Generally safe to swim in clear water?

Dpooltest

Well-known member
May 28, 2019
48
New york
I know you shouldn’t swim in a green pool, or otherwise non clear water, but I’d it safe to swim in water that is clear otherwise? I know lots of people with pools and must do what the pool store said or other non TFP methods. I see a bunch of posts about Oclt and if you fail there may still be a problem even if water is clear. In this case is it still ok to swim in the pool, should I worry about other pools?
 

Yev

Well-known member
Jul 29, 2014
408
Independence, KY
exactly mknauss.

While over a multiday course, having insufficient FC levels based upon CYA will make maintaining clarity pracitcally impossible, on a single day this is very possible. As an example, lets say that you started the day at the bare minimum acceptable level of FC based upon your FC, have a full day of sun, and a pool full of swimmers without adding more chlorine, you will quickly be under the minimum amount of FC. Once this happens you can enter the danger zone for having germs in the water that could spread despite the water being clear.

I might suggest that in the world today where germs are a concern to many people, start a day of swimming with the high end of your FC target just to be safe. And dont be scared to check during a party. If you have to, add some chlorine while everyone is taking a quick lunch break out of the pool.
 
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Msch99

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Bronze Supporter
Jun 11, 2018
680
Verona, MO
That's the problem with following TFP - you do start to worry about other pools ;)
Yup. No more hotel pools for grandkids. (Actually we look for hotels without pools or couldn’t keep grandkids out. ) My daughter was shocked when I explained the smell to her.
 

lager1829

Gold Supporter
Jul 8, 2015
107
Lancaster County, PA
That's the problem with following TFP - you do start to worry about other pools ;)
So true. And feeling vindicated when the local news reports this (last year):

How dirty are Lancaster County's pools? Nearly 1 in 3 report bacterial failure that can cause sickness

The failures include 10 of the 29 swimming pools run by local governments or community organizations in Adamstown, Hempfield, Leola, Lititz, East Petersburg, Ephrata, New Holland and southern Lancaster County.

The worst offenders are among privately run campgrounds, hotels and condominium associations. Privately run pools accounted for 116 of the 135 bacterial failures — or 86 percent — in 2018, according to the Department of Health.
 
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Dpooltest

Well-known member
May 28, 2019
48
New york
I’m also still learning this stuff myself, I was under the assumption that the pool math app guidelines were ok, meaning FC 1-4 is ok, so if I drift to 1 at the end of day (or lower it would be fine, not realizing I should really try to stay at 2 or higher). Now I’m aiming for FC of 4 rather than 3.
 

mgtfp

Bronze Supporter
Mar 5, 2020
168
Melbourne, Australia
The FC guidelines here are designed to keep algae in check. The lower limit really is the absolute minimum you should never get under so you don't risk algae growth. You should always aim to have a safety buffer to account for testing errors, low circulation patches in the pool, or just unexpected events (work, kids sick, etc) where you can't top up with bleach when you planned for.

If your pool really doesn't have any algae, then going occasionally down to or even slightly below the minimum won't trigger an instant algae bloom. But if you already have algae in the water then going lower might let them thrive. That's where brushing is important.

If you are not that thorough with your brushing then staying towards the upper end of the recommended range would be a good idea.

But even at the TFP minimum you would still have some safety margin to keep the water safe. Most pathogens are killed very quickly even with low levels of chlorine. There are some exceptions, but that's another story.

As long as only your family is using the pool, person to person transmission is usually not a problem, because your are exposed to each other's germs anyway, you just need to make sure that germs get killed reasonably fast. But when having other people in the pool then you really want very fast bacteria kill times to avoid person to person transmission in the water. And you want to make sure that e.g. bird droppings get sanitized quickly.

But as mentioned by others already, just because the water is clear, doesn't mean it's necessarily safe. Bacteria grow much faster than algae, should the FC be too low.
 

Yev

Well-known member
Jul 29, 2014
408
Independence, KY
I’m also still learning this stuff myself, I was under the assumption that the pool math app guidelines were ok, meaning FC 1-4 is ok, so if I drift to 1 at the end of day (or lower it would be fine, not realizing I should really try to stay at 2 or higher). Now I’m aiming for FC of 4 rather than 3.
I have always thought that the target range was bad wording, but cant figure out how I would do it better. If my range es 1-4 as in your example, mentally I think it should be 3-4, with a separate target called danger zone at 1. Or maybe Max=5, Goal =4, and danger zone=1
 

Dpooltest

Well-known member
May 28, 2019
48
New york
Ok so regarding FC, I probably misinterpreted what I read. Is the safe swim limit dependent on cya? I thought 5 and up was no swim, but after looking at the chart it looks like 5 is actually desirable for certain cya levels, so Is the safe FC level the upper limit of the recommended range, or just below slam?

for example
With cya at 30 is it safe to swim at an FC of 7-10( like if I was having a kids bday party)

cyamin FCrec FCSlam
3024-612
 

mgtfp

Bronze Supporter
Mar 5, 2020
168
Melbourne, Australia
... but you need to be able to trust the CYA measurement, and the FC measurement. I wouldn't swim in a pool that got bumped up to SLAM level for CYA=100ppm based on a pool store CYA test.
 

Msch99

Gold Supporter
Bronze Supporter
Jun 11, 2018
680
Verona, MO
When I know grandkids having a swim party, I add CL so I’m a couple points over high target. My cya 70 so I bump to 12 or so 30 minutes ahead if I can.
 

mgtfp

Bronze Supporter
Mar 5, 2020
168
Melbourne, Australia
... and one thing to consider is the reason why you are SLAMming. Usually you are at that level because you are fighting something. And that something will create CC. It's the CC that is usually creating discomfort like red eyes and so on, not the FC. So while you are still fighting algae, I wouldn't swim, also because you will distract your chlorine from killing algae.

But once you passed all criteria to end the SLAM, you can swim while waiting for FC to come down. Or if you decide to maintain higher FC up to SLAM for whatever reason, you can still swim.
 
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