Quick Slamming Questions - Mustard Algae

[Chat]

So half the summer, here I am thinking I have more pollen settling into my pool than normal. Finally now that summer is almost over I start thinking about it and doing some research only to realize it's mustard algae. I've done a baqua conversion so I'm down with the SLAM process but I have a quick couple of questions.

CYA - 30
PH - 7.5
FC - 30 (only needs to be 19 according to chemgeek's chart)
CC - 0

In my haste to get this going, I misread the MA SLAM directions and I went straight to the MA shock level. I didn't start it until about 6PM my time. I don't need to stay at the normal SLAM level for 24 hours provided I pass my OCLT in the AM, right? The part I need to stay at SLAM level for at least 24 hours is the MA SLAM...at least, that's what I think.

Basically, I want to count tonight as my normal SLAM even though my FC is higher than 12. My plan now is to stay at MA shock level (assuming I pass OCLT tonight) until at least Saturday morning (assuming I pass OCLT Friday night) and then let my FC come back down.

Next question, I'm leaving my wife in charge of the process for the handful of hours I'm at work tomorrow. She was a chem major (for a year) at college so she's capable but we have three small children. Can I bump the FC up a little higher than normal to give her a buffer? The only downside would be a) cost of the chlorine and b) time it takes to get the FC back to normal, right?

Last question, what percent of my CYA is it okay to let people swim? I know public pools keep their chlorine much higher than we do and the extra chlorine will wear on suits more but when is it not safe?

Ok, maybe not quick questions....sorry about that. Any light you guys can shed on this would be appreciated.

 

[chem geek]

Yes, it's OK you went to the higher SLAM first, but I wouldn't drop to a regular SLAM until you're sure you've killed off the yellow/mustard algae so you shouldn't see it growing and it may be bleached out (more gray than colored). Don't forget to brush and get behind light niches or under removable ladders if you have any.

Yes, you can bump the FC to have a buffer. Going higher within reason is not a problem.

We normally say it's safe to swim below SLAM level. You are right that even at yellow/mustard SLAM levels the active chlorine is not much different than some commercial/public pools with no CYA since it's roughly equivalent to around 1.4 ppm FC with no CYA. However, we don't normally recommend using the pool at this level. I wouldn't call it unsafe, but it's a high level of chlorine that is over 20 times higher than our regular minimum FC/CYA level in terms of active chlorine. So one day in the pool is like 20 days in a normal pool and the effects on swimsuits, skin, and hair will reflect that.

However, keep in mind that an extended SLAM especially at elevated levels can have the chlorine oxidize the CYA so your CYA level may be dropping and lower than you think, which would make the active chlorine level even higher. So your best bet is to wait until you've stopped the SLAM. If you've got plenty of CYA reagent you can test for the CYA level, but add some drops (I'd say 5) of R-0007 (sodium thiosulfate) to the water sample (before adding the CYA reagent) to get rid of the chlorine in the water sample since at high levels it can interfere with the CYA test having it read falsely low.

 

[Chat]

It's almost midnight here, I just went out to brush and took another FC measurement. It's down to 27.5 but the CC is 0. At night isn't the only way to lose FC by it eating whatever is in the water but wouldn't that show up as cc? I'm wondering if I mismeasured earlier.

 

[chem geek]

It's down to 27.5 from what? There can be test error of up to 10% though with a relative OCLT test you can be 5% if careful, but at 27.5 that would be +/- 1.4 ppm FC.

If you do have something consuming chlorine it does not necessarily result in CC. Many chemicals can get oxidized without producing CC or they produce it but at too level to show up in the test because the CC is temporary on its way to further oxidation. So we don't consider CC as an expected indicator except when dealing with ammonia because chlorine reacts with ammonia to form monochloramine that shows up as CC. That's not algae, however,

 

[Chat]

Sorry, 27.5 down from 30. I edited my OP. Ok, so margin of error is +\- 10% but to be conservative on the oclt we'll say 5%.

Maybe I forgot how to count to 60?

I'll retest before sunup and we'll go from there. Thanks for the quick reply.

 

[chem geek]

Also, at higher FC/CYA levels there can be faster chlorine oxidation of CYA so that's chlorine demand as well. So I wouldn't sweat the type of loss you are seeing. We usually do an OCLT at lower levels -- not at a yellow/mustard algae SLAM. So I think you're OK as far as the OCLT goes though you can certainly do it again if you want.

 

[Chat]

Ok, new plan. FC was 25 at 6:30. At 11 it dropped to 18, no cc either time. We're almost at the end of our season so I decided to wait a week before I go through the full SLAM so my kids can enjoy the pool this week since we're due for quite a few 90 degree days. After that, the season is over and I can do what I want and take as long as I need with no pressure.

This will also let me find out how much of my CYA was oxidized.

Thanks Chemgeek, I'll let you all know how it goes. I'll take a few pics also since there seems to be a lot of posts about pollen vs MA.

 

[Chat]

I passed the normal SLAM last night (took two days) and am moving on to the MA level slam. Two questions:

1. I have an AG pool and can't take out the light without lowering the water level under the opening which would mean I can't filter, how would I clean in and around it like I've seen suggested to others?

2. I have wedding cake steps which have holes in the tubing to allow water in to decrease buoyancy. There is also sand in there to increase the weight. Obviously there is no circulation in it, if I take it out of the water would the MA die over the winter? Our season here in NY is over and the winters get pretty cold. Short of me filling the steps with straight bleach after it drains I don't see many options.

Thanks in advance.

 

[Chat]

I'm doing the MA slam right now. The article I read stated it should be done for 24 hours. This morning my CC was 1.5.

Obviously I should continue until I pass an OCLT, right?

Cya - 40
pH - 7.3
FC - 26
CC - 1.5

 

[Texas Splash]

Good morning Chat. It looks like you haven't received a reply in a few, so I'd like to address a few things. The first thing I would caution or ask you about is .... did you truly pass your original SLAM a week ago? That has to happen first before starting the MA boost. You must have passed all 3 SLAM criteria, one of them of course having <= .5 ppm of CC. Only then do you increase to MA level. It sounds as though you need to let your FC go back down to the regular SLAM/Shock level and continue until you pass all 3 criteria.

While at the regular SLAM level, that's the best time to complete one of those items - the OCLT. If you try it at MA level, it may be confusing because when your FC level it that high, it's not uncommon to lose more than 1ppm of FC overnight. Trust me, I learned that from personal experience the hard way.

As for your wedding steps - very common issue. If there is any way to remove them and inspect and/or clean I would suggest doing so. All of those kind of items (steps, ladders, etc) that are filled with bricks, sand, etc, become a haven for algae. So if you can remove the step, I would do so before it gets too cold up there.

As for the light, you may be forced to wait until you close when you do in-fact drop your water level. I'm not sure you have any other option.

But for your CC to be elevated right now, your bleach is processing too much organic material. Something may still be in there which is why I asked about the success of your previous SLAM.

 

[Chat]

Thanks for the quick response.

I actually removed the steps Friday and started the normal SLAM process over. It took me a few days to pass it, yes, I'm sure I passed all 3 steps as the 2nd to last night was borderline so I went the extra day just to be sure.

The odd part was that I met the other two OCLT criteria except for the cc. Is that even possible?

Will the cold kill the algae inside the steps? If I closed it now would it kill what's in there? I'm in NY so the winters can be pretty cold.

 

[Texas Splash]

Some others may confirm the cold water question (killing algae), but I don't believe the cold water actually kills the algae, it just slows it down or perhaps makes it go dormant. When the spring returns, it will flourish with vengeance. There's a method to the madness when using all 3 criteria, because there are times when one still remains, even though the water is clear or passes another part of the test. Something is still being processed, oxidized, or filtered. So if you still have more than .5 of CC, I would continue the SLAM until that number stops going over .5. Ensure everything is good now to make the spring opening that much easier on you.

Great call on the steps and SLAM by the way!

 

[Chat]

I don't think I was clear in my last question. If my cc is over 1 shouldn't the FC have dropped because the cc is used up FC? My FC was the same but the cc was over 1.

 

[Texas Splash]

One of the others may clarify more, but I would say there are variables that can effect the timing of your FC and CC. For example, let's say you have some FC being converted to CC awaiting oxidation. So now your CC is slightly elevated. Depending on when you tested (early am, or cloudy day perhaps) the CC may not have been able to be oxidized by the sun, yet you may have added a little bleach. If you didn't add bleach, some of the FC got used, but hasn't yet been burned-off. That's just one example I could think of. I suspect there are others that others can expand upon.

Conversely, (FYI) we often see when someone is SLAMming a really green pool that their FC is very high, and CC low to zero, all because of timing and it hasn't begun to transition yet.

 

[Chat]

Ok, so I tested it this morning, it was barely light out and the CC was 1.5. I got home and tested again (FC - 20, CC - 1.5), it was decently sunny for most of the day. My wife added once during the day.

I guess I'm asking, if I passed the OCLT after the normal SLAM, does it matter that my CC is this high now with the MA SLAM? Am I supposed to be at the MA SLAM level for only 24 hours or am I passing another OCLT? My brain says that if there is CC there it's because the FC is fighting something so I shouldn't let my foot off the pedal.

 

[Texas Splash]

You're right about not letting off. But you don't need to do it at MA level past 24 hrs, and there is no additional OCLT during a MA SLAM, so that won't be an issue. I'm more concerned with that cc that continues to be slightly elevated. Going back to what you said early this morning in post #11 that has me confused:

Yes, I'm sure I passed all 3 steps as the 2nd to last night was borderline so I went the extra day just to be sure. The odd part was that I met the other two OCLT criteria except for the cc. Is that even possible?

If you passed all 3 criteria of the SLAM, I don't understand the last part of that quote, "odd part ...... met the other two OCLT criteria except for cc". Sorry if I'm not understanding what you did. You passed a SLAM, held it a 2nd night to be safe, but still have elevated cc's right? So if that's true, then all I can surmise is that the SLAM really isn't finished. You have clear water, you passed an OCLT (maybe twice), but your cc is still elevated. Am I understanding that correctly?
At the very least, with a CYA of 40 from post #9, that means you should maintain the traditional SLAM/Shock FC level of 16. I would keep it there until your cc readings drop to .5 or less. At that point if you want to do another OCLT you can, but I wouldn't bother exhausting yourself with that until the cc is under the .5 mark. I hope this helps and doesn't seem frustrating. The last part of a SLAM certainly can be, especially when everything is so darn close except for one reading. If I mis-read something in your notes or you still have a questions, please let me know.

 

[Chat]

That's just me being unclear.

The first part about doing the SLAM for the extra day was referring to my regular SLAM. Which passed the OCLT.

The sentence that starts with the 'odd part' was referring to my first night of MA SLAM. I wasn't understanding no FC loss but 1.5 CC.

Basically, the cc was 0 during my regular SLAM but has been 1.5 twice now during the MA SLAM which I took to mean the FC was working on the MA.

Apparently that might not be the case and I shouldn't have even checked the CC at MA SLAM levels since it sounds like it's irrelevant.

Thanks for your quick response, btw.

 

[Texas Splash]

That does make a lot more sense now.

Apparently that might not be the case and I shouldn't have even checked the CC at MA SLAM levels since it sounds like it's irrelevant.

I would agree. Have a nice evening.