How much chlorine do I need to kill algae, given these parameters?

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Good job on so much progress!

Don’t forget to scrub the skimmer thoroughly including removing the foam on the weir door and checking behind it. I found spots on the backside of mine when I finally figured out how to get the door out and check. I don’t know if they were algae or not, but the foam got a good soaking in bleach overnight.
 
What I found in my experience with black algae parallels yours.. I think it is more important to brush the algae to disrupt it protective coat.. that exposes it to your CL... I don't think it has a high tolerance to CL hence the ability to eradicate it with your normal target FC. .. at least that is they way I've seen it work in my pool. BUT if you have black algae there may be other types lurking.. so a SLAM is insurance.
Well done SirLead!
PM me when you are ready to retrofit your pool with a SWG.. so you go traveling.;)
 
mguzzy said:
What I found in my experience with black algae parallels yours.. I think it is more important to brush the algae to disrupt it protective coat.. that exposes it to your CL... I don't think it has a high tolerance to CL hence the ability to eradicate it with your normal target FC. .. at least that is they way I've seen it work in my pool. BUT if you have black algae there may be other types lurking.. so a SLAM is insurance.
Well done SirLead!
PM me when you are ready to retrofit your pool with a SWG.. so you go traveling.;)
Click to expand...
I think the most important thing is having a proper test kit. Had I had a proper test kit to begin with, I think it would have been gone long ago, with just a simple brushing! Amazing what the proper FC level can do. ;-)

A friend of mine tore his SWCG out saying it was a PITA! I didn't ask at the time, but now I wonder why, and will ask him.
 
Hi Neighbor!
I wanted to jump on here to comment on a few things.

This has turned into a huge post (sorry) so the TL;DR is this:
El Dorado Irrigation District
See my black algae
FC loss is less with solar cover on, in a normal pool OVERNIGHT loss should be zero.
Daily dosing or near daily dosing is NOT that hard, takes all of 30 seconds for me.
Cold water=less/no algae
Skip Walmart bleach, go to HD and get their Chlorinating Liquid

And the long story:
Because I will be re-filling a newly re-plastered pool soon I recently started researching how much that pool fill was going to cost me. I'm in Sacramento county, but in Antelope, so my water service is Cal-Am. They had a calculator on their website to estimate what your bill would be at different usage rates. If you take a look at your county's irrigation district website they have an estimator too, and I would call and confirm that before you do it, but it doesn't look high to me AT ALL. Here is the link for that specific web page: El Dorado Irrigation District

So, when we bought our pool we knew it would need to be replastered in the near future. We got through almost 3 seasons of swimming before we decided to pull the trigger. In that time, we were dealing with increasingly more stubborn black algae which was taking root in all the pitted areas, and even kind of up under the plaster in some spots (probably hollow spots?) so it was impossible to be rid of completely. So, if you are starting to deal with the same thing you might want to start thinking about a replaster soon. If you need some referrals for our area message me and I'll give you a couple names.
If you want to see the black algae issues I was dealing with look at my pictures here: Small pool reno
You can clearly see how the black algae made its way under layers of plaster and showed as gray areas in the white plaster.

Another couple things I wanted to say...in the absence of green algae or other organics my pool would lose somewhere between 1-2 ppm of FC in a 24 hour period (the black algae never seemed to effect FC loss for me) in the summer. Because I kept a solar cover on pretty much all summer long, UV didn't have much effect. At a CYA level of about 40-50 (I always have a hard time reading that dang dot). For me that translated to about 2 cups to 1 quart of liquid chlorine a day in my ~14k gal pool. Because my pool was like clock work, I could get away with dosing it every 2 or 3 days, as long as I accounted for those missed days. PH and TA was stable so I got pretty lazy with testing those, but even when I did, they were still right where they should be.

Also...in the winter, your water gets really cold...if I understand correctly algae doesn't like water below 60 degrees, which is why I rarely have to add LC in the winter.

I get my liquid chlorine at Home Depot (Home Depot calls it "Shock Treatment"). A 2 Gallon case is $6 something, and that is 10%. Oh, and heads up, HD had 5 day old LC yesterday in Antelope. I don't know if it's already been said in this thread, because I haven't read it all, but I'm pretty sure that Walmart bleach is the same as Clorox in that they have started adding gunk to it that we don't want in our pools.
 
MrLeadFoot said:
...

A friend of mine tore his SWCG out saying it was a PITA! I didn't ask at the time, but now I wonder why, and will ask him.
Click to expand...
Yeah... I would be curious why he tore it out... It was the best thing I ever invested in.. I added one to my 90's era pool in 2005 and haven't looked back since. The cost of the chlorine you save versus the cost of putting it in is really a wash, but the time I save managing my pool was a real surprise. That more than paid for itself in the first year. It took me a while to figure out the idiosyncrasies and chemistry.. and that was before I found this place that had it all laid out already. So when you are ready.. start a new thread in the SWG forum and you will have more help than you know what to do with......;)
 
ManiacalMama said:
Hi Neighbor!
I wanted to jump on here to comment on a few things.

This has turned into a huge post (sorry) so the TL;DR is this:
El Dorado Irrigation District
See my black algae
FC loss is less with solar cover on, in a normal pool OVERNIGHT loss should be zero.
Daily dosing or near daily dosing is NOT that hard, takes all of 30 seconds for me.
Cold water=less/no algae
Skip Walmart bleach, go to HD and get their Chlorinating Liquid

And the long story:
Because I will be re-filling a newly re-plastered pool soon I recently started researching how much that pool fill was going to cost me. I'm in Sacramento county, but in Antelope, so my water service is Cal-Am. They had a calculator on their website to estimate what your bill would be at different usage rates. If you take a look at your county's irrigation district website they have an estimator too, and I would call and confirm that before you do it, but it doesn't look high to me AT ALL. Here is the link for that specific web page: El Dorado Irrigation District

So, when we bought our pool we knew it would need to be replastered in the near future. We got through almost 3 seasons of swimming before we decided to pull the trigger. In that time, we were dealing with increasingly more stubborn black algae which was taking root in all the pitted areas, and even kind of up under the plaster in some spots (probably hollow spots?) so it was impossible to be rid of completely. So, if you are starting to deal with the same thing you might want to start thinking about a replaster soon. If you need some referrals for our area message me and I'll give you a couple names.
If you want to see the black algae issues I was dealing with look at my pictures here: Small pool reno
You can clearly see how the black algae made its way under layers of plaster and showed as gray areas in the white plaster.

Another couple things I wanted to say...in the absence of green algae or other organics my pool would lose somewhere between 1-2 ppm of FC in a 24 hour period (the black algae never seemed to effect FC loss for me) in the summer. Because I kept a solar cover on pretty much all summer long, UV didn't have much effect. At a CYA level of about 40-50 (I always have a hard time reading that dang dot). For me that translated to about 2 cups to 1 quart of liquid chlorine a day in my ~14k gal pool. Because my pool was like clock work, I could get away with dosing it every 2 or 3 days, as long as I accounted for those missed days. PH and TA was stable so I got pretty lazy with testing those, but even when I did, they were still right where they should be.

Also...in the winter, your water gets really cold...if I understand correctly algae doesn't like water below 60 degrees, which is why I rarely have to add LC in the winter.

I get my liquid chlorine at Home Depot (Home Depot calls it "Shock Treatment"). A 2 Gallon case is $6 something, and that is 10%. Oh, and heads up, HD had 5 day old LC yesterday in Antelope. I don't know if it's already been said in this thread, because I haven't read it all, but I'm pretty sure that Walmart bleach is the same as Clorox in that they have started adding gunk to it that we don't want in our pools.
Click to expand...
Thank you for all this, especially since I just switched from Walmart Bleach to Leslie's Chlorine (slightly less money). I had no idea that Home Depot carried LC, and it's 1/2 the price of Walmart bleach and Leslie's chlorine, too!

The problem with daily dosing is that you have to be around to do it, even if it were to take 1 second, you'd still have to be present. I wonder what pool service companies do, since they only visit people once a week. Do they rely on CYA-laden pucks?

I would like those replaster referrals, as my I've been in this house for 20 years, and the house is 27 years old. And, I'm pretty sure the pool went in with the house, so a replaster is a near-future need anyway, if not an overdue need.

As far as overnight loss, goes, I seem to be doing something wrong. I have not gotten a consistent loss reading AT ALL! I do understand that the overnight loss would be different when you the chlorine is battling contaminants like black alage, and getting up to the proper balance, but I really didn't have that much algae. For example, the pool now has no visible algae at all, and according to my testing this morning, lost 3.5 overnight. Previous night loss was only 1.5. Although I am testing at night at least 2 hours after adding LC with the pump on, I think it's too soon, and is not mixed properly, giving me a false reading. Is there an ideal time to wait to test after adding? For what it's worth, I've had my solar cover on this entire time when dealing with the algae, or should I say while getting my pool into the right balance for the first time, which is really more like what I've been doing. I know now that I really did nothing special for the black algae, other than brush it, as I didn't really get that high over my target FC level. But, could having the solar cover on after dosing inhibit the mixing of the newly added chlorine into the water? Also, when I test in the morning, the pump has been off for hours. I do reach down to capture water samples from as far down as my arm will go, which I think is between 18 and 24 inches. What else might I be doing wrong?
 
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pool services jack up the CL levels too high in hopes it will make it a week. When we had a pool service as a kid the rule was no swimming in the pool for 6hrs after he dosed it with CL Gas.

So are you doing the Overnight Chlorine Loss Test per protocol? or just checking a 24 hour range. If you really want to see if you got all the Algae you need to test your FC during a time frame when there will be no other contributing FC losses, ie due to sunlight. So if you keep your cover on during some days that will affect it. The OCTL test you test after the sun goes down and then again before when the sun comes up. If there is any CL loss when comparing the results of those two tests then its likely due to algae.
 
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MrLeadFoot said:
Thank you for all this, especially since I just switched from Walmart Bleach to Leslie's Chlorine (slightly less money). I had no idea that Home Depot carried LC, and it's 1/2 the price of Walmart bleach and Leslie's chlorine, too!

The problem with daily dosing is that you have to be around to do it, even if it were to take 1 second, you'd still have to be present. I wonder what pool service companies do, since they only visit people once a week. Do they rely on CYA-laden pucks?

I would like those replaster referrals, as my I've been in this house for 20 years, and the house is 27 years old. And, I'm pretty sure the pool went in with the house, so a replaster is a near-future need anyway, if not an overdue need.

As far as overnight loss, goes, I seem to be doing something wrong. I have not gotten a consistent loss reading AT ALL! I do understand that the overnight loss would be different when you the chlorine is battling contaminants like black alage, and getting up to the proper balance, but I really didn't have that much algae. For example, the pool now has no visible algae at all, and according to my testing this morning, lost 3.5 overnight. Previous night loss was only 1.5. Although I am testing at night at least 2 hours after adding LC with the pump on, I think it's too soon, and is not mixed properly, giving me a false reading. Is there an ideal time to wait to test after adding? For what it's worth, I've had my solar cover on this entire time when dealing with the algae, or should I say while getting my pool into the right balance for the first time, which is really more like what I've been doing. I know now that I really did nothing special for the black algae, other than brush it, as I didn't really get that high over my target FC level. But, could having the solar cover on after dosing inhibit the mixing of the newly added chlorine into the water? Also, when I test in the morning, the pump has been off for hours. I do reach down to capture water samples from as far down as my arm will go, which I think is between 18 and 24 inches. What else might I be doing wrong?
Click to expand...
I'm not sure why you aren't getting consistent fc readings but perhaps I can shine some light into your fc testing. The scoop with the powder is very important and I've proven this myself a while back after I was having inconsistencies. The blue scoop for the powder develops a crust, and when you fill it and dump it, in essence you not using enough because with the crust still sticking to the inside of the scoop and it's using up the space for the right amount. So #1 would be the make sure the blue scoop is clean. Also the chlorine vial with the label will get coated from the inside with use and rinsing doesn't always get it clean. As mentioned here on the forum once, to rinse it out with alcohol and then with water to eliminate side issues with the test outcome. I once thought my regents weren't good anymore when they were practically new, contacted TFT and the alcohol was my answer.
 
MrLeadFoot said:
With respect to FC loss, when is the best time to run the pump? Overnight, or during the day? Or, does it matter?
Click to expand...
During an OCLT the pump should be running.
15-30 minutes after addition of chlorine is usually enough to get a well mixed sample to test the chlorine level. But it does need to run continuously until you collect your morning sample.
 
MrLeadFoot said:
I have those standard big "normal" lights that look kind of like the old round car headlights. Any idea how to remove them?
Click to expand...

There should be a single screw that when removed the light pops out of the niche.

If the light ash not been removed in a long time that screw can become difficult to remove. If you break the screw or strip it note that it is a special screw. There is a product called Light Wedge if the screw hole becomes stripped.
 
MrLeadFoot said:
Thank you for all this, especially since I just switched from Walmart Bleach to Leslie's Chlorine (slightly less money). I had no idea that Home Depot carried LC, and it's 1/2 the price of Walmart bleach and Leslie's chlorine, too!

The problem with daily dosing is that you have to be around to do it, even if it were to take 1 second, you'd still have to be present. I wonder what pool service companies do, since they only visit people once a week. Do they rely on CYA-laden pucks?

I would like those replaster referrals, as my I've been in this house for 20 years, and the house is 27 years old. And, I'm pretty sure the pool went in with the house, so a replaster is a near-future need anyway, if not an overdue need.

As far as overnight loss, goes, I seem to be doing something wrong. I have not gotten a consistent loss reading AT ALL! I do understand that the overnight loss would be different when you the chlorine is battling contaminants like black alage, and getting up to the proper balance, but I really didn't have that much algae. For example, the pool now has no visible algae at all, and according to my testing this morning, lost 3.5 overnight. Previous night loss was only 1.5. Although I am testing at night at least 2 hours after adding LC with the pump on, I think it's too soon, and is not mixed properly, giving me a false reading. Is there an ideal time to wait to test after adding? For what it's worth, I've had my solar cover on this entire time when dealing with the algae, or should I say while getting my pool into the right balance for the first time, which is really more like what I've been doing. I know now that I really did nothing special for the black algae, other than brush it, as I didn't really get that high over my target FC level. But, could having the solar cover on after dosing inhibit the mixing of the newly added chlorine into the water? Also, when I test in the morning, the pump has been off for hours. I do reach down to capture water samples from as far down as my arm will go, which I think is between 18 and 24 inches. What else might I be doing wrong?
Click to expand...
I'll send you those referrals.

So, ok I think you have solved why you are having the test inconsistencies...That water needs to be mixed up really well before grabbing a test sample. Here is my routine:

My pump is set to run 7am to 12pm (those times specifically so I can avoid the higher tier of SMUD's rates). I usually go grab my sample between 9am and 10am, therefore the water has been mixing for about 2 or 3 hours.

I take my test bottle, peel back a corner of the solar cover near a return, grab some pool water, rinse the sample bottle out, dump it, then turn the bottle UPSIDE DOWN, dunk my arm down as far as I can without getting my clothes wet, turn bottle right side up and grab water from as far below the surface as my short little arms will allow. I know it sounds like a lot, but it isn't, it's super quick.

I then test for FC. If FC is under 10 I then test PH too. I tend to run my FC higher, around 10 (this gives me a lot of wiggle room for those days I either forget to dose the pool or the days where I can't or don't wanna). I'm pretty lazy about testing and would only test about once a week because my pool seemed to be a very habitual creature and liked to lose about 1.5 ppm FC a day unless we had a high bather load or it was uncovered all day. BUT you need to get to know your pool and what its habits are before you do it that way. Which means you need to get it STABLE.

I then pour in a quart of LC slowly in front of a return with the pump running (thanks 7-Eleven Big Gulp cups!), it still has 2 or 3 hours to get nice and mixed up. If I'm running an OCLT I will manually run the pump for a couple of hours in the evening after sun is off the pool, take a reading, then do the same in the morning before sun hits the pool. But you DO need that water mixed up well before you grab a sample. Chlorine likes to concentrate in pockets here and there in still water. I can actually see it when I first remove my solar cover.

As far as daily dosing, yes I know what you mean, you have to be there, but if you can learn the habits of your pool, and establish a routine, you can maybe eventually get to a point where you're safe to dose every 2 or 3 days. The last time I went out of town for 4 days I just brought the pool up to SLAM and covered it. I tested it when I got back and it was still above the "target" for my CYA.

Which brings us to another point...your CYA. That's one big reason to bring your CYA to a manageable level; if you run it at 30 or 40, you can safely throw some pucks in a floater while you're gone without worrying about it driving your CYA up too high.

Did you happen to look at that link I gave you for El Dorado Irrigation District?

And yes, pool services throw pucks in a floater which is why most people that come on here after recently taking over their pool find that their CYA is off the charts. Just like when I took over my pool. When we bought this house and pool I hired a guy, I kept him for a month and a half and then politely fired him, I figured I can screw up my own pool for FREE, what's the point in paying him to do it???

Sorry I got so long winded again...o_O
 
Thanks to all who chimed in on the testing issue. I am indeed doing it overnight, after the sun leaves the pool in the evening, and before it hits the pool the next morning. My dipper is clean (get your minds out of the gutter). :eek:

I think the chlorine is not consistently mixed in well when I test. You see, in the midst of my algae eradication process, I ran the pump for 24 hours. This means that regardless of evening or morning test, the water was always being agitated. Once I resumed normal pump operation, the first evening test was with the pump running, and the subsequent morning test the pump had been off for hours. But, then I changed the time cycle of the pump, and while it is always on when I did the evening test a couple of hours after adding chlorine, the amount of time the pump was off prior to the morning test could very well be what's making the difference. Maybe there's scientific theory to contradict that, but what else could explain that, when my 24 hour loss tests that have always been performed when the pump's been running, are starting to yield more consistent results?

Before anyone gets their panties in a bunch over my last statement, accoring to what I have read (and everything on the internet is true), chlorine can separate from water. Combined with the fact that I have to run much more chlorine than the average CYA pool, and that I keep a cover on the pool, I think it's a good bet that when the pump is off for a considerable amount of time, there is bound to be different concentrations of chlorine in different areas of the pool.

I do not want to run my pump 12 hours to ensure proper mixture to span morning and night tests, so I'm going to stop obsessing about what the overnight loss really is. Regardless of my limited experience with the TFP method of balancing a pool, I think I've had a pool long enough to know when something is off simply by looking at it. Isn't that why God, or whoever you believe in, invented algae that survives in pools, and particulates like phosphates that cloudy waters; so we can easily see when something is amiss? :unsure: I will just monitor 24 hour periods for now to find my pool's nominal daily loss, and balance from there.

I wonder if my high CYA, and the subsqently higher amount of chlorine I must ensure is mixed into my pool, contributes to the inconsistent test issue. I will be checking with local my Water Nazis when I get back from my trip. Thank you, maniacalmama, for doing the initial leg work for me on that. Sine you're so good at things like that, when are you coming my to help with my daily dosing? :sneaky: Oh, and for what it's worth, longer posts are more helpful than short ones sometimes. As you can tell by my posts, verbosity is king.

Regarding my question about when to run the pump, what I meant was, are there better times to run the pump to help with minimizing chlorine loss? For example, does running it during the daylight hours cause chlorine to be higher in the water column, or something, and thus more easily burned off, in which case it would better to be run the pump at night? Or, does mixing into the water help keep it from being burned off, thus be better for the pump to be run during the day? Or, does it even matter?
 
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The time of day you run the pump is based on skimming needs and electricity costs. You also need to run the pump at least 30 minutes after adding chemicals.
 
ajw22 said:
There should be a single screw that when removed the light pops out of the niche.

If the light ash not been removed in a long time that screw can become difficult to remove. If you break the screw or strip it note that it is a special screw. There is a product called Light Wedge if the screw hole becomes stripped.
Click to expand...
OK, I will look CLOSELY at the crew before doing anything. Assuming there is algae behind the lights, what would happen if I left it there? If I keep my FC where it's supposed to be, wouldn't that at least prevent it from getting into/onto anything else?
 
mknauss said:
The time of day you run the pump is based on skimming needs and electricity costs. You also need to run the pump at least 30 minutes after adding chemicals.
Click to expand...
So, what you're saying is that there's no science behind WHEN to run the pump to prevent chlorine loss.

As I mentioned, I wait 2 hours after adding chemicals before testing, but what about what I said about morning tests, when chemicals are not added? That seems to be where the tests fluctuate a LOT!
 

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