SLAM frustration

[Mark’s Pool]

Have struggled all summer with low FC and high CC. Installed SWG in June and it couldn’t get FC level up. Pool was mildly cloudy; a few minor spots of green algae. Decided to do SLAM.

New TF-Pro test kit. At start of SLAM:
FC .37
CC 1.0
TA 110
PH 7.3
CH 225
CYA 45

Working on SLAM since Saturday morning. Pool has been crystal clear for days with no visible signs of algae. OCLT the past 2 nights is a drop from my 18FC SLAM level to 13FC. CC fluctuates between .5 and 1.

Have added 43 gallons of 10% liquid chlorine and 5 bags of Dichlor granulated shock (ran out of liquid and couldn’t get to store) during the last 5 days. Going to go broke and the pool looks perfect!! I have scrubbed in the skimmer, in the shallow end rope nooks, in the built-in ladder step. I have Sealed LED lights so no pool light cavern.Where could the algae be hiding that I keep failing the OCLT?

Broke and ready to give up! Help!!

 

[duraleigh]

Stop the dichlor! It adds a surprising amount of CYA to your pool. I assume .37 FC is a typo and you meant something else.....please clarify.

It's important to remember the purpose of the OCLT. It takes FC loss because of UV light out of the equation so the ONLY thing that can possibly consume chlorine in your pool is organic. There is no mystery to that hard issue.......assuming you do the OCLT correctly, your FC is being consumed by organics (algae). BTW, it is not really hiding, it is dying hence the decrease in your chlorine.

The only way to kill the algae is with chlorine. Please don't buy Magic Potions from the pool store hoping your issue is something else because it isn't. Chlorine is the answer until you can pass OCLT. Then you can end the SLAM and enjoy your pool provided you continue to use the correct amount of chlorine to prevent reoccurrence.

 

[Texas Splash]

I would also add it could be helpful if you updated your signature with all of your pool and equipment info. If you've struggled all summer, it would seem to indicate you never really got rid of any algae when you opened this season. Do you have a pool light with a niche behind it? A main drain (check under cover)? Any of these areas can provide a safe haven for algae, so you should check to be sure. We would round-up your CYA to 50 which would require an FC SLAM level of 20.

 

[Mark’s Pool]

I would also add it could be helpful if you updated your signature with all of your pool and equipment info. If you've struggled all summer, it would seem to indicate you never really got rid of any algae when you opened this season. Do you have a pool light with a niche behind it? A main drain (check under cover)? Any of these areas can provide a safe haven for algae, so you should check to be sure. We would round-up your CYA to 50 which would require an FC SLAM level of 20.

No pool light with niche. I have two main drains; guess I will try and see how long I can hold my breath!!

Can I get a reliable CYA test during a SLAM? If so, I will retest that.

My pool gets sun the entire day (that is, when the sun actually shines in Michigan )!

 

[Donldson]

You added about 10 ppm of CYA to the pool with the dichlor, so easier to just assume your CYA level is 60 and continue the SLAM Process using that to calculate your FC target.

 

[Mark’s Pool]

Stop the dichlor! It adds a surprising amount of CYA to your pool. I assume .37 FC is a typo and you meant something else.....please clarify.

It's important to remember the purpose of the OCLT. It takes FC loss because of UV light out of the equation so the ONLY thing that can possibly consume chlorine in your pool is organic. There is no mystery to that hard issue.......assuming you do the OCLT correctly, your FC is being consumed by organics (algae). BTW, it is not really hiding, it is dying hence the decrease in your chlorine.

The only way to kill the algae is with chlorine. Please don't buy Magic Potions from the pool store hoping your issue is something else because it isn't. Chlorine is the answer until you can pass OCLT. Then you can end the SLAM and enjoy your pool provided you continue to use the correct amount of chlorine to prevent reoccurrence.

The .37 FC before starting my SLAM wasn’t a typo. Was running my SWG and adding a couple gallons of chlorine a day and still couldn’t raise the level of FC. Have phosphates of about 1400.

Won’t use any more dichlor!! . Just had a few bags left from last year and temporarily out of liquid.

I just can’t understand how I could still have something organic in the pool after all that chlorine!!

 

[Mdragger88]

.37 fc isn’t a possibility with the tfpro-
It either gives results in increments of .2 (using 25ml sample) or .5 ( using 10 ml sample)
As @Donldson stated u started with 45 cya - which gets rounded up to 50 (no inbetweens) then u added 10ppm more w/ the dichlor so now your cya is 60ppm —> SLAM Process fc is 24ppm.
If u are falling short of that you aren’t being as effective.
Continue on
You are done when:

CC is 0.5 or lower;
You pass an Overnight Chlorine Loss Test
AND
the water is clear.
(Crystal Clear w/no algae dead or alive)

*Check & scrub every nook & cranny where it may hide (light niches, drain covers, ladder handrails, skimmer throats/weirs, etc.)
*Run slam level water through all water features & lines for at least a couple hours a day during the SLAM Process.
*Brush & or vac daily (this breaks up biofilms that algae uses to protect itself from chlorine)
*Backwash/clean filter when pressure rises 25%over clean pressure.