Startup SWG chlorinator salt for new pool

[Dirk]

It would probably be enough to have a big pool party, FC dropped due to bather load, and the algae took over, suddenly creating high chlorine demand.

That's how I got my one-n-only patch of algae since starting TFP care. Ruined my perfect record! I got a bit lazy with testing, so I didn't notice low FC, then had a bunch of kids in the pool. Next day, the green monster. Not bad though. I goosed the FC a bit high and brushed and that was it. Sort of a mini SLAM. But I learned a good lesson, and where my pool's "algae theshold" is...

 

[FIESTA62]

recommend to SLAM

hi, ok i read how to slam seems straight forward, but i had a look at the stain patch, i last looked last weekend, pool has had cover on this week as usual, i just peeled back cover and stain is still there but really its pretty faint, i scrubbed last week but it didn't all come off, but i can see its got no worse, i am happy to slam if that's what you advise
but see pic i attached, i know u cant see the stain in pic so i outlined it just so u know the area, it is too faint to get a decent pic , bottom line yes its there , but is it really bad enough to slam?
or is slamming a good idea now and then to give pool a real clean sparkle again....although its looking pretty good now, i got pool at FC6 now and hope to maintain now i have a better understanding

 

[Dirk]

Are you leaving your pool covered for days at a time? For a whole week? I don't know much about that, or if that encourages algae or not, because I don't cover my pool. Buy I know you're supposed to let them breath. I think every day. Others here will know more about that.

 

[mgtfp]

Really faint, I see what you mean. But you are sure that it's algae? It reacted to brushing, algae-like texture, not just some sort of stain?

Put it like that: The SLAM is an established process that will work.

But you are right, that shadow is hardly recognisable, and your OCLT is in spec. Dirk's mini-SLAM might do, bump the chlorine a bit higher, above non-SWG target and keep it there. Brush daily until the stain is gone, maybe then another OCLT at the elevated chlorine level. That can work, might take a bit longer. But if it's not gone in a week, I'd upgrade to a real SLAM.

With chlorine it's all about Chlorine Contact Time (CT), chlorine level multiplied with contact time. When your FC is half of SLAM, it will take double the time to clear the same mess (as long as the chlorine is high enough (and maintained high enough) to kill faster than the critters reproduce). SLAM is designed to clear up an algae infestation reasonably fast while still being able to use the pool.

 

[FIESTA62]

let them breath

its covered whenever i am not using it, on average its covered say 5 days at a time, could be a week, i read somewhere about chemicals build up gas and can damage pool , some say when u leave on for too long when removing you can smell the vapours of chemicals escaping, i have never noticed that, i called daisy pool covers they are the leaders in pool covers, they say once a month, but really they push keeping water balanced more than worrying about pool cover,

i dont get many leaves but when i do they sit on cover and generally blow and move to the corners of pool or sides, i then use a dust pan and broom and sweep them off cover, as cover on top is mostly dry its easy, and when i mow grass some gets onto cover same thing i sweep it off, so the cover has its uses...

 

[FIESTA62]

you are sure that it's algae

well when i first spotted stain over a week ago it looked green, not bad but was there, i brushed and about 80% gone, 1 week later its the same no worse, i had a look just now its a faint hint of green, i gave it a scrub and its looking better but still there, i will watch it closely , i am thinking with a few more brushes and keeping FC up it should be good, i did let FC drop to 3 for a bit wont do that again.....i am testing morning and night till i get FC6 minimum steady......thanks

 

[FIESTA62]

if it's not gone in a week, I'd upgrade to a real SLAM.

hi, well i been tested morning and night, last night 6pm it was FC9 pretty high , but this morning at 8am its FC7. i tested again just to be sure and yep FC7, i am pretty careful with my testing, full drop keeping it all the same, same amount of power etc, so its a big drop overnight , unless i somehow messed up with the FC9 result but i doubt it
ok so pulled cover back this morning and that stain is still there but has grown, now about 1 metre long by about 200mm, but very faint i didnt see it at first look but now i do its obviously grown, we had a few cloudy days and i wonder as i have my heat pump on keeping pool at around 29C and pool cover is on, maybe blanket is not letting direct sun thru enough and helping to promote Algae
anyway i am thinking maybe i better do the slam, i see at FC6 slam level is FC31, how do i know when its slammed enough? do i just watch stain and soon as i see its gone give it a few more hours then stop the slam? as said its still a faint stain so i assume wont take long to fix

 

[aussieta]

slam has 3 criteria to finish

SLAM - Shock Level and Maintain

We’ve all had to deal with a green pool. Clear algae from your pool with a SLAM! Read here to use shock level and maintain to clear your pool.

www.troublefreepool.com

 

[mgtfp]

last night 6pm it was FC9 pretty high , but this morning at 8am its FC7.

Technically, it wasn't a real OCLT because the evening test was before sunset and the morning test after sunrise, but the UV in these hours should be too low to explain 2ppm loss. And with the stain growing rather than shrinking, SLAM is in order.

Make sure to read the article that aussieta quoted first and follow all steps.

 

[FIESTA62]

yep it was before sunset but it was a cloudy day not sunny at all and bit of rain too, i did do it a bit late in morning but only a touch pool was still shaded, but i get your point i was outside the correct times to do test, it does seem a big drop at FC2,
i will start slam tomorrow, just want to do another overnight test today just to check ....

 

[Dirk]

Yep, you got the green. SLAM away. Others have pointed you to the directions and to look for the part about the criteria to determine when you're done.

One of the most important parts of the SLAM is the "M," as in Maintain. You can do a sloppy SLAM, but it'll just take longer. The more you keep your FC from dropping even a little below your SLAM level, the faster it'll go. Every time you dip, you might add a little time until you're done. Dip a lot, and you'll be starting over.

I just wanted to double check on something your wrote: "I see at FC6 slam level is FC31." Your SLAM level is based on your CYA level, not your previous FC level. I can see where that FC/CYA chart can be misleading. Even though the Targat FC column is just to the left of the SLAM column, you want to look all the way over to the CYA column. That's what determines your SLAM level.

 

[FIESTA62]

look all the way over to the CYA

yep i looked at chart, my CYA at last recent test is 80 or 90, 80 is extremally faint, i got to really stare to see that dot, or at 90 its defiantly gone, but really 80 is very close, so 80/90 cya.....chart says target 6 for 80 cya, slam 31

i will target 6 , i been getting 7 or 7.5 as i am still tweaking and tested more, but from what some have said 1 or 2 above is ok, so i guess the 7 or 7.5 i have been getting is ok, although i got FC9 last night not sure about that so more testing to be done

apart from that i left cover off today, had a nice sunny day i got in pool gave stain a scrub and really its hard to see now its there but really got to stare, wife actually could not see it at all, this morning in the shade i could see it faintly, but in full sun this afternoon it was a struggle to see it, pool looks crystal clear, so more tests and watching stain just not sure about if slam is really needed, more tests !

 

[mgtfp]

i will target 6 , i been getting 7 or 7.5 as i am still tweaking and tested more, but from what some have said 1 or 2 above is ok, so i guess the 7 or 7.5 i have been getting is ok, although i got FC9 last night not sure about that so more testing to be done

There is no harm in having FC a bit higher than target. You will loose a bit more chlorine per day (the UV-loss is a percentage of the FV-level), i.e. the SWG has to work a bit harder to maintain the higher level. But that's about it, swimmers won't notice a difference. 9 is still the lower target range for a non-SWG pool, absolutely fine to swim in, costs you a bit more daily chlorine production.

Especially while you are still tweaking things, it gives you a bit more buffer to the min level. Once you have it all worked out, you'll see which individual target works best for you, so that even after a few really sunny days, lots of swimming, maybe a duck family dropping their load, and not getting around to test FC, you won't drop below min-FC. Much easier to go through that learning curve with a bit more buffer.

Maybe you'll see that the actual SWG-target from the table works well for you, that will certainly be the most economical level from a chlorine production point of view. But if that means that under your personal boundary conditions (UV-load, bather-load, leaves, duck-poo, work-load - which can affect how often you realistically manage to test your water -, etc.) you run the risk of dipping below min-FC, then it's perfectly fine to just choose a higher personal target-FC.

And once you find the right settings to keep FC constant through really sunny days, those settings will let your FC rise a bit when you get a few cloudy days. No harm in that, once it's sunny, FC will come down again. If it stays cloudy, you might adjust the SWG eventually. But frankly, it just increases the risk that you forget to dial the SWG up again once the sun is back.

But for now, it's time to SLAM...

 

[mgtfp]

Just read that in another thread:

Mistake I made were trying to keep FC at the min..Worked for a while until we have pollen and rain and then had to SLAM. Now I just keep it at 7

Does this sound familiar? Find the FC-target that works for you.

 

[FIESTA62]

Find the FC-target that works for you.

ok i get it, but i often think i get it and later find out i don't know what i am doing ! i have learnt more today, i said stain is pretty much gone , i check in sun in afternoon it looked good, but i just checked at 7pm full shade and the stain is worse, it goes about 2 metres from the corner of pool in both directions, so its about a 4 metre long stain, its faint yes but clear enough to see, but i even called the missus down to show her i am not going nuts, its there

so i learnt stains are more easy to see in shade not sun, or thats in my case, so slam starts tomorrow morning

but i have a question on CC test, i did the FC test at 7pm it is 6.5, was 7 this morning , so lost 0.5 during the day, but then i did the CC test, using the 10ml sample, i put the 5 drops in and the FC sample turned pink, i then put 1 drop in to test and it went clear straight away so i figure CC is 0.5, then after about 45 seconds the sample went pink again huh ?
ok put another drop in sample went clear , i think ok all good then its CC 1, but same deal 45 or so seconds later it goes pink again, i put another drop in, and another, another etc, now at 14 drops sample keeps turning pink after about 45 seconds, so looking at CC 7, i gave up at that point

do i go by the test at the first drop it goes clear instantly , and it does stay clear for a while, but i assume wait longer and see , i did not wait on previous tests, i just seen clear and usually tipped in sink after a few seconds, not realising i should wait longer, so it looks like the CC is 7 plus.....

 

[mgtfp]

It is normal that the water turns slightly pink again after a while, whether it's the FC or the CC test. First clear turning is the endpoint.

That's why it's important to work reasonably fast when testing for FC. And don't wait for too long after finishing the FC test before adding the CC drops, or you'll always think that you have CC.

 

[FIESTA62]

First clear turning is the endpoint.

oh that's good news, that's why i gave up at 14 drops it kept turning pink ( slightly pink ) but took at least 30 or say 45 seconds, the first drop stayed clear for about 30 seconds i guess, so then my CC is 0.5 good news, slam in morning...thanks again, i owe you and the other legends on here big time....

 

[Dirk]

mgtfp's got you. FC and CC test results are what happens right away, before it turns pink again. CC is a byproduct of the FC chewing on your organics (sweat, bird poop, leaves, pollen, etc, whatever gets into your pool, and in your case your algae). If you think of chlorine "eating" the unwanted stuff, then think of CC as chlorine's poop. (That's not what's happening, exactly, but that's how I remember it.) So even when your algae is gone, expect to sometimes see CC, and sometimes not, because sometimes chlorine has something to eat, and sometimes it's done eating everything. That's normal.

Some algae can be stubborn, it builds up a protective "candy shell" that resists chlorine. So that's why you SLAM and brush. The brushing helps break down the shell, and the elevated chlorine does the rest. You've obviously got a resistant patch, so that's why we're calling for the SLAM. If it was just a hint of algae that developed from a one-time FC drop, returning to target FC might have taken care of it. But because it's still lingering, it's not that, it's the tough stuff. So you gotta get tougher...

 

[FIESTA62]

ok so i have started slam, i went and bought chlorine from the pool shop and it does have a date stamp jan 20th i think , so all good, it was fc 30 last night, i put in the recommended dose plus a bit extra to get to FC 35, i am using 90 cya as my level, test this morning FC 26.5,
pool math says put in 2.5 litre to target FC35, i put in 5 litre , yes twice as much , is it a problem if i go over like this? 2 x i have put in what pool math says but did not get to target so i did the extra this time

 

[FIESTA62]

forgot to mention when at pool shop buying chlorine they said use a ALGAECIDE, i didn't buy any as not wanting to keep dumping various chemicals into pool if i don't need to, i figure the slam should do the job, but if it is a good idea to use algaecide i will buy some