How do you know when you're done Slamming?

[DLB1641]

On the 18th we noticed that our water just had a tinge of cloudiness....we tested everything and all results were fine. We waited another day and it was slightly more cloudy, and when I brushed the bottom of the pool, there were mild green plums. I decided we needed to slam, based on info here, we had algae.

It took a lot of bleach and 7 days...we tested at least twice a day, and added accordingly to keep up to SLAM level. We vacuumed the little brown patches ( which I am assuming were dead algae, and swept and more vacuuming daily...) you get the picture. Finally, day 7 the water cleared, it looked great. Still brushing and vacuuming daily, and testing....there were very few mild green puffs when I would brush the bottom, so according to the directions, with the ppm, not dropping like it did at first, we let the chlorine level drop to normal. We thought we were done....that was 5 days ago. The water still look clear...but there is still little puffs of color when I brush the bottom....I kept thinking it was just dead algae....

I guess my question is.....'how do you know when you are officially done Slamming?' We decided to take it back up to slam level yesterday, that maybe we didn't get it all.?
This is the first time we have had an issue all summer. We religiously test, sometimes twice a day....I was disappointed that we even had this happen, but I look at it as a learning experience.

Are the 'puffs' when I hit spots on the bottom, DEAD algae, or LIVE algae....how do we know when we are done. This is so frustrating.

Thank you for all of your input. We would like to be able to swim maybe for the last weekend this summer....

 

[Mr Bruce]

It's in the SLAM article:
You are done when:

CC is 0.5 or lower;
You pass an OCLT (ie overnight FC loss test shows a loss of 1.0 ppm or less);
And the water is clear.

Pool School - SLAM - Shock Level And Maintain

 

[DLB1641]

CC has always been .5 and is at 0. Water is clear. We did pass the 1.0ppm last week, so I thought we were done.

So does that mean the light puffs of 'algae' I am seeing are dead algae, or live?? That is what has me confused.

 

[Mr Bruce]

Probably dead.

"Clear" is crystal clear. Quarter on the bottom is heads or tails no questions, even after a good brushing.

If all that passed, you might want to verify your CYA. I hope you aren't using those strips in your sig for anything

 

[DLB1641]

I use the TF-100, the water is crystal clear, except when I see the tiny brown spots and vacuum them then brush....still light plums..that is what is making me wonder if we still have some left. CYA 45

 

[Mr Bruce]

It's possibly not algae then. I have this one spot where a tree drops something in the pool that could easily be mistaken for dead algae but I know it isn't. It's always in the same place (clue #1) and my chlorine demand is very consistent (clue #2). Another test that algae is taking hold is slick walls, but that should show up in an OCLT.

 

[DLB1641]

Okay.....my husband requested that I ask another question regarding this SLAM.

Last night 4pm: 19.0ppm added 1.5gal bleach
Last night 7pm: 25.0ppm
This morning 7am: 20ppm added .5 gal bleach
Same day 7pm: 16ppm

The weather has not been hot, we have had some rain off and on. Our pool is crystal clear ( I can count the eyelashes on an Abe Lincoln penny, its so clear) now and very little to vacuum. The ONCL is more than 1ppm, so does this mean we keep it at SLAM level? This has been going on two weeks now.

We have some leaves dropping that are going into the skimmer, we clean it one to two times a day......would this be why it's using so much? I guess we don't know when to let the chlorine drop back to normal. I am thinking we are going to have to close it this weekend or next anyway, so is this all for nothing?

Should we add another gallon tonight?

 

[jblizzle]

So you lost 5ppm overnight, that would be a failed OCLT (assuming there was no sun on the pool between 7 and 7.

Don't add more FC, just do another OCLT test tonight and see what happens.

With your season coming to and end, I might just let the FC drop and enjoy the pool for a could more weeks and then close it following the article in Pool School ... which BTW says you should NOT close the pool until the water is < 60 degrees

 

[DLB1641]

Even though we are no longer at the correct Slam level?

 

[jblizzle]

Given the time you have been at it and the stated clarity, maybe the OCLT had testing error

 

[MarianParoo]

Yes, you don't have to be at slam level to do an OCLT.

 

[DLB1641]

Well, last night, it went from 16ppm to 17ppm. That is strange, but at least it didn't drop! So I guess we are done with the SLAM.

One last question for all of you knowledgeable people....should the chlorine level stay fairly level with a little bit of loss each day? Ours would go from 6ppm to 1ppm, over night, everyday, not with heavy bather loads. It was using a lot all summer, everyday...or is that a sign something is in the water it is trying to take care of? We were adding a 1/2 gal or more everyday. If this sounds normal, thats fine. I hate that it drops that low to 1ppm. How do we keep it closer to 6ppm more regularly? Maybe that is why we got the algae start, because it was dropping so low. Our CYA was always around 45.

Since we are new pool owners- new to the BBB method, we are trying to get a idea of what is 'normal' at least for our pool so we have something to gage things by.

Thanks again for all of the great advice from everyone.

 

[Mr Bruce]

2-4 FC loss per day is "standard". With a CYA of 50 (round up) that means it should never fall below 4. That means you have to add whatever it takes every day to keep it above 4.

5ppm loss overnight means there is something consuming chlorine that isn't UV and a SLAM is in order. 5ppm loss on a hot summer day is on the high end but not necessarily a sign that a SLAM should happen.

 

[DLB1641]

Thank you for the info!

 

[clpett]

We're in a pretty similar place and I'm at a loss for what to do next.

We've had an unusual amount of rain over the past two weeks. We've also had a cedar elm drop a heavy load of seeds into the pool over the past two weeks. The seeds were enough to clog our 100 sq ft DE filter (intentionally oversized on a 15k gallon pool). That caused the water to get cloudy. It looks like the rain and seeds have finally stopped. Here's what we've done:

1) backwashed the DE filter the past two weekends
2) SLAM the pool for the past 6 days

I measured the CYA to be at 30 PPM so I was slamming to 12 PPM FC for the first few days. Since that didn't have an effect, I bumped the SLAM level to 16-18 PPM FC thinking that my CYA reading might be inaccurate. Our pool has eaten through ~100 ppm of FC over the past 6 days with no slow down in site. All the while, the pool looks absolutely crystal clear. We've been cleaning out the vacuum bag, the skimmers, and the filter basket multiple times a day. We've been brushing once a day but there is nothing really to brush. There is still some tree debris but it doesn't seem like it should be eating that much FC. My only thought is that something is hiding in the filter but I would think it should be dead by now.

Our OFCL test from this morning showed a 3 PPM loss and 0.5 CC. I plan to backwash again tomorrow. We made it the entire summer without needing a SLAM. Up until this point, our daily FC loss was 3 PPM. However, this episode has me losing confidence in my ability to understand and care for the pool.

Thoughts? Suggestions?

[adding thoughts]

Is there any way to tell if I'm wasting a bunch of effort and money trying to eat up the tree debris rather than some real algae/microbe problem. If it is tree debris, should I just stop the SLAM process? Or should I always assume there is something nasty and SLAM until resolved?

 

[DLB1641]

Your situation sounds just like ours. We have a mimosa tree and a black walnut. They are both giving us a run for our money. We emptied our skimmer baskets/ back washed/brushed/vacuumed everyday too. We have had crystal clear water too, but blowing thru bleach at a crazy rate. Last night we finally didn't get a loss. This whole process has taken over two weeks. I didn't understand how it could look so clear but still be using that much chlorine. We bumped our slam up to over 20, and finally after 2 weeks....we had no loss last night. We felt the same way and thought this was never going to end, that we were doing something wrong. I have read everything on the site and others and searched everything that has to do with cloudiness and slamming. Maybe two weeks is normal for a slam, not sure since this is our first. Sure seemed like a long time to us. We lost the last two weeks of the swimming season now the temps are cooling down.

- - - Updated - - -

Yes, you don't have to be at slam level to do an OCLT.

I didn't know that....but that makes sense!

 

[MarianParoo]

Sorry that it took so long. That happens. How often were you able to keep your FC at or slightly above slam/shock level?