Looks Like Im Going To Have To Slam

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RodRamos

RodRamos

In The Industry
Jul 24, 2019
144
Trinity, Florida
Like the title says, looks like I'm going to have to SLAM for the first time. Last Monday I worked 12 hours and was running late so I didnt get to test/dose with chlorine. I asked my wife to do it but she didnt get to it until 6:45pm. I also noticed FC levels were dropping faster than usual the past week or so.
The water has been crystal clear and CC has been under .5 but yesterday I noticed some green (very little and very faint) at the bottom of the pool and I knew it.
Did the OCLT last night. Tested after dark at 8:30pm and FC was 4.0. Then tested again this morning before sun up and it tested 2.2 with a loss of 1.8ppm.
My pool is small (12×30 and 1730 gallons) so changes typically happen fast and I dont want this thing to go full bloom before I can fix it. We have had a lot of rain lately and the pool is under an oak tree (which I plan on removing) so I constantly empty the skimmer basket and have to manually skim as well.
This is the first time SLAMing so I'll have to read up and get a good grasp on it before I attempt it.
 
Rats!

Next time you end up not being able to add chlorine or don't get to it till the next day, just add a couple/few ppm above target. Or, better yet add 1-2ppm above target every day just in case you have a long day again.

Doing OCLT at or under minimum probably didn't help much either.

You could drain and refill, but I get the feeling you are fine with having a SLAM under your belt.
 
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frogabog said:
Rats!

Next time you end up not being able to add chlorine or don't get to it till the next day, just add a couple/few ppm above target. Or, better yet add 1-2ppm above target every day just in case you have a long day again.

Doing OCLT at or under minimum probably didn't help much either.

You could drain and refill, but I get the feeling you are fine with having a SLAM under your belt.
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I really cringe at the thought of draining and refilling. I have doing it. I haven't done a SLAM either so I may hate doing that more then draining/refilling who knows.
I'll pick up a few extra jugs of chlorine today.
I hate the thought of wasting so much reagent but oh well.

Heres a picture of the water this morning. The green is worst than yesterday (please excuse the wrinkles, we knew we only wanted the pool for one season until we upgrade so I didnt pay as much attention to smoothing them out.)
20190911_081734.jpg
 
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That's clearly algae. OCLT was unnecessary with visual algae like that ;).

Take account of the pump running 24/7, SLAM level chlorine, and reagents... then compare to draining, washing with bleach, refilling and adding a bit of CYA. Hard to judge how much chlorine it'll take since you don't know how long your SLAM will take (a few days likely, minimum), but I feel like with that little bit of water the cost is likely less than SLAM. Your choice. You could probably get the wrinkles out while you're at it too.
 
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frogabog said:
That's clearly algae. OCLT was unnecessary with visual algae like that ;)
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I know right? Yesterday when I visually inspected the pool it wasnt anywhere near that bad. Sure there was some in there, but I almost wish I had a picture just to show the progression from one day to the other. I was kind of shocked to be honest when I saw it this morning.

frogabog said:
Take account of the pump running 24/7, SLAM level chlorine, and reagents... then compare to draining, washing with bleach, refilling and adding a bit of CYA. Hard to judge how much chlorine it'll take since you don't know how long your SLAM will take (a few days likely, minimum), but I feel like with that little bit of water the cost is likely less than SLAM. Your choice. You could probably get the wrinkles out while you're at it too.
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To be 100% honest here, earlier this morning I started to hookup the discharge hose and run it to the street to drain it. It's the most practical, simplest and cost effective option. But the more I thought about it, I thought it would be nice to get through a SLAM process to kind of learn what to expect, so that next season, when we have a 7000 gallon pool, and I come across this situation, I'll be more comfortable doing a SLAM and will know what to expect.

frogabog said:
...I get the feeling you are fine with having a SLAM under your belt.
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You kind of read me like a book there roffl.???
 
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Ok so I got the pH to 7.2, skimmed, brushed the bottom and walls really good and vacuumed. Poolmath tells me my SLAM FC is 16. Dosed the water with the recomended amount of chlorine. Going to retest in 30 minutes to see where the FC is. Then will retest again tomorrow morning. I have the next 4 days off so I will keep a close watch on the pool chemistry. Pool School recommends testing at least twice a day but no more then once per hour so I'll try and test every 3 hours or so and adjust as needed.
 
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Are you using 25ml for testing FC? Try 10ml and then each drop is .5ppm. It'll save reagents.

Did I already mention that? Feels like I did. But maybe not. Every time I see .2 in results I try to save people some money so I tend to say it a lot here lately. Taylor instructions show the 25ml option first so people tend to go with that off the bat.
 
The first test I did 25ml, subsequent tests I did 10ml. So far so good. FC has been steady at 16ppm or above but not by much, I'm keeping a close eye on it so it doesn't drop below 16ppm. I was going to do the first OCLT tonight but I feel like I should wait at least 72 hours of SLAM before checking.
 

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duraleigh said:
Good Plan!

You have an excellent grasp of the process........your SLAM will go well and you pool will be crystal clear.
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Thank you, I decided to give it one more day before doing the OCLT. Tonight marks the 4th day of SLAM. The water is crystal clear and there is no visual signs of algea. Tonight I will dose the pool one more time to keep it above FC SLAM level and tomorrow in the morning I will do the OCLT and CC test.

If chlorine loss is less then 1ppm and CC is less then .5ppm I will stop the SLAM process and let chlorine levels drop to normal levels and I'll do a full set of tests just to make sure everything is where it's supposed to be.

Once it's all back to normal were going for a swim. Cant wait. It's been hot lol.
 
Tonight I will dose the pool one more time to keep it above FC SLAM level and tomorrow in the morning I will do the OCLT and CC test.
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That's a little bit unclear. The OCLT test begins in the evening with SWG off and NO further chlorine additions. It is ended the next morning (before the sun hits the pool) I think you know that but that is not what you are saying.

Secondly, why do you feel the need to increase FC OVER SLAM value?
 
duraleigh said:
That's a little bit unclear. The OCLT test begins in the evening with SWG off and NO further chlorine additions. It is ended the next morning (before the sun hits the pool) I think you know that but that is not what you are saying.

Secondly, why do you feel the need to increase FC OVER SLAM value?
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Sorry, I meant to say today I will dose one more time (which I already did), not tonight, i want to make sure i dont drop below my SLAM value in the afternoon (which shouldn't happen IF the algea is gone) I just want to make sure.
I'll begin the OCLT this evening by testing for FC after sundown, but will test for any loss of chlorine tomorrow morning before the sun is up. I'm hoping for less then 1ppm loss and CC of .5 or less. The water is already crystal clear and there's no sign of green algea at the bottom or walls which is good. I've been skimming, brushing and vacuuming diligently.
I tried to keep FC 2 or 3 ppm above SLAM value because I read you should never let it drop below SLAM value and when I first started the SLAM process I got it to 16, which was my SLAM value but 2 hours later when I tested it was at 14ppm. I figured I should probably keep it 2 or 3 ppm above in case it drops. It shouldn't anymore, but I want to be sure. Let me know if I need to make any adjustments to my process. I want to make sure I have the process correct.
Rod
 
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