Let me also note, in case this changes your answer, I have an in-ground spa that uses the same water/pipes/pump system as my pool. So I'm not sure if that means I should get either of these in check (water is not that cheap right now either where I'm at). I know with a higher TA, the more aeration I have in the spa, the higher the pH can go. And the higher the pH, the more likely the higher CH will cause scaling, correct?
Algae issues and chlorine problems
- Thread starter ndakotaninja
- Start date
Let me also note, in case this changes your answer, I have an in-ground spa that uses the same water/pipes/pump system as my pool. So I'm not sure if that means I should get either of these in check (water is not that cheap right now either where I'm at). I know with a higher TA, the more aeration I have in the spa, the higher the pH can go. And the higher the pH, the more likely the higher CH will cause scaling, correct?
You are correct. Also note that higher temperatures also raise CSI.
The good news is that running the return through the spa with all the jets and aeration going can really raise the pH back up in a hurry. So if you choose to aggressively lower the TA, the process is really fast.
- May 22, 2013
- 2,796
- Pool Size
- 12000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
"I've had my filter/SWG (at 100%) running 24/7 for the last 7 days or so."
I'm not sure but during the SLAM shouldn't the SWG be off
I'm not sure but during the SLAM shouldn't the SWG be off
If the point is to raise and keep the chlorine levels up, then having the SWG only helps (and reduces the amount of shock I have to put in, saving me money). Nothing in the SLAM instructions said to have it off, only to turn it off when performing the OCLT (overnight test).
I'd run your CYA test again just to be sure the level is 20. If it is actually higher, you'll need a higher level of FC for the SLAM. If it actaully is 20, then there is nothing wrong with bringing it up to mustard level for an OCLT and see. Be sure to run your filter during the OCLT but not the SWG. You are still losing quite a bit of FC to something and will need to continue to SLAM unitl you pass the OCLT.
Looks like you are doing everything right though, just need some POP (Pool Owner Patience)
- May 22, 2013
- 2,796
- Pool Size
- 12000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
I didn't know, just something I thought I had read.
I did a search . . . it looks like there are good reasons to turn it off : http://www.troublefreepool.com/threads/65719-SLAM-with-SWG
Running it at 100% is hard on the unit and I'm pretty sure most would agree cuts down it's life. Compared to just adding a $2.50 jug of bleach you might want to reconsider turning it off or down some.
I did a search . . . it looks like there are good reasons to turn it off : http://www.troublefreepool.com/threads/65719-SLAM-with-SWG
Running it at 100% is hard on the unit and I'm pretty sure most would agree cuts down it's life. Compared to just adding a $2.50 jug of bleach you might want to reconsider turning it off or down some.
I did my CYA test before I started and it was 20. I tested it again the next day and it was still that low. In fact I was adding the solution to the tube and while it was cloudy and partially obscured the black dot, it never went away. As to the POP, i agree with you, some things just take time. I'm just concerned that it's been 5+ weeks now of water that's clear and inviting and yet not safe to swim in. I wasted 3 weeks dealing with the pool store as they got me to use $40 of chemicals to fix it. Despite me saying i didn't think it'd be enough, that I needed to raise the chlorine more than that, they convinced me to go the cheaper route first. A week later, it was $80 of chemicals. A few days later, $130 of chemicals, including the strongest algaecide they had. At least at that point it killed what looked like all of the algae (stopped getting small clusters of algae growing on the walls, stopped seeing dead algae scum on the surface of the pool and in the skimmers, and stopped seeing the slimy white stuff on the tiles of the pool). Yet the chlorine level in my pool continued to drop to zero indicating something in there is still using it up (besides the sun).
I'm fine waiting if that's what I really need to do, but I also don't want to do the 'spend $60 on bleach and spend a week of electricity running the system and my time' only to find out that I actually should have been doing it more aggressively. I'd prefer to get it all done at once rather than play the waiting game and potentially end up spending more time and money doing it a second time at a higher level because the first wasn't good enough, right? And again, my reasoning for this is it did seem to be mustard algae I was cleaning up after we used the strong algaecide, and everything seems okay with the pool except that my chlorine levels keep dropping, even though everything looks clean and clear. So there's got to be something using it up that the high level of chlorine isn't properly sanitizing.
As to the SWG, seems it can go both ways. I will probably turn it down to 60% or so, but not off, just to maintain a steady amount of chlorine into the pool. I'd also probably be a good experiment, since I'm doing tests about every 2 hours while I SLAM it, to turn it off and see how much the FC goes down with it off versus with it on. It'd give me a sense of confidence that it's working properly/well.
I think someone may have already mentioned this but do you have any lights? If you do, have you pulled them out and cleaned them and the light niche? Algae likes to hide out in there and eat up chlorine and mess up people's OCLT! Also under or behind any ladders or any hidey holes that might be in there...
Yes, I pulled out the light in the pool and it was really gross. I cleaned it as best that I could and I left the light out so hopefully the bleach/circulation will clean out anything that I couldn't get to. Is there anything special I should do for that area? Or is that enough?
So I've noticed that my FC changes quite a bit depending on where I take my water sample from. I've been using the same spot every time so I get consistent readings, but yesterday I tested it in a different location and found the FC was only 3ppm. I took it from my regular spot and it was 7.5ppm. It's a fairly large pool and there's only 2 returns, so it seems there gets a lot of dead spots that don't get good circulation and therefore don't necessarily get properly sanitized.
So I'm wondering if maybe the water circulation could account for why the FC continues to drop despite not seeing algae anymore? Is there a preferred direction to point the jets in a rectangular pool to better circulate the water? I have my deep end jet pointed straight to the shallow end, and my shallow end towards my deep end. So the areas of water directly to the sides of my jets seem to be the problem areas (arrows are jet directions and x are areas that always seem to have low chlorine). I'm wondering if maybe I should point the jets more to the left to get water flowing in a sort of clockwise direction around the pool?
Deep end
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| v @@@ x |
| v @@@a |
|@@ ^ @ |
|x @ ^ a@ |
|x @. @ xx|
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shallow end
So I'm wondering if maybe the water circulation could account for why the FC continues to drop despite not seeing algae anymore? Is there a preferred direction to point the jets in a rectangular pool to better circulate the water? I have my deep end jet pointed straight to the shallow end, and my shallow end towards my deep end. So the areas of water directly to the sides of my jets seem to be the problem areas (arrows are jet directions and x are areas that always seem to have low chlorine). I'm wondering if maybe I should point the jets more to the left to get water flowing in a sort of clockwise direction around the pool?
Deep end
------------
| ' @@@xx |
| v @@@ x |
| v @@@a |
|@@ ^ @ |
|x @ ^ a@ |
|x @. @ xx|
------------
shallow end
Last edited:
- May 22, 2013
- 2,796
- Pool Size
- 12000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
There are more questions on jet direction than good answers. Normally you want to aim them so they circulate water but also help move surface debris towards the skimmers. During a SLAM you want to have the best circulation. It's also why sweeping is recommended, it gets the water all stirred up 
plus helps with filtering too.
It's a matter of trial and error. Which ever way keeps the most water moving is best.
plus helps with filtering too.It's a matter of trial and error. Which ever way keeps the most water moving is best.
So I'm getting a little antsy. I've been SLAMing my pool for a week now. I stopped seeing any visible algae (like on the ladder or in nooks and crannies) after 2 days, I've stopped seeing dead algae (clumped up on the floor of the pool like dust bunnies) after 4 days. My CC for the last 4 days has been 0 or .5 consistently. So for the last 3 nights I've tried doing the OCLT. All 3 nights my FC has dropped from 10 to ~5. I've seen no improvements in the pool for the last 4 days, and the water still looks clear and clean, pretty much the same as it did when I started trying this process.
So I guess I'm wondering if there is something else I should be doing, or another reason there could be for the drop in FC each night. That's been my only problem this whole season really, is that my FC drops every day. When I was keeping it around 3 after I opened the pool, it kept dropping down to 0, allowing the algae to grow in the first place. Now I'm keeping it around 10 and it's still dropping. So is there something I should be looking for to measure any improvements? Is there another test I could try to see if I actually have algae still? I can keep it up, but only so long I'd like to continue this if I'm seeing absolutely nothing change.
So I guess I'm wondering if there is something else I should be doing, or another reason there could be for the drop in FC each night. That's been my only problem this whole season really, is that my FC drops every day. When I was keeping it around 3 after I opened the pool, it kept dropping down to 0, allowing the algae to grow in the first place. Now I'm keeping it around 10 and it's still dropping. So is there something I should be looking for to measure any improvements? Is there another test I could try to see if I actually have algae still? I can keep it up, but only so long I'd like to continue this if I'm seeing absolutely nothing change.
Yes, there was quite a bit of dead algae that was in there that came out. The dead stuff got vacuumed up when I vacuumed that morning. The rest got mixed in and filtered out. When I brush I continue to brush in there too, just to kinda wash it out in case anything is still growing in there. I also scrubbed the ladders/railings, the intakes to the skimmers, and all the walls/floors/stairs of the pool (I do those daily). There originally was a slimy whitish algae that was visible on the ladders/skimmer intakes, but again, I haven't seen any of that anywhere in the pool since 2 days into the SLAM.
As a side note, when I first started, there was the clumps of dead algae on the bottom of the pool in the mornings that looked like dirt/dust bunnies, I haven't seen those since Saturday morning. When I brushed, there also used to be dust clouds that would rise up and turn the pool cloudy, so much so that it could be hard to see the bottom drain. Now when I brush I get some sediment, but it seems to just be normal dirt (it doesn't cloud the water, there's not very much of it, seems to be things like chips off of the plaster pool).
Discussing it with my SO, I was thinking maybe my OCLTs are being affected by my connecting spa (not shown in the picture above). I have the line connecting the two open right now to allow water to flow back and forth between them and keep the water levels even. During the day I usually run the 2 together to circulate the water some, and then shut the spa back off. I figure tonight I could close off the line between them and see if the pool FC continues to drop. When I'm testing the water, I've only been testing the pool water, not the spa, so it could be the pool is fine, but something's going on with the spa. If anyone else has thoughts or things to try, let me know. Both the pool and spa look clean and again, not seeing any live or dead algae for the past few days.
One final thing: If my CYA is 0 (as opposed to the 20 we're assuming), would that change the levels of FC needed to kill the algae. Last month I did put 16lbs of it in, and I used about 20 lbs of the granular shock which has CYA in it as well. And yet, every time I've tested it (or the pool store tested it), it was like 0-20. Right now when I do the test it gets a little cloudy, but I run out of my solution and I can still make out the black dot. So the lowest CYA on the tube is 20, but it seems to be lower than that. Should I try raising the CYA to make the shocking more effective? Also, what would cause the CYA to lower, especially 16+lbs in a matter of 2-3 weeks?
As a side note, when I first started, there was the clumps of dead algae on the bottom of the pool in the mornings that looked like dirt/dust bunnies, I haven't seen those since Saturday morning. When I brushed, there also used to be dust clouds that would rise up and turn the pool cloudy, so much so that it could be hard to see the bottom drain. Now when I brush I get some sediment, but it seems to just be normal dirt (it doesn't cloud the water, there's not very much of it, seems to be things like chips off of the plaster pool).
Discussing it with my SO, I was thinking maybe my OCLTs are being affected by my connecting spa (not shown in the picture above). I have the line connecting the two open right now to allow water to flow back and forth between them and keep the water levels even. During the day I usually run the 2 together to circulate the water some, and then shut the spa back off. I figure tonight I could close off the line between them and see if the pool FC continues to drop. When I'm testing the water, I've only been testing the pool water, not the spa, so it could be the pool is fine, but something's going on with the spa. If anyone else has thoughts or things to try, let me know. Both the pool and spa look clean and again, not seeing any live or dead algae for the past few days.
One final thing: If my CYA is 0 (as opposed to the 20 we're assuming), would that change the levels of FC needed to kill the algae. Last month I did put 16lbs of it in, and I used about 20 lbs of the granular shock which has CYA in it as well. And yet, every time I've tested it (or the pool store tested it), it was like 0-20. Right now when I do the test it gets a little cloudy, but I run out of my solution and I can still make out the black dot. So the lowest CYA on the tube is 20, but it seems to be lower than that. Should I try raising the CYA to make the shocking more effective? Also, what would cause the CYA to lower, especially 16+lbs in a matter of 2-3 weeks?
Have you brushed the spa?
Recommended SLAM is 10FC up to 25CYA.
Have you replaced a significant amount of water (backwashing)?
Recommended SLAM is 10FC up to 25CYA.
Have you replaced a significant amount of water (backwashing)?
I don't think you want to raise the CYA past 30 yet... taking it to 30 probably wouldn't hurt but AFAIK it would only reduce your daytime bleach consumption not make the SLAM more effective.
Your comments about widely different FC levels in different parts of the pool sound like a useful clue. I would definitely try adjusting the eyeballs to get as much of a "whirlpool" as you can, and angled down a bit as well.
As others have mentioned, brushing a lot helps big time with circulation issues.
Your comments about widely different FC levels in different parts of the pool sound like a useful clue. I would definitely try adjusting the eyeballs to get as much of a "whirlpool" as you can, and angled down a bit as well.
As others have mentioned, brushing a lot helps big time with circulation issues.
I brush the spa daily along with the pool. The water in it is just as clear as the pool. My CYA I assume is 0, so I didn't know if I should get it to 20 to get more accurate SLAM results. The only water I've replaced is what's evaporated during the last week (I think it rained for about 20 minutes a few days ago, and it's been sunny and hot the last week, so the water has lowered about 2 inches over the last week. Cartridge filters, so I don't backwash it.
I'm closing off the spa line for tonight to see if it helps. I'm going to test things again overnight and see if I get the same results or if it improves with this change. If it doesn't, I'll readjust the eyeballs. I'd be curious if it would help to test a lower-reading section of the pool instead and raise it to 10FC instead. It would mean that some sections of the pool would be at 15-20, but at least all of the water would be at least 10FC.
- May 22, 2013
- 2,796
- Pool Size
- 12000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
If you are getting different FC readings in different parts of the pool you need to wait more between adding and testing and you need to brush to stir it up. It might be that your algae problem is actually a poor circulation problem.
From your description, you have some CYA (because the test is cloudy) but less than 20 - if it were truly 0, it wouldn't turn cloudy at all.
It is recommended to have a minimum CYA20 during SLAM to ensure the chlorine doesn't get burned off as much due to the sun - CYA doesn't affect OCLT, however you can raise it by about 5ppm to reduce FC loss during the day.
CYA does not go down through evaporation - as water evaporates CYA gets more concentrated until water is added back.
Any thoughts why my CYA would be reading so low? In late May I added 14lbs. 2 weeks after that, they said it was reading 0, so I added the 2lbs I had left. I also was shocking with granular shock, so it should have added more. Does algae use up/eat away CYA? Does another chemical I could have added lower it as well?
I ran the OCLT last night with the spa closed off and it went from 10FC to 7.5FC again. I'm testing the water from the same spot every time to get consistent results, sometimes every 2-3 hours, sometimes every 6 or so (depending on my schedule). I'm brushing at least once a day, sometimes twice (or if I get a weird reading, i brush, wait a few minutes, and re-test but it has still read the same, so I know it's just actually low). I'll adjust my eyeballs today and see if that helps. But again, it doesn't look like I have any algae issues, so it's obviously frustrating to have the test keep telling me something is wrong. Should I clean out the filter before doing the OCLT? Maybe the dead algae on the cartridges are causing problems?