First SLAM -- need some hand-holding

heat4212

Active member
Jun 13, 2021
36
Lafayette, IN
Pool Size
21900
Surface
Vinyl
Chlorine
Liquid Chlorine
I just want to say thanks for giving your time to help us newbies fix our problems! And also thanks for offering PoolMath at such a reasonable rate. I got signed up this morning.

I would like to begin my first SLAM asap but am nervous and have some questions.

But first here's our most current test results:
(Note: we drained 2 feet of water last night and refilled and didn't add more chlorine before testing)

9:30 am
--FC 0 CC 1
--CYA 45 (down from 120 from draining and refilling)
--Alkalinity 230 -> added 4 gallons Muriatic Acid and retested at 3:30 pm and it was down to 130
--pH 7.0 (fell after adding acid but is back up after aerating all day with fountains and shop vac)
--CH 450

Here's my SLAM concerns:
--Can we start the SLAM with a pH of 7.0 instead of 7.2? I've been fighting high Alkalinity and low pH since we started paying attention ourselves and I don't want to add anything to raise pH until after SLAM if I can help it.
--Can we start now (it's 82 and mostly sunny) or wait until sunset?
--Is it better to leave our heater off until after the SLAM? It's been pretty warm here so the water has been in the low to mid 80s but the water temp is colder now due to partial drain/refill.
--Can I get in the pool to brush the sides during SLAM? I have read on the forums that you can swim during SLAM if FC is below shock level. But this confuses me a bit because I thought we were supposed to check every hour or as much as practical and bring the FC back up to shock level whenever it falls below. Are people who are swimming during SLAM just taking the process a little slower? I plan on dumping chlorine in every 2 hours if need be! Do I just jump in and brush really quick when FC falls but before I bring it back up?
--Can I pour in Chlorine while my robot is running or should I pull him out?

Again thanks everyone. And happy early Father's Day!
 
- pH of 7.0 is fine to start.
- No need to wait. SLAM away.
- I wouldn't bother with the heater during the SLAM. Save the energy. It wouldn't hurt or help anything really.
- You can safety swim in water that is above minimum FC, at or below SLAM level, and you can see the bottom of the pool. You can brush the sides from in the pool, but most people brush from the pool deck - don't think you'd want to be in it. You're only bringing the FC up to SLAM levels, not beyond it, so it's safe from that perspective anyway.
- Robot should be fine at SLAM levels. Add chlorine slowly at a return jet to help it disperse out into the pool.
 
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That drop in CYA is more than one would expect with a 2 foot drain and refill. Was the pool well mixed before taking your sample?
pH of 7 is fine.
Time is of the essence. Start.
I would leave the heater off until the pool is clear enough to swim in.
The water is safe to swim in if AT or below SLAM level FC. Just be sure you can see the bottom or have a standby person out of the pool for safety.
You can add chlorine while the robot is in the pool. Just be sure to add chlorine in a pencil size stream at a return with the pump running.
 
That drop in CYA is more than one would expect with a 2 foot drain and refill. Was the pool well mixed before taking your sample?
pH of 7 is fine.
Time is of the essence. Start.
I would leave the heater off until the pool is clear enough to swim in.
The water is safe to swim in if AT or below SLAM level FC. Just be sure you can see the bottom or have a standby person out of the pool for safety.
You can add chlorine while the robot is in the pool. Just be sure to add chlorine in a pencil size stream at a return with the pump running.
That's a good question about CYA. We had not started the pump again when I took the sample so I'll take another. I will be very sad if it's a lot higher!

And thanks for the tip about adding chlorine.

I forgot to hit post, but we're home now and we re-measured and it's now 33-37 ish (depending on if you trust me or my husband's interpretation more). All I can figure is that the way our pool is built it's 3 ft deep and all-around with a 5 ft deep part in the middle. And it was already low when we drained so 25" out and 28"
in means we replaced more than 1/2 of the volume according to the calculators.

So we added 3 gallons of chlorine and the pool instantly turned green!
 
If CYA is between 30 and 40 you can just call it 40. It's not a linear test, so you can't extrapolate between the lines.

Going green as you add chlorine typically means metals in the water that are falling out of solution as the chlorine is added. Did you fill from a well? Do you have any iron stains around your fixtures in your house if you do get water from a well?
 
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PXL_20210619_203630086.jpgPXL_20210619_233900623.jpg
Blue is before starting SLAM, green is after. I'm not freaking out though because this happened to our little Coleman hot tub the night before last after draining and refilling (but way worse). I rinsed the filter every hour for a day and it was crystal clear after 24 hours. I'm kind of glad the the iron precipitates out! (If that's the right terminology). We don't even have well water!
 
If CYA is between 30 and 40 you can just call it 40. It's not a linear test, so you can't extrapolate between the lines.

Going green as you add chlorine typically means metals in the water that are falling out of solution as the chlorine is added. Did you fill from a well? Do you have any iron stains around your fixtures in your house if you do get water from a well?
We don't have a well but I believe the city of Lafayette, IN gets it's municipal water from wells and they allow metals to be at .3 (according to their water quality reports if that's even relevant). We use softened water in the house but our hoses don't go through the softener. Weird it didn't do that a week ago though after partial drain/refill. Maybe they need to flush?
 

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So some good news I think... Here are my last 3 test results. CYA is 40 so SLAM level is 16

11pm FC/CC was 11/1 added LC to 16
6am 11/1 again added LC to 16
8am 16/1 so no LC added (right?)

That seems like a good sign for the first time ever the pool is hanging onto to FC. But it's still atrocious looking. Which got me thinking, our iron filled hot tub was still clear though green/brown. This pool has been cloudy since Memorial day. Plus the filter pressure has never risen above 12 (10 is normal) and backwashes take 2 minutes. So we are going to leave the filter off for a bit and attempt a deep clean. I would rather not towards the beginning of a SLAM but since no chlorine is needed at the moment I am hoping it will be okay. Plus it seems the SLAM won't be that effective if the filter isn't working optimally. We moved into this house in December so I have no idea the maintenance history on it but the pool was put in about 5 years ago.

Since it's father's day so I hope you are all taking the day off but posting makes me feel better! Hope you don't mind.

PXL_20210620_122730967.jpg
 
Deep cleaning the filter will not hurt. The FC consumption will slow down. Do be sure you brush / vac the pool at least once a day. It is important to get the algae mixed up and disrupted so it gets attacked by the chlorine.
 
I actually have a bag of polyfill. Should I put it in a pillowcase or something?
I haven’t done it before but I believe it goes right in the skimmer to catch the iron. Might be worth finishing the SLAM first so you don’t get it gunked up with algae first maybe?
 
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Man, that was one clean looking filter. The sand looked Michigan dunes pristine. Nothing caked on top or anything. But I cleaned it best I could anyway.

I couldn't get the filter out of the pool house so I put one hose in to siphon and one to spray and stirred the sand with a broom handle. (I couldn't shove the hose down far enough... The opening was rather small and the filter is very tall.) I did that for about an hour even though the water never looked that dirty and then let about a gallon splooge over the top just to make sure anything floating got out. I backwashed and rinsed and the jets do seem stronger at least.

Speaking of, I covered the returns with socks and stuffed a pillowcase full of polyfill in the skimmer and have been rinsing them when they get orange enough. I should be getting the biodiesel filter socks on Monday.

My husband and FIL say they can see a little further down than yesterday but I think they are just trying to make me feel better.

Is it going to be okay some day?!
 
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You'll get there. Just keep the FC up at SLAM level with testing many times a day and adding FC so you don't go backward. :) Then let the filter do its job.

If you want you could buy some DE and add that to the filter - see: Add DE to a Sand Filter - Trouble Free Pool - but it will require some babysitting. Still, it will catch gunk faster that way.

Note your clean pressure on your gauge and only backwash when it gets to 25% more than that pressure. Sand filters work better as they get more dirty, until water flow is impeded.
 
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You'll get there. Just keep the FC up at SLAM level with testing many times a day and adding FC so you don't go backward. :) Then let the filter do its job.

If you want you could buy some DE and add that to the filter - see: Add DE to a Sand Filter - Trouble Free Pool - but it will require some babysitting. Still, it will catch gunk faster that way.

Note your clean pressure on your gauge and only backwash when it gets to 25% more than that pressure. Sand filters work better as they get more dirty, until water flow is impeded.
I'm checking FC every two hours. Brushed the sides twice so far and have the vacuum running (hope the poor guy doesn't turn orange). It's nice adding 1-2 quarts LC at a time versus 3 gallons!

Thanks for the DE suggestion. Ace carries pool grade so I am going to run out and grab some.
 
Just follow the article closely - you have to add only a little at a time and check your pressure with each addition. Too much and you'll just clog it up and prevent it from even letting water through.
 
Just follow the article closely - you have to add only a little at a time and check your pressure with each addition. Too much and you'll just clog it up and prevent it from even letting water through.
Thanks!
We just added 2 cups following the instructions exactly. No change on water pressure but we are going to stop now and maybe add more tomorrow.
 
Since you're new to the house and pool, you really can't be sure what crazy strange potions the previous owner dumped into the water. Cheap algaecides usually contain copper, as does Clorox products called XtraBlue. Avoid these at all costs. Avoid Clorox pool products like salt also.

Take a picture daily at the same place (over the stairs is good) and post it so we can see changes.

That's great news about the polyfil working. Keep that up!@

Maddie :flower:
 
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