SLAM Process Confirmation

[Jmischel]

I’ve inherited the maintenance responsibilities for my father in-laws in-ground pool. I’ve been reading as much as I can on this forum as I’m very new to pool maintenance and water chemistry.

My readings according to the Taylor 2006 on Friday were:
FC .6
CC .8
pH 7.3
CYA 50

I’ve been dealing with very low free chlorine all summer. We’ve been adding 2-3 lbs of dichlor regularly (every 3-6 days) but it barely raises the FC. The water clarity is excellent, no hint of algae. The pool is currently very clean but had a lot of leaves in it when we opened it up this May. We were also without a robot for about 5 weeks after we opened up. Cleaning and maintenance is on a good schedule now, though.

From what I’ve read, I need to SLAM the pool to rid it of the combined chlorine. The calculations tell me that at CYA 50, I need to get to FC 20 to achieve break point. I bought 5.25% liquid bleach so I believe I need 11 gallons to get to FC 20.

My questions are:
1. Does SLAM sound like the necessary approach given those statistics?
2. Do my calculations of FC 20 and 11 gallons bleach sound accurate?
3. With no hint of algae, would you expect me to be able to hold the FC 20 fairly easily once its achieved?
4. Is it accurate that we can safely swim in the pool up to the break point?
5. Can I keep the pool covered after I add the bleach? Its raining today so it would be a good day to SLAM this if I can keep the pool covered.
6. Any other advice?

Thanks for the forum. Looks like a wealth of knowledge on here.

Have a great day.
Jason

 

[Texas Splash]

Hi Jason and welcome ! You have a lot of questions, so I'll get right to them:
1 - Yes, but not just because of the elevated CC. Given the very low FC level and consistent loss of FC, I would SLAM.
2 - Using PoolMath … yes
3 - Depends. Test fairly often at first as that's when it will drop the soonest. Once the SLAM has been maintained for a day or two you should see things settle quite a bit.
4 - Yes - up to an FC of 20.
5 - You can, but I would leave it open for a good time to allow sun (when available) to help oxidize the CCs.
6 - Just follow the SLAM Process page. Maintain the FC level, brush, vacuum as needed, etc. Good luck!

 

[#40Fan]

nevermind....

 

[Texas Splash]

How about just adding enough bleach to get your FC into normal ranges? Check daily and adjust FC with just bleach and check your CC after a few days.

The OP certainly has that choice. But given this statement:

I’ve been dealing with very low free chlorine all summer. We’ve been adding 2-3 lbs of dichlor regularly (every 3-6 days) but it barely raises the FC. The water clarity is excellent, no hint of algae.

The consistent loss of (and low) FC with an strong CYA of 50 is concerning. But still, if the OP chose to do an Overnight Chlorine Loss Test this evening before implementing a SLAM, that's fine too.

 

[Jmischel]

Update at 4:00 pm:
Before starting my SLAM process, I tested my water and need to update my original readings:
FC .6
CC .8
pH 7.4
CYA 30

Based on those readings in my 30,000 gallon pool, I added 7 gallons of 5.25% bleach at 2:00 pm to attempt to hit a FC of 12.

At 4:00 pm, I tested the water and received the following readings:
FC 1.0
CC 2.4
pH 7.4

Is it normal for the CC to rise like that? Is it surprising that all of the chlorine was consumed so quickly? Do I just keep hitting it with chlorine and testing every two hours until I hit and maintain that 12 number?

Thanks,
Jason

 

[SpringPool]

Yes the cc is high because whatever is in your pool is consuming the FC. Or you could say the FC is trying to get rid of the stuff in your water

Either way you need to get FC to 12. I would add more bleach and test in about 30 min increments at first if the first time you test you don’t hit 12 add more base on the number. Once you get to 12 test ever hour or so. As it becomes more stable longer intervals in testing. Also you can go over 12 just not to let t drop below 12.

To save on reagent at first you can use a 5ml sample of water and each drop is 1ppm. For the OCLT use a 10ml sample once you get to that point.