Preparing for my first SLAM

[rbwamsley]

Hi All,

I'm preparing to do my first SLAM starting Thursday night. I'm keeping my water balanced as best as I can until then. I'm waiting until then so I can give it the attention that is needed. Also, it is supposed to rain today and tomorrow, so I'm hoping that will drop my CYA to an acceptable level before I start (if not, I will be doing some draining and refilling on Wednesday night).

Based on what I have read so far, I hoping my SLAM will take very long. My water clarity is already great and my CC is at 0.5, so as long as these stay constant I will just need to meet one more criteria.

Reasons for SLAM'ing

• Algae is coming back every week to week and half.
• My chlorine loss is ridiculous (see pool logs)

Questions
1) I read that it is okay to swim while SLAM'ing the pool as long as your pH is in range and your chlorine is below shock level. However, I cannot find anywhere what shock level is or how to calculate it... Is it really okay to swim while slamming and where do I find my shock level?

2) How many gallons of liquid chlorine should I have on hand? I currently have 5 gallons, but was planning to pick up another 2.5 gal jug.

3) I have the Jandy Nicheless LED lights on my sun self/tanning ledge. Do I need to pull those out to clean behind them?

4) Any other tips/tricks for having a successful slam?

Thanks in advance,
Blake

 

[Bperry]

For #1, your SLAM level is the amount of free chlorine in the water. It’s safe to swim anywhere up to that level. That number is determined by how much CYA is in the water. Higher CYA means your FC (free chlorine) needs to be higher.

I’d suggest posting what your water measurements are so you can get specific advice for the other questions. If you are trying to lower the CYA, the only way to do so it draining and refilling some amount. You can try draining out some water and letting the rain fill it back up but that’s only going to give you an inch or two.

“Shock level” isn’t a term that TFP uses.

Edit: for some reason your pool logs weren’t showing up but the link to then does work. A couple bits of advice:

1. Which test kit are you using? A CYA measurement of anything other than 10, 20, 30, etc doesn’t come from a Taylor test kit. If you are trying to interpolate between lines, don’t do that as it doesn’t work that way.

2. You need to follow the FC/CYA chart to determine how much chlorine to add and realize that an average pool consumes 2-4ppm per day. That means you need to add it every day to keep the level above the minimum shown on the FC/CYA chart. You had none a week or so ago so that may be why you are seeing algae.

3. I don’t think you are using more than average chlorine amounts, it just seems like it because you aren’t adding it every day and are having to catch up after it’s consumed. If you can test and add every day for a week or so and get it to stabilize, then you know about how much the pool eats every day. Then you can goose it up a bit and skip a day or two if needed.

 

[Newdude]

Also, it is supposed to rain today and tomorrow, so I'm hoping that will drop my CYA to an acceptable level before I start

One inch of rain will lower it by 1/average depth of pool in inches. 1/60th (?) Not much at all.

read that it is okay to swim while SLAM'ing the pool as long as your pH is in range and your chlorine is below shock level. However, I cannot find anywhere what shock level is or how to calculate it... Is it really okay to swim while slamming and where do I find my shock level?

You need to see bottom for swimmer safety. If someone went under, you need to know NOW and where.

If clear enough, FC up to SLAM (40% of CYA) is safe for people and equipment. See FC/CYA Levels

How many gallons of liquid chlorine should I have on hand? I currently have 5 gallons, but was planning to pick up another 2.5 gal jug

No 2 slams are the same. You don't want 15 gallons left over if it's an easy one. Many people have needed 15-20 gallons just for an idea.

have the Jandy Nicheless LED lights on my sun self/tanning ledge. Do I need to pull those out to clean behind them?

I don't believe so as there is nowhere (the niche) for bad water to collect.

Any other tips/tricks for having a successful slam?

Brush/vac a couple times a day.

Go on a full algae hunt. Every last inch is suspect until it isn't. Ladder rails, water features, auto fills, all up in the skimmers, the foam piece on the back of the skimmer door...... go buck wild looking. Every inch is suspect until it is cleaned or verified to be clean.

Awesome job starting when you have the time. You are only saving yourself. The more effort you put in, the better it goes. No matter how bad it is, it would be worse. 2-3 hour testing/adding makes a HUGE difference.

We got you. Keep us posted

 

[rbwamsley]

For #1, your SLAM level is the amount of free chlorine in the water. It’s safe to swim anywhere up to that level. That number is determined by how much CYA is in the water. Higher CYA means your FC (free chlorine) needs to be higher.

I’d suggest posting what your water measurements are so you can get specific advice for the other questions. If you are trying to lower the CYA, the only way to do so it draining and refilling some amount. You can try draining out some water and letting the rain fill it back up but that’s only going to give you an inch or two.

“Shock level” isn’t a term that TFP uses.

You can find my water measurements in the pool log link my signature. You underestimate Houston's rain. I've had it drop my CYA by 25 over 2 days, granted those were heavy rains. That being said, based on forecasts I will most likely have to do some draining and refilling before Thursday.

Here is the post that mentions "shock level". Granted it is 7 years old... Swimming during a SLAM

 

[rbwamsley]

Go on a full algae hunt. Every last inch is suspect until it isn't. Ladder rails, water features, auto fills, all up in the skimmers, the foam piece on the back of the skimmer door...... go buck wild looking. Every inch is suspect until it is cleaned or verified to be clean.

Thanks for this! I would have completely forgotten about my auto-fill.

 

[Bperry]

You can find my water measurements in the pool log link my signature. You underestimate Houston's rain. I've had it drop my CYA by 25 over 2 days, granted those were heavy rains. That being said, based on forecasts I will most likely have to do some draining and refilling before Thursday.

Here is the post that mentions "shock level". Granted it is 7 years old... Swimming during a SLAM

I edited my reply above. Something weird going on with the pool log link. I suspect shock level just means SLAM level in that post. The term is also used in the pool industry to mean something different so the normal term around here is SLAM level.

 

[Bperry]

You underestimate Houston's rain. I've had it drop my CYA by 25 over 2 days, granted those were heavy rains.

Ha, I think we’re getting some of that today over here. If you can lower the level in advance of a big rain, that will do better at lowering the CYA since you won’t have mixing of rainwater and pool water draining out of an auto drain (assuming you have one). My pool doesn’t have auto anything so I gotta go get a hose to fill or drain.

 

[rbwamsley]

1. Which test kit are you using? A CYA measurement of anything other than 10, 20, 30, etc doesn’t come from a Taylor test kit. If you are trying to interpolate between lines, don’t do that as it doesn’t work that way.

2. You need to follow the FC/CYA chart to determine how much chlorine to add and realize that an average pool consumes 2-4ppm per day. That means you need to add it every day to keep the level above the minimum shown on the FC/CYA chart. You had none a week or so ago so that may be why you are seeing algae.

3. I don’t think you are using more than average chlorine amounts, it just seems like it because you aren’t adding it every day and are having to catch up after it’s consumed. If you can test and add every day for a week or so and get it to stabilize, then you know about how much the pool eats every day. Then you can goose it up a bit and skip a day or two if needed.

1. TF-Pro kit. All my CYA's I have logged are above 55. Edit: I just went and read more about the CYA test, I see what you are saying now. I wasn't rounding to the next line like it says. I have also been doing the test at dusk or in my kitchen. That is probably making a big difference too. Will retest.

2 & 3) Are you suggesting that I may not need to do a SLAM and that I should wait to get a weeks worth of consistent data?

 

[Newdude]

I suspect shock level just means SLAM level in that post

It does. They rebranded it ages ago to stop newb confusion. Shock Level and Maintain. Maintain being equally critical in the process.

I would have completely forgotten about my auto-fill.

I am not there to go over your setup with a fine tooth comb so I hope to lucky guess ideas for you. But every last inch is suspect. You can fix the pool water and some is hiding in pain sight only to add new old algae next week.

You underestimate Houston's rain. I've had it drop my CYA by 25 over 2 days, granted those were heavy rains

Math is math. 2 inches of 0 CYA is 2/60ths drop in X CYA. (Or whatever your average inches are). If you have an overflow it's even less as some goes right out the pipe.

But everything else the pool store told you was a crock too. They weren't right when they told you is was 100, nor when they said it was 75 two days later. Then they pulled an excuse out of their rears to explain it.

Like I said, we got you now.

Are you suggesting that I don't need to do a SLAM and that I should wait to get a weeks worth of consistent data?

Your visible algae may be pollen, but from your intro thread it sounds like algae. None of us ever know, we Overnight Chlorine Loss Test. Take the UV/sun loss out of the equation. If you lose FC with no sun, it's algae.

Now that you have reliable testing, let's use it and find out.

 

[rbwamsley]

Your visible algae may be pollen, but from your intro thread it sounds like algae. None of us ever know. We Overnight Chlorine Loss Test. Take the UV loss out of the equation. If you lose FC with no sun, it's algae.

Now that you have reliable testing, let's use it and find out.

I will do the OCLT tonight or tomorrow. Would love to not have to SLAM the pool. Thanks

 

[Newdude]

Also, Bperry alluded to it above. You can't see in between the 10s on the CYA tube like it appears. Its logrythmic in scale and not linear. So always round up to the next 10. At that point, save the trouble and only fill the tube to the 10s. There is no need to try to decipher 44 or 47 when its wrong and both will be 50 anyway.

 

[Bperry]

Also, Bperry alluded to it above. You can't see in between the 10s on the CYA tube like it appears. Its logrythmic in scale and not linear. So always round up to the next 10. At that point, save the trouble and only fill the tube to the 10s. There is no need to try to decipher 44 or 47 when its wrong and both will be 50 anyway.

Yes, I’ve found doing the CYA test this way is so much easier. Just fill the tube up the first line and check for the dot. If you can see it, fill it up to the next line and check again. Once you don’t see it, you’re done. The tolerance on the test is something like +/- 10ppm anyway so 47 or 49 doesn’t matter.

 

[rbwamsley]

Well I did the OCLT and was surprised by my results.

Apr 12 - 7:58pm - FC = 4.5 ppm
Apr 13 - 5:41am - FC = 4.0 ppm

Taking those results and and looking at the Overnight Chlorine Loss Test doc I'm with in range of normal loss. That along with the fact that my algae hasn't come back yet, it looks like I may not need to SLAM my pool. Thoughts?

 

[Newdude]

Thoughts?

Pollen or fine dirt look and poof like algae. They don't eat FC, so overnight you lost next to none. .5 can be user error or Taylor error.
So the sun is eating your FC. We look next to CYA and yours is all over the place. Try to get a solid reading. Resuse the solution and get 2 or 3 tests in a row that agree. Only fill to the 10s. Use a quick snap of a glance or else the eyes see the dot no matter what.

We will likely raise the CYA to buffer the FC against the TX sun, but don't want to overshoot either, so we need good data.

Pay close mind to your FC in the meantime. Just like any other time of year, if it's been losing 6 ppm lately, expect it to continue and add at least that much a day, confirmed by testing before, and after.

 

[rbwamsley]

Pollen or fine dirt look and poof like algae. They don't eat FC, so overnight you lost next to none. .5 can be user error or Taylor error.
So the sun is eating your FC.

The thing that gets me about this is that the dirt/algae was only on the shaded areas of the pool.

We look next to CYA and yours is all over the place. Try to get a solid reading. Resuse the solution and get 2 or 3 tests in a row that agree. Only fill to the 10s. Use a quick snap of a glance or else the eyes see the dot no matter what.

We will likely raise the CYA to buffer the FC against the TX sun, but don't want to overshoot either, so we need good data.

My CYA is all over the place because I wasn't doing the test right to begin with . I read this article yesterday on how to do it correctly and even did the CYA standard solution test with the R-7065 last night to make sure I was doing it right. I would say my test last night is the most accurate at this point. I will switch to the "quick snap" technique also, because I have been starring down the tube adding water and waiting for the dot to disappear.

 

[Newdude]

even did the CYA standard solution test with the R-7065 last night

Maybe this is part of it too. Even if it was plenty bright yesterday evening, you want the sun overhead. It's such a subjective test and every little hack really matters.

The thing that gets me about this is that the dirt/algae was only on the shaded areas of the

Could be the natural circulation of the pool, coincidentally hitting a dead spot that's also in the shade. Or some similar 'looks like but isn't'. If the algae was eating FC during the day, it would do so at night. Hence the reason for the test to remove the known variable of the sun from the equation. We have proved the sun is at fault by doing so.

Now. *why* is the sun at fault ? If your CYA was Ok to match it, it wouldn't be. Maybe some trees aren't fully grown yet to help block some UV. Maybe just Texas and your April is like my August. The key is you are listening to your pool. It won't listen to you.

 

[rbwamsley]

@Newdude I appreciate all the help. At this point, I'm going to hold off on a SLAM and collect more results with daily chlorine and CYA tests and few OCLT tests. Hopefully I can get a good feel for what "normal" chlorine consumption is for my pool. Also, will watch out for possible algae.

 

[proavia]

The thing that gets me about this is that the dirt/algae was only on the shaded areas of the pool.



My CYA is all over the place because I wasn't doing the test right to begin with . I read this article yesterday on how to do it correctly and even did the CYA standard solution test with the R-7065 last night to make sure I was doing it right. I would say my test last night is the most accurate at this point. I will switch to the "quick snap" technique also, because I have been starring down the tube adding water and waiting for the dot to disappear.

If you're doing the CYA test at night, you aren't doing it right.

1. Be sure the water sample is at or above room temperature
2. Outside on a bright sunny day
3. Back to the sun
4. Fill tube to first line
5. CYA test tube at waist level in the shade of your body
6. Hold tube with only 2 fingers near top of tube to allow filtered light in
7. Glance, don't stare
8. If dot visible, fill to next line
9. Repeat 4-6 until dot isn't visible
10. Round up - if can see dot at 40 and can't see dot at 30, call CYA 40

Don't forget, you can pour the solution back into the bottle from the test tube and do the test multiple times with the same sample. Some do this three times and take the average of the readings.