Safe Free Chlorine Levels for swimming?

[newfool]

LOL, that's my life.

Anyway - the FC according to the dpd test was 3.5 this morning after being at 23.5 - so 20ppm of chlorine were consumed from sunday night to wednesday morning - yeah there must have been algae ;-) I put another 2.5g of liquid chlorine in at around noontime and of course it rains today... The pool looks clearer, I hope with this shock I can get things corrected.

Should I test again tomorrow or wait until later?

I did a little maintenance today, the pool is 6 years old so I figured I should give all the equipment a good once over. I ended up replacing the pressure gauge - the needle was sticking and the backplate was corroded. I noticed that when I replaced the gauge, the pressure reading was 20 psi! I had just cleaned the filter about a month ago so I was shocked. I took out the filter and gave it another cleaning, this time instead of soap and water, I used a dilute muriatic acid wash and rinsed off after a few minutes. Pressure came down to 9psi. I checked a few hours later and it had climbed back to 12psi! I looked to see when I purchased the last filter and it was in 2010!! Holy cow, time flies right! I guess its time for a new filter.

How long do you get out of your filters?

 

[jblizzle]

You should be using and adjusting the FC level at least twice a day ... Have you reviewed the SLAM process?

What does the water look like? Sounds like the filter is doing it's job and capturing stuff.

 

[newfool]

No, the SLAM is news to me - makes sense. I had been following the BBB method since I built the pool and never had many issues. The biggest problem for me is not being able to service the pool weekly.

The CC was 0.5 yesterday morning, so I guess I am heading in the right direction. I will check the FC/CC this morning and see, I didn't have the pump running all night, that would have been a good idea I usually wont throw the vac in when I am shocking, but I will brush the walls down. Thanks for the info!

Update: I checked the FC/CC and got 26 with no CC! Nice overnight, eh? Interestingly enough, the pressure gauge now reads 20 psi again. From 9psi just cleaned, to 12 psi in a few hours and now 24 hours later up to 20psi! I was going to add some DE, but I think I will wait until the new filter gets here before I add it. I don't want the pressure to get jacked up further and then not be able to do anything about it. Should be interesting to see the difference in psi that a charge of DE causes on an old filter then the new.

 

[rterickson]

At my previous pool with a cartridge filter, rapid pressure rise was a sure sign that I was in need of a new filter. I never got more than 3 years out of one, but I had trees with a lot of tiny pointy leaves poolside.

One thing that helped extend the life was taking a pocketful for quarters to the do-it-yerself car wash place, and using the pressure wand full blast (water only). *Tons* of sediment and dirt would come out.

 

[jblizzle]

One thing that helped extend the life was taking a pocketful for quarters to the do-it-yerself car wash place, and using the pressure wand full blast (water only). *Tons* of sediment and dirt would come out.

That sounds like it would do more damage than good to the cartridge.

 

[mkmscr]

So in my situation the pool chems are below. What I would like to know is it safe for my family and pets to swim (FC 15ppm CYA 70) or do I need to wait for it to come down and if so what level is safe for swimming? And I am sure you're wondering how my FC climbed so high and that's because I left my SWG in Boost mode for like 5 days straight accidentally so it was cranking out the chlorine until I realized I left it on....DOH. Also the FC seems to be taking forever to come down but I have been leaving a solar blanket on so does that help keep FC in the pool because the suns not chewing it up as fast?

FC 15ppm
CC 0
PH 7.6
TA 80
CYA 70

 

[chem geek]

You can safely swim. Your FC is well below the SLAM level of 28 ppm. You may notice a little chlorine smell but the active chlorine level in your pool is less than a pool with 0.25 ppm FC with no CYA (or 0.5 ppm FC and no CYA if the pool is warm at 88ºF) so less than half the lowest level found in commercial/public indoor pools.

Yes, having a cover that is at least partially opaque to the UV in sunlight will significantly reduce the rate of chlorine loss.

 

[GregoryRG]

how about 2 or 3 ppm over SLAM level (28 in my case, SWG, CYA of 75-ish per the TF-100 test)? My wife is upset that I want to keep the kids out of the pool while SLAMing away whatever is eating 3 ppm FC per day. She doesn't "believe" that I need to maintain the shock level or don't bother.

Any thoughts? I've digested most of threads I could find in the forum on this and the consensus (if there is one), is anything below the Shock level for your CYA value is safe).

 

[jblizzle]

The higher the FC the harsher the water.

 

[chem geek]

The regular SLAM level has the same active chlorine level as a pool with 0.6 ppm FC and no CYA. So it's less than commercial/public pools with no CYA such as indoor pools. It's roughly 10 times the active chlorine level as the minimum FC/CYA level. So think of being in the water for one swim day as being equivalent to being in the pool at normal (minimum) levels for 10 days. So up to you if you want to have the kids in the pool. People will likely notice more chlorine and chloramine smell since chlorine will react and outgas faster.

The FC level itself becomes relevant if you were to drink a lot of pool water. The EPA limit is 4 ppm FC for drinking water assuming consumption of 2 quarts per day for a lifetime. So 28 ppm FC is 7 times this limit so if you drank 4.6 fluid ounces (somewhat more than half a cup) of pool water you'd be at your daily limit according to the EPA drinking water standards (see this link), but according to the EPA in this link, the No Observed Adverse Effect Level (NOAEL) for long-term consumption is 14.4 mg/kg/day in rats but with the factor of 100 margin of exposure this gets down to 0.1 mg/kg/day. For a 20 kg (44 pound) child, this would require drinking 0.07 liters (2.4 fluid ounces) per day of 28 ppm FC water.

 

[Silver_2000]

I know its an old thread but Im dying to get in my pool. The water temps should hit mid 70s today
I was a little tardy with chlorine earlier in the week so I did my version of a shock or slam to get some of the green algea that had developed in the corners of the spa and the step.
My CYA is likely close to zero due to 5000-8000 gallon a month leak, and the rains / storms this week
Ive been using pucks but I havent added any stablizer since the replaster will wash any chemical dollars down the drain
This thread helps me understand that if the water is clear ( it is ) and the FC isnt crazy Ill be ok
Yesterday the Quick yellow reagent test showed the chlorine off the chart but the drop test showed FC about 6 and the CC at zero
Thanks again to the resource here

 

[pabeader]

Pucks add stabilizer. You can guess how much from the number you have used. But it's best to measure it with your TF-100 test kit and then you will know for sure.

 

[Silver_2000]

I measured it and it was between 25 and 30
Since Ive had 3 or 4 pucks in the pool for the last 2 months that shows that Im still losing water