- May 3, 2014
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Algaecide - Further Reading
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Startup SWG chlorinator salt for new pool
- Thread starter FIESTA62
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ok i figured you all would say that as u never mention algaecide, all good i will keep the slam going.........
And don't go over the slam purposely by a lot because it's just wasteful and won't make it work faster.
i wouldnt usually go over, but the math didn't get it to target on my first 2 attempts, so on 3rd attempt i added more than math suggested, but my end aim is to get it to FC35 , not over, i just want to get there, i will give it another hour or so to circulate and retest
The main part is keeping it at slam level and not letting it drop back too far. As the FC loss becomes less and less then you know things are in your favor. When you no longer have any FC loss I'd go it two more days with slam and then do OCLT. Call it done when all 3 criteria have been met.
- Mar 5, 2020
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Regarding Algaecide: There are only two scenarios where an Algaecide can make sense: When closing a pool for winter (in Australia we tend to keep pools open over the relatively mild winters in most major cities), or when having to leave the pool for longer periods of time without chlorine additions (e.g. holidays with a manually chlorinated pool - with a SWG you should never have that scenario). And then the only Algaecide that TFP recommends is the Polyquat60 (sold under different names down here) as described in Marty's link.
Certainly no copper based algaecides, as that will create a copper staining problem down the road. But that's exactly what pool shops usually recommend to clear a green pool. Copper is quite effective in killing algae, but it's just not worth the consequential risks down the road - you'd trade in an algae-green pool against a copper-green pool.
Other, cheaper non-copper based algaecides, don't work very well to start with, make your water foam and your pool smell horrible.
Polyquat60 like Algaecides (quite pricey) work reasonably well in preventing algae in situations as mentioned above where min chlorine levels can't get ensured. They are completely unnecessary when sticking to the FC/CYA-table.
Polyquat60 is not good at killing already existing algae, and is actually contra-productive during a SLAM as it gets oxidised by chlorine, i.e. you will loose additional chlorine "fighting" the Algaecide.
Regarding overshooting SLAM-FC: We certainly don't recommend to swim above SLAM-FC. You also have to remember that the further away from target-FC you are, the faster you loose chlorine to UV-breakdown. It just becomes very un-economical to overshoot too much, as you are just fuelling UV-losses. SLAM-FC is a good compromise between fast algae kill-times and reasonable UV-losses.
But I don't think you'd do any harm to your pool. I like to put things into perspective like that: Pool shops consider FC 3ppm without any CYA to be perfectly acceptable. Well, depending on your actual pH and whether your CYA is actually closer to 80 or 90, the "active" chlorine concentration (i.e. the part of FC that is not bound to CYA) of FC 3ppm with no CYA is roughly equivalent to about FC 50-60ppm in your pool with CYA. You can draw your own conclusions from that...
[EDIT] Or look at it the other way round: At pH 7.5, FC 35 @ CYA 90 is equivalent in active chlorine concentration to FC 0.63 @ CYA 0. [/EDIT]
But it doesn't make much sense to go that high, as you will loose a lot of that "excess" chlorine to UV. It will cost you a lot more chlorine with only little added value.
Going too far above SLAM-FC can also result in unnecessarily high pH while at high FC (adding chlorine raises pH, the following use of chlorine reduces pH again - the chlorination-cycle is pH-neutral). That could create metal staining should metals (e.g. from the use of Algaecides) be in the water, or worsen a calcium scaling problem for those with high CH.
Certainly no copper based algaecides, as that will create a copper staining problem down the road. But that's exactly what pool shops usually recommend to clear a green pool. Copper is quite effective in killing algae, but it's just not worth the consequential risks down the road - you'd trade in an algae-green pool against a copper-green pool.
Other, cheaper non-copper based algaecides, don't work very well to start with, make your water foam and your pool smell horrible.
Polyquat60 like Algaecides (quite pricey) work reasonably well in preventing algae in situations as mentioned above where min chlorine levels can't get ensured. They are completely unnecessary when sticking to the FC/CYA-table.
Polyquat60 is not good at killing already existing algae, and is actually contra-productive during a SLAM as it gets oxidised by chlorine, i.e. you will loose additional chlorine "fighting" the Algaecide.
Regarding overshooting SLAM-FC: We certainly don't recommend to swim above SLAM-FC. You also have to remember that the further away from target-FC you are, the faster you loose chlorine to UV-breakdown. It just becomes very un-economical to overshoot too much, as you are just fuelling UV-losses. SLAM-FC is a good compromise between fast algae kill-times and reasonable UV-losses.
But I don't think you'd do any harm to your pool. I like to put things into perspective like that: Pool shops consider FC 3ppm without any CYA to be perfectly acceptable. Well, depending on your actual pH and whether your CYA is actually closer to 80 or 90, the "active" chlorine concentration (i.e. the part of FC that is not bound to CYA) of FC 3ppm with no CYA is roughly equivalent to about FC 50-60ppm in your pool with CYA. You can draw your own conclusions from that...
[EDIT] Or look at it the other way round: At pH 7.5, FC 35 @ CYA 90 is equivalent in active chlorine concentration to FC 0.63 @ CYA 0. [/EDIT]
But it doesn't make much sense to go that high, as you will loose a lot of that "excess" chlorine to UV. It will cost you a lot more chlorine with only little added value.
Going too far above SLAM-FC can also result in unnecessarily high pH while at high FC (adding chlorine raises pH, the following use of chlorine reduces pH again - the chlorination-cycle is pH-neutral). That could create metal staining should metals (e.g. from the use of Algaecides) be in the water, or worsen a calcium scaling problem for those with high CH.
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As far as I know we don't use algaecide for vacations. We would recommend to over chlorinate before and have some floaters and maybe a good neighbor look after it some.
- Mar 5, 2020
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- Astral Viron V35
I would always recommend what you described. I only said that it "can" make sense to use Polyquat60 during holidays, i.e. when no one could be found to top up chlorine to ensure FC not dropping below min. It certainly is no guarantee to prevent an algae bloom, but it might buy some extra time. Preferred option is always to keep FC high enough. But there are situations where that's not possible.
I really only wanted to highlight that there are not many situations where Algaecides are even worth thinking about - and these don't even apply to the OP's situation with a SWG and a warm climate where closing for winter is uncommon.
- Nov 12, 2017
- 12,662
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- 12300
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- Pentair Intellichlor IC-40
DO NOT use any algaecide. That will mess with the pool. SLAM is all that is needed. (Algaecide is pool store mumbo jumbo.)
Don't go over SLAM level:
- It'll just waste chlorine. It won't get you to the end of the SLAM any faster.
- It could harm pool equipment.
- It's safe to swim in a pool up to SLAM level, but not over.
Edit: Oops, for some reason none of the above posts were visible when I replied. Everybody covered everything well.
Don't go over SLAM level:
- It'll just waste chlorine. It won't get you to the end of the SLAM any faster.
- It could harm pool equipment.
- It's safe to swim in a pool up to SLAM level, but not over.
Edit: Oops, for some reason none of the above posts were visible when I replied. Everybody covered everything well.
- Nov 12, 2017
- 12,662
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- 12300
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- Pentair Intellichlor IC-40
Did anyone mention? pH drop testing is not reliable over FC 10, so don't bother until your SLAM is over.
Did you remember to drop pH to 7.2-7.5 before you started the SLAM?
Did you remember to drop pH to 7.2-7.5 before you started the SLAM?
ummm no, but tested PH a few days ago it was 7.5, but i am having a problem here i cant get to FC35
my recent cya test that i did a few days ago and i did a few times to be sure and it was 80/90, i am going on cya 90, so slam is FC35, this morning at 8am i had FC 26.5, pool math says add 2.5 litres to get to FC 35, i added 5 litres , twice as much as pool math says, so would assume it should hit FC 35 no problem, well its 3.30 pm here just tested i got FC 22 huh what going on its dropped even after 5 litres added, its a mild sunny day nothing crazy hot
i got new chlorine from pool shop yesterday
now pool math says add 3.8 litres to get to FC 35, but from my experience so far i know that's not going to get to FC 35, since starting yesterday i have put a total of 22 litres in pool
so pool math says add 3.8 litres, sitting at FC22 now, should i do that or just add more like say 6 litres to hopefully get to FC 35
mguzzy
Gold Supporter
My goodness.. must you be so scatological?
I learned the algaecide dance the hard way... SLAMing is the way to go. And if you did dump an algaecide in there.. all your hard earned FC would like go poof. Most of them react with the algeacide and you are back to square one. As mgtfp says... about the only good use for for algaecides is when closing your pool.
- May 3, 2014
- 62,717
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- 6000
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- Pentair Intellichlor IC-40
Read the SLAM Process. You test and add liquid chlorine every couple hours at the start. Do not add liquid chlorine to go above your SLAM level. The chlorine will not be protected by the CYA and will disappear quite quickly due to sun on the pool. Air temperature has little to do with chlorine dissipation.
hi, i read and it says... "Test and adjust chlorine levels as frequently as practical, but not more than once per hour, and not less than twice a day " , i am very low on chlorine regent , ordered more yesterday, so are conserving, testing for FC35 uses a lot, but i been testing morning and night as math suggested, at minimum i realise that, when new regent arrives a can test more often
so as you suggest i should test every 2 hours,
so i should go and add exactly what pool math says 3.8 litres, then test in 2 hours, is 2 hours really enough for the chlorine to fully circulate thru the entire pool ?
i usually run my pump at a slower speed at 1600 rpm, but to do this process i guess i should ramp speed up a bit to say 2400 rpm thats mid range speed on my pump
- May 3, 2014
- 62,717
- Pool Size
- 6000
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- Fiberglass
- Chlorine
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- SWG Type
- Pentair Intellichlor IC-40
The chlorine will circulate in 30 minutes or less. Brush the pool after adding to move the chlorine throughout the pool quicker.
I was just suggesting you need to test and add more than once or twice a day to start.
Use 5 ml water sample and each drop of reagent to clear is 1 ppm FC. Only do that while in SLAM. Go back to normal testing for OCLT.
I was just suggesting you need to test and add more than once or twice a day to start.
Use 5 ml water sample and each drop of reagent to clear is 1 ppm FC. Only do that while in SLAM. Go back to normal testing for OCLT.
ok i learn more again, i was thinking add more chlorine to get to the FC35 target quicker, but now understand the extra is just not protected by cya, that makes sense, wow there is so much to learn
and what this 5ml sample ? never heard about that, that would help during the 2 hour testing save a bunch of regent, i did not know i could do that, i got new regent arriving tomorrow , i will use the 5ml test till i get stable at FC 35, ok i will test more often, 4pm here will test at 6pm, then 8pm if i still have regent......thanks
- Nov 12, 2017
- 12,662
- Pool Size
- 12300
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- Plaster
- Chlorine
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- SWG Type
- Pentair Intellichlor IC-40
Yep, you got it now. I think you were getting to 35, and probably above. The extra burned off fast, and the rest during the day. Not just due to the sun, but the algae, too. You can satisfy yourself that you're getting to 35 by testing again within 30 minutes (that's not necessary, just if you're curious). But if the chlorine is fresh and you're confident with your water volume number, then you're likely hitting the target.
You'll go through a lot of chlorine and reagent at first. Once the algae starts dying, you'll need less chlorine to maintain 35 and you'll be able to test less often.
Remember, I told you that if you shortcut the process, you'll just stretch out the time the SLAM will take. By testing first at 8, then only again at 3:30, your FC dropped significantly in that 7.5 hours, which really lessens the affect of the chlorine on the algae (whether you meant to or not). So that just stretched out the timeline. The more you can keep the FC at 35, not above, and not below, the faster the process will go, which means the less chlorine you'll need and the less reagent you'll use...
You'll go through a lot of chlorine and reagent at first. Once the algae starts dying, you'll need less chlorine to maintain 35 and you'll be able to test less often.
Remember, I told you that if you shortcut the process, you'll just stretch out the time the SLAM will take. By testing first at 8, then only again at 3:30, your FC dropped significantly in that 7.5 hours, which really lessens the affect of the chlorine on the algae (whether you meant to or not). So that just stretched out the timeline. The more you can keep the FC at 35, not above, and not below, the faster the process will go, which means the less chlorine you'll need and the less reagent you'll use...
as i have said before i think i know it all, kinda in my head, then wake up to myself and learn more almost every day in this pool stuff.....
- Nov 12, 2017
- 12,662
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
- Mar 5, 2020
- 3,221
- Pool Size
- 66000
- Surface
- Plaster
- Chlorine
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- SWG Type
- Astral Viron V35
Nothing really to be added. I agree with Dirk that you probably got briefly to 35, maybe even above, but the further away from target-FC you are, the faster it gets lost to UV - and the algae will be taking its fare share, too.
If you really want to test how close you get to SLAM, then make sure to add your last chlorine after sunset, and test after 30 min. Without UV-loss, you should get pretty close to 35.
Good suggestion from Marty with the 5ml sample, that saves a lot of reagent during a SLAM - but don't do it for normal testing. Since your CCL FC tube doesn't have a line at 5ml, you can either use a syringe to measure the right amount, or you can use the CCL CYA mixing tube - the first line is at 5ml. Just make sure to give the tube a good clean first, all the milkyness that usually develops in that tube can get cleaned with some bleach. Or, if you have it, the graduated tube that comes with the smart stir.
If you really want to test how close you get to SLAM, then make sure to add your last chlorine after sunset, and test after 30 min. Without UV-loss, you should get pretty close to 35.
Good suggestion from Marty with the 5ml sample, that saves a lot of reagent during a SLAM - but don't do it for normal testing. Since your CCL FC tube doesn't have a line at 5ml, you can either use a syringe to measure the right amount, or you can use the CCL CYA mixing tube - the first line is at 5ml. Just make sure to give the tube a good clean first, all the milkyness that usually develops in that tube can get cleaned with some bleach. Or, if you have it, the graduated tube that comes with the smart stir.