragrances, etc., your daily consumption could be between 4-5 ppm. I ran a few tests, and in the three times, every time from morning to evening, there was a 4.5 ppm loss. It is pretty significant when you have activity with children, lotions, etc. So you kind of have to experiment with your own pool. Maybe levels dropped for a short period of time and came back up to normal levels. Also CC levels increase very quickly for a short period of time when children are present.

Test before the activity, make sure you are the right levels and add enough to compensate so there is no drop during the day that would make you fall below your minimums.

There have been posts where returns have been moved around and dye has been used to make sure that chlorine has circulated properly. I can promise you that the rotating heads are excellent. It is worth the $70 investment for a few of them. Keep us posted.

 

[ping]

Have you performed an OCLT lately and what is the result?

What was the typical OCLT result at the beginning of the other SLAMs?

Are you using the FAS/DPD test for daily test during the year or are you using the OTO test?

 

[ewkearns]

I'm going to guess that we have one or more of the following going on:

1) The SLAM was not completed properly, IOW one of the following was not satisfactory:
a) clear water
b) Pass OCLT
c) CC less than 0.5
d) lack of ACCURATE test results.

2) Over time, free chlorine may have fluctuated to an extent that it allowed algae to re-establish a hold on your pool and/or....

3) .... the chlorine has not "gone" where it needs to "go." That could be poor circulation or trouble spots like stairs (inside tubing, etc.), drains, or behind light fixtures. Exceptional measures such as removal and cleaning with bleach may be in order.

Once algae is truly defeated, it won't come back, if there is sufficient sanitizer in contact with it.....

 

[Tanner M]

I am going to wait a couple of days to start the next SLAM to take advantage of the free time on the weekend, and post some notes, but after going through it 3 times, I feel comfortable with the process and I have read through the procedures many times...i dont think I am missing anything. Each time through the SLAM, I passed all 3 tests: the water has always remained clear, the cc has never been higher than 1 and always at 0 when I stopped SLAMing and although I stopped the first SLAM when OCLT showed 0.5 drop, I carried the second and third SLAM through to 0 loss. I kept pumps running 24/7 and shut off SWG at night when testing.

In the last sentence you state that you turned SWG off at night during testing. Are you saying that you were running the SWG during the day while you were SLAMing the pool?

 

[shawnra]

Great suggestions - let me try to answer the questions:

Texas - I will do an OCLT tonight prior to SLAM. I think my FC is 9-10 since the weather has cooled and I havent adjusted my SWG cycle. I will report back results.

Catanzaro - I have had no real bather load since labor day since it got cool here, so I dont think thats it, but it could be. I think circulation is a better bet and I am going to look into that.

Ping - OCLT typically showed 3-5 ppm drop at the beginning of the SLAMs with FC near 25-30. I only use FAS/DPD test these days.

ewkearns - I get your point and should make sure, but I can guarantee that water was clear, and my OCLT and CC results indicated SLAM worked and was complete. Obviously my results could be inaccurate, but not sure how. I do FAS/DPD so often that I am buying new chemicals so they are fresh and I use a speedstir for testing so mixing should be throrugh and consistent. Are there other things I could be messing up? Open to suggestions, but it seems straight forward.

Tanner - I do run SWG during the day when slamming. I found I was able to keep FC more constant during the day when I am at work and not able to test repeatedly and add more bleach as necessary. I tried to shut it off an hour or two prior to testing at night when doing OCLT so that it had cisrculated and was more likely to be accurate.

I'll also try to get a pic. I suppose it's possible that it is dust or pollen, but it seems unlikely to me. Of course, if I knew the answers, I'd be swimming

Thanks guys!

- - - Updated - - -

one more thought...

If it were a circulation issue, would I be able to test different areas and see varying FC levels?

 

[PAGirl]

Great suggestions - let me try to answer the questions:

Texas - I will do an OCLT tonight prior to SLAM. I think my FC is 9-10 since the weather has cooled and I havent adjusted my SWG cycle. I will report back results.

Catanzaro - I have had no real bather load since labor day since it got cool here, so I dont think thats it, but it could be. I think circulation is a better bet and I am going to look into that.

Ping - OCLT typically showed 3-5 ppm drop at the beginning of the SLAMs with FC near 25-30. I only use FAS/DPD test these days.

ewkearns - I get your point and should make sure, but I can guarantee that water was clear, and my OCLT and CC results indicated SLAM worked and was complete. Obviously my results could be inaccurate, but not sure how. I do FAS/DPD so often that I am buying new chemicals so they are fresh and I use a speedstir for testing so mixing should be throrugh and consistent. Are there other things I could be messing up? Open to suggestions, but it seems straight forward.

Tanner - I do run SWG during the day when slamming. I found I was able to keep FC more constant during the day when I am at work and not able to test repeatedly and add more bleach as necessary. I tried to shut it off an hour or two prior to testing at night when doing OCLT so that it had cisrculated and was more likely to be accurate.

I'll also try to get a pic. I suppose it's possible that it is dust or pollen, but it seems unlikely to me. Of course, if I knew the answers, I'd be swimming

Thanks guys!

- - - Updated - - -

one more thought...

If it were a circulation issue, would I be able to test different areas and see varying FC levels?

I believe so. But you would need to collect it from near the bottom. For the surface, some suggest using ping pong balls.

 

[ewkearns]

ewkearns - I get your point and should make sure, but I can guarantee that water was clear, and my OCLT and CC results indicated SLAM worked and was complete. Obviously my results could be inaccurate, but not sure how. I do FAS/DPD so often that I am buying new chemicals so they are fresh and I use a speedstir for testing so mixing should be throrugh and consistent. Are there other things I could be messing up? Open to suggestions, but it seems straight forward.

Sounds like you are getting things done properly, but I see I didn't make myself very clear..... I was referring to circulation of the chlorine throughout the pool. Pools can develop "dead" spots where the water doesn't circulate equally chlorinated water. Drop in a floatie something and see if it finds a calm spot....

Also, check your stairs, light fixtures, etc. for any hidy-holes that the nasties use to avoid your efforts....



- - - Updated - - -

one more thought...

If it were a circulation issue, would I be able to test different areas and see varying FC levels?

In theory? Sure! In practice? It ain't gonna happen....

 

[shawnra]

So did the OCLT and have a couple of observations...

First, at 8 pm FC was 8.5 and CC was 0. At 6 am FC was 7.5 and CC was <0.5 but not 0. So I guess this confirms it is algae and not pollen or something else settling on the bottom.

The interesting thing was that I went to one part of the pool furthest from all of the returns and the FC I read was 1.5 ppm lower than the where I normally take samples. I believe this might support the "poor circulation" diagnosis that folks have suggested here. Given that, who thinks I will be able to get the PB to come back and move some return jets for me?

 

[shawnra]

BTW - has anyone ever used taylor R-7065 standard as a means of verifying test result accuracy? Seems like a good idea but I cant see that you can buy it anywhere other than large quantities from Taylor.

 

[pabeader]

It can be purchased from TFTestkits.net and is used often by many different members here. Do a quick search and you might find a few recent threads.

 

[ping]

I suggest doing the CYA test at the same time as your pool guy and compare the results. You said he uses the same reagents so the results should be close.

Do you brush the pool weekly?

Work on the circulation pattern, the return eyes should be adjustable.

Bottom line is that there is not enough chlorine for the CYA level. Target a higher FC level and do not let it drop below 6 ppm and see how that works out.

In my experience when I try to keep the FC near the minimum level, my pool gets in trouble and I will eventually need to SLAM. Since I've adjusted my target level up a bit I haven't had any problems. My pool gets more use than most residential pools, wife is in it 8 hours a day, and I flirted with the low end of the FC/CYA chart too often and I found out that my pool can not be near the low end of the suggested ranges.

 

[Catanzaro]

In my experience when I try to keep the FC near the minimum level, my pool gets in trouble and I will eventually need to SLAM. Since I've adjusted my target level up a bit I haven't had any problems. My pool gets more use than most residential pools, wife is in it 8 hours a day, and I flirted with the low end of the FC/CYA chart too often and I found out that my pool can not be near the low end of the suggested ranges.

Why is that? If the FC level falls below that 7.5% of CYA, is it that there is not enough unbound chlorine available in the pool water removed all the "bad stuff", or could it be just experience from so many successful pool owners over time? I am also assuming that once the pump shuts off, this could be another issue. One could run the pump 24/7 and possibly keep minimums lower, but that would not make sense as your electricity bill will be very high. Most people stare at me when I explain to them what my levels are daily. Then again, they usually shock the pool weekly, therefore increase the chlorine level, which essentially is spiking your chlorine levels and allowing it to burn off over time.