First SLAM - questions

Stooge007

Active member
Jan 10, 2017
28
Sydney, Australia
hi all

wasn't around to check my pool the last few days, and it developed some visible green algae

the water has been and was clear before i started the SLAM, and no other issues

using a clear choice labs test kit

pre-SLAM:

FC maintained around 6-7
CC always < 0.5
CYA 70
pH 7.6

SWG run ~ 6 hours a day @ 60% usually keeps FC stable

so i dropped pH down to 7.2
FC was 6, so added 4800mls of 12.5% chlorine to raise FC by 22 (25K litre pool)
and brushed the spots i could see had growth (brushed from outside the pool)

was running the SWG @ 100% (produces 170g chlorine/6 hours) testing of FC in the first 24 hours has seen FC level increase up to 32 without any addition of chlorine???

about 30 hours into the SLAM and a bit of brushing with a steel brush, FC never dipped below 30, the water was the clearest i've ever seen it

but i had suspicions there was still growth (it's a pebblecrete pool, so 1) it's hard to see what's algae and what's pebble from the surface; and 2) the algae loves to get in between the pebbles), so i jumped in the pool with my snorkel on, and sure enough there were still patches of green

so i got out the steel brush and brushed as much of the algae by hand as i could handle (it was cold, and i didn't want to be in the pool with FC @ 30+ for long)

would 32 hours @ shock level be long enough to start killing the algae? there were definitely some green patches when i looked close up

i tested CYA twice to make sure, as i thought it may be higher than i thought, but tested both times @ 70

seems weird that there was quite a bit of algae when i hopped in and took a closer look, but i haven't had to add more FC since the original lot, just had the SWG running @ 100% and FC level has been steady/increasing (started @ 28, 30, 31, 32, 31)

going through a butt load of the chlorine test chemicals, even using a 5ml sample and counting each drop as 1ppm FC

should i add more FC?

or should i just keep the SWG @ 100% and the pump running for another couple of days?

i would have thought that level of chlorine (despite the CYA level) would smash up the algae, but it seems to settle nicely between the pebbles :(
 

Jezza

LifeTime Supporter
TFP Guide
Jan 18, 2015
969
Bunbury, WA, Australia
Remember a SLAM with visible algae can take at least several days -firstly to get on top of it and then completely kill it off. Algae also loves nooks and crannies. Sounds like you've got a pretty good handle on the process and it was a good idea to get in the pool and brush it by hand to make sure you're getting it. Despite all that- if you still have visible algae it doesn't matter what is happening with your FC, you need to continue the process. Also if your running the SWG 100% then it will be adding FC.

Don't worry about the high FC level - it is safe to swim in up to the SLAM level for your CYA. And if you were having problems seeing it, I'd get in each day just to check and brush any suspicious areas.

I'd also turn off the SWG- mainly to save it but just using liquid chlorine to SLAM gives you an idea of how much FC you are losing. If your confident on your CYA reading stay the course and brush regularly, you should notice a reduction in the visible algae over time.
 

kimkats

Mod Squad
LifeTime Supporter
Jul 10, 2012
37,507
Tallahassee, FL
algae forms a "cover" that protects it from it's killer-chlorine! My guess is you just happened to miss brushing the areas you saw the green in.

I would keep up the SLAM and brushing for a little while longer to make sure you get it all.

Kim:kim:
 

Stooge007

Active member
Jan 10, 2017
28
Sydney, Australia
Remember a SLAM with visible algae can take at least several days -firstly to get on top of it and then completely kill it off. Algae also loves nooks and crannies. Sounds like you've got a pretty good handle on the process and it was a good idea to get in the pool and brush it by hand to make sure you're getting it. Despite all that- if you still have visible algae it doesn't matter what is happening with your FC, you need to continue the process. Also if your running the SWG 100% then it will be adding FC.

Don't worry about the high FC level - it is safe to swim in up to the SLAM level for your CYA. And if you were having problems seeing it, I'd get in each day just to check and brush any suspicious areas.

I'd also turn off the SWG- mainly to save it but just using liquid chlorine to SLAM gives you an idea of how much FC you are losing. If your confident on your CYA reading stay the course and brush regularly, you should notice a reduction in the visible algae over time.
my problem is, i'm back at work now, and won't get home till around 18:00 when it will probably be too cold/dark to get in the pool and brush

so i've left the SWG on 100% to keep the FC up during the day and will test again tonight

FC was 32 this morning
 

Stooge007

Active member
Jan 10, 2017
28
Sydney, Australia
FC was 36 when i got home from work

was a bit cold to get in the pool, so brushed as best i could from where i could remember the spots were

dropped SWG to 80%

will try and come home from work early tomorrow, to give it a brush from inside the pool, then will do an OCLT

the water is the clearest i've ever seen it at the moment!

hopefully algae is dead by tomorrow
 

Caco

Well-known member
Hey Stooge
Next time you brush, i would brush the whole pool. Sometimes you cant see the algae on the sides in its early stages
When I did my last slam I also wiped the skimmer and jets with a cloth, just in case, cos I couldnt see anything on them. But I ended up with a slightly green tinted cloth after I finished...
 

Stooge007

Active member
Jan 10, 2017
28
Sydney, Australia
Hey Stooge
Next time you brush, i would brush the whole pool. Sometimes you cant see the algae on the sides in its early stages
When I did my last slam I also wiped the skimmer and jets with a cloth, just in case, cos I couldnt see anything on them. But I ended up with a slightly green tinted cloth after I finished...
i brushed the whole pool on the weekend

will hopefully have time to brush all over again tonight

hoping everything is dead by now, this will be Day 4 of FC > 28
 

Stooge007

Active member
Jan 10, 2017
28
Sydney, Australia
got in the pool and pressure washed all the algae i could see

there were still some very minor green patches

for the most part, was pretty algae free

FC sitting at 37, will drop SWG right down

pretty sure i'd pass an OCLT at this point, but will keep the SLAM going another day

much longer process than i'd thought!
 

Jezza

LifeTime Supporter
TFP Guide
Jan 18, 2015
969
Bunbury, WA, Australia
Yep good plan if you can still see algae you unfortunately need to keep going. How are your reagents going- you don't want to have come this far to run out.
 

pabeader

LifeTime Supporter
TFP Guide
May 14, 2015
4,349
Cartersville Ga
Just to make the point very clear. If you see any algae anywhere in or on your pool; you aren't done yet. If you were to stop now, the chances are very good that you would just need to start all over again.
 

Stooge007

Active member
Jan 10, 2017
28
Sydney, Australia
turned SWG off, FC had drifted down to 27

i thought i may as well keep things going, but probly won't be home tomorrow to test etc.

so added another 1L of chlorine to raise FC by 5, just in case i can't make it home tomorrow night

will maybe have to wait till Saturday (2 days away) do do an OCLT, but pretty confident everything will be dead by then
 

Jezza

LifeTime Supporter
TFP Guide
Jan 18, 2015
969
Bunbury, WA, Australia
Well done in keeping it up. Have you looked to see if there is any more algae. Also wondering if you can do a quick test and redose before heading off tomorrow?
 

Stooge007

Active member
Jan 10, 2017
28
Sydney, Australia
Well done in keeping it up. Have you looked to see if there is any more algae. Also wondering if you can do a quick test and redose before heading off tomorrow?
haven't been in the pool yet, we've had torrential rain in Sydney the past couple of days

had to pump put some water last night, otherwise pool was going to overflow

FC was 27 this morning, but i would've lost some CYA in the pumping out of water, will need to test that when the sun comes out

going to be cold and rainy all weekend, so may as well keep FC @ shock today, then OCLT tonight and then let FC drift from tomorrow (Sunday)
 

Jezza

LifeTime Supporter
TFP Guide
Jan 18, 2015
969
Bunbury, WA, Australia
The cold weather should help you out for sure. It'll be interesting to see how your OCLT goes tonight.

(We on the other side are expecting 36 degrees over the weekend.:swim:)
 

Stooge007

Active member
Jan 10, 2017
28
Sydney, Australia
forgot to update

passed OCLT on Sat night, FC drop of ~ 1 (29 -> 28), CC of 0, water clear as

so now going to let FC drift down, but will re-check CYA when it's sunny again (given i pumped out a bunch of water when it was storming last week)

cheers all
 

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