At what temperature does algae start to grow in pool water? Last few weeks zero cl in pool, zero added, water crystal clear? Any problem in just continuing like this until algae does appear and then slam? Seems kind of wasteful to keep adding cl when no one is using the pool and it looks great? Any downside to running cl free?
at what water temperature does algae start to grow in pool water
- Thread starter jb
- Start date
- May 3, 2014
- 58,656
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Algae will be in any pool without chlorine in it. With cold water, it just does not multiply quickly. But once your water gets much above 50F, it will start. Above 60F, it will bloom.
Maintain your FC based on the FC/CYA Levels
Maintain your FC based on the FC/CYA Levels
Well, we had the icemaggedon and still no algae in my pool - crystal clear. I have saved a bit in CL thank goodness. I know spring is around the corner though will be slamming soon...
JB please reconsider. With the lower demands of the off season, you can go days without adding, and only a little when you do. You won't gain much by letting it go until your spring arrives (next week ? Lol). SLAMMING will use alot more effort than just maintaining the pool until it warms up.
My $.02
My $.02
Thanks for the well wishes but I need to slam anyway when I get started since my CL dropped below minimum.
Climates like Florida and Texas do not play. One minute we’re marveling at the lovely cool weather, and the next minute we’re sweating our keysters off and staring with disbelief at a green pool. I would not advise waiting until there is greenage (pop culture reference).
Not when its as cold out as it was, and not without failing an Overnight Chlorine Loss Test or having clarity issues. If you do in fact have a little algae it will be easy to clear if you don't let it fester
Agree with @Newdude . The old saying - you can pay me now or pay me (double) later. You most likely will use a lot more chlorine to slam than to keep it steady now.
mguzzy
Gold Supporter
I don't understand why you would want to play chicken with your FC... there is always algae in your pools water, even when its cold, just waiting for the right conditions for exponential growth. Its the only way it knows how to grow. If there is some FC in there you will suppress the growth when the conditions start to optimize for the algae. There is no reason to SLAM if your FC is in the right range when the temps start to rise... that is unless you just like doing SLAMs for the fun of it.
Disagree, if you let Cl get to low, even if the water is clear, a SLAM is going to be necessary. I think what you are trying to say is if you always maintain your Cl at the correct level, a SLAM will not be necessary. My point is will a SLAM use less CL than treating clear cold water for 2-3 months? If so, seems the better path to choose. Less $, less time, less waste and debris for the environment.
mguzzy
Gold Supporter
I disagree.. we are talking about cold water, yes? if you let the FC drop to 1ppm and the water is in the 40's, and the sun is low on the horizon, as it is in the winter, the combined effect of low indecent light, low temp is going to suppress algae growth enough for it to not make a whole lot difference. But keeping some FC in there is going to help keep things in check. I'm not recommending that, but its possible. The TFP protocol recommends the good ole FC/CYA Levels for your FC level in any conditions, because that is the safer thing to do.. but in reality you can let it fudge in winter when the water is colder and the sunlight is at an angle. And then bring the FC up as the winter months start to wane. If you let your FC drop in the summer... then yeah its a different war.
And it really doesn't take that much chlorine to maintain a little residual FC in those wintry conditions. That is your buffer and the thing you can measure that will tell you the pool is waking up. For me at my latitude that happens in March.. because if I wait until April, I have a green mess. But I can tell you from experience, and I learned the hard way, spring sneaks up on you. In my pre TFP days I tried ignoring the pool in the winter time, I even turned off the pumps completely and figured I would dealt with the green monster come spring. What I learned is it took way more chlorine and effort to resurrect it from a rampant biology experiment than if I spent 10 minutes a week keeping tabs on things in the winter. This year I used all of 3 gallons of chlorine (and some of it was old) to make it through the winter months until the SWG came out of hibernation.
And it really doesn't take that much chlorine to maintain a little residual FC in those wintry conditions. That is your buffer and the thing you can measure that will tell you the pool is waking up. For me at my latitude that happens in March.. because if I wait until April, I have a green mess. But I can tell you from experience, and I learned the hard way, spring sneaks up on you. In my pre TFP days I tried ignoring the pool in the winter time, I even turned off the pumps completely and figured I would dealt with the green monster come spring. What I learned is it took way more chlorine and effort to resurrect it from a rampant biology experiment than if I spent 10 minutes a week keeping tabs on things in the winter. This year I used all of 3 gallons of chlorine (and some of it was old) to make it through the winter months until the SWG came out of hibernation.
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Yeah I hear ya mguzzy. I note you have the SWG which helps also. For the record, I don't do the green swamp either. Still clear as of today. But in December when I was maintaining, still was adding about 3 gallons a week of Cl. It adds up. About to fire it up as I know algae is right around the corner. I stocked up last week. May test my CYA and start this weekend with just maintenance and see what happens. Fully expecting to have to slam at some point though I have two huge liveoaks that drop literally a ton of organic matter into the pool in March.
mguzzy
Gold Supporter
You and I have different pools, obviously and we are in different environs. 3 gallons almost lasted me all my winter. Though I have a SWG, it becomes less effective as the temp drops and shuts down when the temp goes below 50 degrees. At that point I am running like any other manually dosed chlorine pool during the winter. But you are further south, the sun is higher in the sky, and I imagine your water temp is higher too. What are your other chems ( I didn't see any posted) .. CYA would have a hand in CL retention as well the further south one goes where the sun is higher. All those factor into it. As @Newdude suggests a OCTL test is the definitive answer to whether you need to SLAM or not. If you pass that then you probably don't have to SLAM. And without specific test results this is all conjecture.
- Jul 17, 2019
- 3,730
- Pool Size
- 13000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
I am in your climate and agree with mguzzy. While your pool is bigger than mine, I bought 4 gallons of liquid chlorine back in November and still have 1.5 gallons left. Something isnt adding up.
During the crazy weather 2 weeks ago, I added half a gallon once I could get to my water through the ice. My chlorine is still above 8.0, even after we used the spa last night.
Its your pool and you can manage it however you want, but it seems foolish to guarantee you have to SLAM in a few weeks when the water warms up. Even if you have to SLAM, a $4 bottle of chlorine every few weeks between now and then will help keep your algae suppressed and greatly reduce your SLAM time and the chlorine you need to use.
During the crazy weather 2 weeks ago, I added half a gallon once I could get to my water through the ice. My chlorine is still above 8.0, even after we used the spa last night.
Its your pool and you can manage it however you want, but it seems foolish to guarantee you have to SLAM in a few weeks when the water warms up. Even if you have to SLAM, a $4 bottle of chlorine every few weeks between now and then will help keep your algae suppressed and greatly reduce your SLAM time and the chlorine you need to use.
Interesting conversation.. I had a similar thread earlier.
My FC was 0-1 all winter with no pump running and it looked perfect. And when I bumped it up to "2" it never dropped..
I also don't remember a year when my water temp stayed below 50 for months at a time and we haven't had a horrible winter.
My FC was 0-1 all winter with no pump running and it looked perfect. And when I bumped it up to "2" it never dropped..
I also don't remember a year when my water temp stayed below 50 for months at a time and we haven't had a horrible winter.
mguzzy
Gold Supporter
So in my Pre TFP days I used to let the pool go in the winter. The water temp would drop into the high 40's for the Dec-Feb months.. and I figured hey, its too cold to swim in and algae isn't going grow when its that cold anyway. I even turned off the pumps figuring I could save on the e- bill. During the winter the water always looked clear. Well, I was wrong, without exception I always missed the timing of prepping the pool for the swim season.. first I did it in May, nope its green. Then I tried April, nope turned green on me then too.. So I found I need to start paying attention to my pool in early March, any later and I will have a green mess. All this could have been avoided had I applied the concepts I learned as a Marine grad student to my pool... There is ALWAYS algae in the water, and it can grow at any temp! The amount varies, and the rate of growth varies, depending on the conditions but its always there. You said you get a lot of organics from the trees around you.. so do I, and that is the primary source of the nutrients that I have to deal with.
Fast forward to now, I had since added an SWG, but even with that the Dec-Feb months are still the same protocol since it is too cold to produce chlorine. But its not cold enough that I need to "close" the pool. its more of a soft close. And this is what I find I need to do during that time.
1) Get the organic material that drops into the pool out as soon as possible, the longer its in there the more nutrients will leach into the water.
2) I can reduce my pump run time, but I can't turn it off. The circulation is filtering particulates nutrients. Same with the pool sweep.
3) Maintain some kind of chlorine level. Yeah the conditions are on your side to help suppress the algae growth. but by monitoring the FC I can see when the pool starts to "wake up". I find it to be a combination of the sun getting higher in the sky and the temp of the pool starting to go up. During the winter I only test once a week or every other week since there is not a lot going on in the pool. It hardly takes any time, but this was a huge help to see when the FC demand starts to go up as the season changes. If I had been doing some basic winter testing back in early days I would have seen when the pool was waking up and could have responded accordingly, instead of play Algae roulette. If you are going through that much chlorine in the winter.. there is something going on in your pool.
4) I let my residual CYA level from the summer ride out during the winter. It has less of an effect when the sun is not as high in the sky... and with the trees around my pool it hardly gets any direct sun anyway, but there is some in there. The rainy season here is pretty predicable, For the most part its usually done by March and any rain we get after that I typically won't have to drain the pool to accommodate. That is when I start adding CYA because I know I won't be draining off any water, and coincidentally it corresponds with the sun getting higher in the sky. I start by bringing the CYA up to manual dosing levels on the FC/CYA Levels and by April I am up to the SWG dosing levels as the SWG is able to handle the FC load.
5) With all the organics I get in the water from garden runoff (the backdrop of my pool is a raised garden area) and tree snot, I find a phosphate treatment helps with that. This is a point that is up for much debate here, since technically if there is no algae then there should be nothing to eat the phosphates. but I find it helps limiting at least that nutrient chemical, so I use it as a part of my opening procedure and then I am done with it. Also there is some anecdotal evidence it makes SWG's run better. The jury is still out on that. Those discussions are scattered around the forum.
Well this turned into a longer post than I thought but the take aways are don't assume there is nothing going on in your pool when its winter, there is. Testing is important even to confirm nothing has changed. Just saying, "hey its clear" and going about your day I find will come back to bite me in the butt.
Fast forward to now, I had since added an SWG, but even with that the Dec-Feb months are still the same protocol since it is too cold to produce chlorine. But its not cold enough that I need to "close" the pool. its more of a soft close. And this is what I find I need to do during that time.
1) Get the organic material that drops into the pool out as soon as possible, the longer its in there the more nutrients will leach into the water.
2) I can reduce my pump run time, but I can't turn it off. The circulation is filtering particulates nutrients. Same with the pool sweep.
3) Maintain some kind of chlorine level. Yeah the conditions are on your side to help suppress the algae growth. but by monitoring the FC I can see when the pool starts to "wake up". I find it to be a combination of the sun getting higher in the sky and the temp of the pool starting to go up. During the winter I only test once a week or every other week since there is not a lot going on in the pool. It hardly takes any time, but this was a huge help to see when the FC demand starts to go up as the season changes. If I had been doing some basic winter testing back in early days I would have seen when the pool was waking up and could have responded accordingly, instead of play Algae roulette. If you are going through that much chlorine in the winter.. there is something going on in your pool.
4) I let my residual CYA level from the summer ride out during the winter. It has less of an effect when the sun is not as high in the sky... and with the trees around my pool it hardly gets any direct sun anyway, but there is some in there. The rainy season here is pretty predicable, For the most part its usually done by March and any rain we get after that I typically won't have to drain the pool to accommodate. That is when I start adding CYA because I know I won't be draining off any water, and coincidentally it corresponds with the sun getting higher in the sky. I start by bringing the CYA up to manual dosing levels on the FC/CYA Levels and by April I am up to the SWG dosing levels as the SWG is able to handle the FC load.
5) With all the organics I get in the water from garden runoff (the backdrop of my pool is a raised garden area) and tree snot, I find a phosphate treatment helps with that. This is a point that is up for much debate here, since technically if there is no algae then there should be nothing to eat the phosphates. but I find it helps limiting at least that nutrient chemical, so I use it as a part of my opening procedure and then I am done with it. Also there is some anecdotal evidence it makes SWG's run better. The jury is still out on that. Those discussions are scattered around the forum.
Well this turned into a longer post than I thought but the take aways are don't assume there is nothing going on in your pool when its winter, there is. Testing is important even to confirm nothing has changed. Just saying, "hey its clear" and going about your day I find will come back to bite me in the butt.
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mguzzy is providing some factual, realistic advice. Grow/no grow is simply not black/white.
Well written mguzzy. Wholeheartedly agree with 1. Removing organic matter from pool as fast as possible. Curious how you missed the timing prepping of your pool when you let it go and got surprised with a green pool. Is it covered? Or not somewhere you don't see it regularly? I walk by mine at least a dozen times a day and its visible from the den and kitchen, so there's no way it could surprise me. I've never had a green pool (18years this year). Up until last year though I used tabs and usually left a few in floaters in the winter at all times and they last a long time in cold water. But then my CYA got out of whack and while I always kept a clear pool, I was using more and more tabs and shock and I just couldn't get rid of some algae on the walls. I'd brush it, shock and a few days later it would be back. then I found TFP (yeay) I had to do a partial drain to lower the CYA and then switched to liquid. First slam I goofed, the second got right. Then all summer, crystal clear AND no algae ANYWHERE. It was awesome. December was warm here and we have deciduous trees so organic matter again, perhaps why the Cl demand was relatively high, but I was still checking Cl daily, so no guessing. I've never done liquid thru the winter, perhaps in Jan if I had of kept checking the demand would have dropped off sharply, I'm guessing that's probably the case. Either way, added 2 gals liquid today. Still crystal clear. I'm kinda busy the next few days, but I'll start maintaining FC and also do a overnight chlorine drop test within the next week. As I agree, without the tests this is indeed all conjecture!
A few comments folks seem concerned about doing a slam or like that's a worst case scenario. I'm thinking our experiences with slamming must be quite different. I've only ever slammed a clear pool because it failed the overnight test or had visible annoying algae. It was relatively easy and didn't use that much CL.
A few comments folks seem concerned about doing a slam or like that's a worst case scenario. I'm thinking our experiences with slamming must be quite different. I've only ever slammed a clear pool because it failed the overnight test or had visible annoying algae. It was relatively easy and didn't use that much CL.