To SLAM or not to SLAM?

[Hawknz]

Hi All,

My chlorine has dropped from 6.5 to 3 in the last 2 days, likely because of increased usage, the pool is what I would describe as "slightly cloudy" , definitely not green, can still easily see the bottom at the deep end, but I can tell its not as clear as it was a couple of days ago.

using poolmath I have added enough cal-hypo to raise it back upto 6, but should I still SLAM the pool or will this be enough?, I'm not sure on the threshold to SLAM

Full Test Results prior

FC - 3

CC - 0

PH - 7.6

CYA - 60

TA - 100

CH - 240

Thanks in advance

 

[MarianParoo]

Hmmmm. It depends. How is your CC?

With the difficulties of getting reagents in Australia, I think you might be able to take the FC level up to target for a day or two and see how it goes. If it were my pool, I would probably just take it to shock level for a night and see. You have a different situation. It seems we are stretching the TFP boundaries a little with our Aussie friends!

In the future, when expecting a high bather load, take the FC to above target a bit so that you don't drop too low.

 

[MarianParoo]

You are different that Rob in that you have a "slightly cloudy" pool, btw.

 

[tim5055]

The true test is the OCLT. Bring your FC up to 10 and test just after the sun is off the pool. Keep the SWG off and test again before,the sun is on the pool the next morning. Only two thing "consume" chlorine; organics or UV. With no UV from the sun at night you will see if organics are in the water. Any loss over 1.0ppm FC is a fail and it's time to SLAM.

 

[Hawknz]

Hmmmm. It depends. How is your CC?

With the difficulties of getting reagents in Australia, I think you might be able to take the FC level up to target for a day or two and see how it goes. If it were my pool, I would probably just take it to shock level for a night and see. You have a different situation. It seems we are stretching the TFP boundaries a little with our Aussie friends!

In the future, when expecting a high bather load, take the FC to above target a bit so that you don't drop too low.

Hi MarianParoo

Restested and FC is back up-to 7 (my target level for CYA) , CC currently between 0 & 0.5 , pool still looks marginally cloudy

It dropped from 6 - 3 in 2 days since my last test, because of high bather load today and yesterday and very hot weather I'm guessing, I would never have predicted a drop that quick otherwise I would have manually added some to compensate, have increased the SWG from 40-50%

Thanks for your help

 

[Hawknz]

The true test is the OCLT. Bring your FC up to 10 and test just after the sun is off the pool. Keep the SWG off and test again before,the sun is on the pool the next morning. Only two thing "consume" chlorine; organics or UV. With no UV from the sun at night you will see if organics are in the water. Any loss over 1.0ppm FC is a fail and it's time to SLAM.

Thanks Tim, good point, I will try that tonight

 

[MarianParoo]

I would also add that during hot, sunny weather, (and especially with any swimmers), you should test your pool daily for a while. Once you know your pool a bit better, you will get a feel for it. You are still new to self-testing so better cautious than sorry!

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Oh, yea. If you are going to try an OCLT, turn off your SWG and keep the pump going overnight.

 

[Hawknz]

I've heard before about the need to raise FC to 10 or 12 to preform the OCLT , also continuously running the pump. Should these 2 things not be added to the OCLT "How To" page in pool school?

 

[MarianParoo]

My suggestion to keep the pump on is my own, and from my experience. It won't hurt other than a few KWH...

As to the minimum FC required for an OCLT, that is debated a lot on TFP. Personally, I would do an OCLT at slam levels just to be sure, but that is me. We know the OCLT is questionable at low/high FC/CYA ratios.

 

[MarianParoo]

I meant the pool pump, btw. The SWG should definitely be off.

 

[Hawknz]

So I preformed the OCLT , FC dropped 1.0PPM so I have commenced a SLAM, also despite raising the pool FC yesterday, today the pool actually looks worse although the bottom is still visible. So SLAM in progress as we speak

 

[MarianParoo]

Sorry, Hawk. Another lesson learned, huh? Hopefully this will be a quick fix as you were only below FC minimum for less than two days.

When it's hot here (if I can remember that long ago, hahaha), I test before and after guests. Before, I bump up the FC a little above target, and after, at least to target. In the heat, things can go sour quickly.

Remember that the key to a slam is to maintain FC at or above shock level. Ask if you have any questions or just need encouragement!

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I have also tested mid-day with guests if there are a lot of swimmers. I do it when everyone's out and eating or something.

 

[tim5055]

So I preformed the OCLT , FC dropped 1.0PPM so I have commenced a SLAM, also despite raising the pool FC yesterday, today the pool actually looks worse although the bottom is still visible. So SLAM in progress as we speak

It happens to all of us. I went camping (I believe it's caravanning for those of you down under) for five days last spring and left my Stenner pump turned off. While the pool was still clear when we got back the chlorine demand began rising. An OCLT proved that something was growing in the water. four days of SLAM and about a dozen bottles of bleach and all was well again.