CYA 80-100 w/ FC target at 9...is 9 safe for toddlers???

[lka674]

Hi...brand new here, so please forgive me if I'm posting under the wrong topic.

So we have a "slight" CYA problem and we know we need to drain some of the water and replenish to get it back down to the 50-70 range (currently b/w 80 & 100) with a 15K gallon pool.

According to the charts, my target FC should be around 9. I've never let my 2 year old in the water if it was above 5! Does the higher CYA allow for safe HIGHER levels of FC?

Again, so sorry if I'm under the wrong topic! Learning....

Many thanks in advance!
LK

 

[Richard320]

Yes.

The active chlorine level you're describing is actually lower than what comes out of your faucet.
This chart from chemgeek shows the equivalent values to if there was no CYA in the water.

 

[jblizzle]

Perfectly safe. In fact your pool with 9ppm FC in 90ppm CYA has a MUCH lower active chlorine amount than a public pool with 1ppm FC in 0ppm CYA.

As long as you keep the FC above the minimum for your CYA (a FC of 7ppm) and below shock level (FC of 39ppm) and your pH in mid 7s and your CC not more than 0.5ppm and the water is clear ... your pool is safe.

There are some VERY detailed discussions about this in "The Deep End" is you want all the details

 

[lka674]

Thank ya'll so much! I'll definitely check out In the Deep End. I'm sorta getting thrown to the sharks with learning all of this quickly and I'll spare ya the details.
So, we plan to lower our CYA at every backwash (just a bit more each time than necessary) rather than just dump 38% of our volume in one sha-bang due to water restrictions that are inevitable for our area, but in the meantime...I have my chlorinator set at 0 and plan to use liquid 6% bleach to bring the FC up to 7-9/ppm. Am I correct in how I'm thinking this? The chlorinator and the tabs used in it will just increase the CYA further....so try to keep that as low as possible and rather than using our standard 73% cal-hypo shock as we have in the past, if I switch to liquid it won't affect my pH either (which I also wrestle with to keep stable at around 7-5 and have to use the muriatic acid frequently to lower it)...but I'm thinking this is the case BECAUSE we've been keeping the FC too low this entire time (bw 1-5 eeeks and we were worried about our toddler being safe???)....so basically, I just need to test chemistry daily and treat accordingly until we get the pool drained a bit to lower the CYA, keep the FC at around 7-9 via liquid chlorine and the pH within normal ranges. Do I get it? At least partly?? ;-)

 

[jblizzle]

Mostly correct. And if you are new to this ... start in Pool School ... not the Deep End

Realize that 7ppm FC is the MINIMUM you should ever allow it to be ... you need to raise it up high enough that it is still above 7ppm the nest time you test and add bleach.

Tablets were adding CYA as you stated. And the cal-hypo was adding calcium.

If you are maintaining your FC daily in range ... there is not normally a reason to have to "shock" as you call it. We say the shock PROCESS as it is not a one time thing ... read up in Pool School.

As you said, you let the FC be too low for awhile. I would suggest you raise the FC up to around 20ppm, and then do an OCLT to verify that nothing is living in the pool. If you fail, then you should go through the shock PROCESS.

How are you testing your levels?

Post up a full set of results and lets see where you stand.

 

[supertune]

Perfectly safe. In fact your pool with 9ppm FC in 90ppm CYA has a MUCH lower active chlorine amount than a public pool with 1ppm FC in 0ppm CYA.

As long as you keep the FC above the minimum for your CYA (a FC of 7ppm) and below shock level (FC of 39ppm) and your pH in mid 7s and your CC not more than 0.5ppm and the water is clear ... your pool is safe.

There are some VERY detailed discussions about this in "The Deep End" is you want all the details

Yes, as long as the CC is .5 or less, I haven't seen you post that yet.
What is your TA?
The TA controls what the pH does as far as going up all the time, but also type of pool.
Read and do this too, it will help us to help you.
what-we-need-to-know-to-answer-your-questions-t10341.html

Chuck

 

[lka674]

Thanks to you both! I have those numbers written down from my DPD test that I did earlier and I'll get those back to you shortly...gotta run to go pick up that baby girl I mentioned earlier right now...will be back shortly and will post all the numbers. Jason, thanks again and I WILL start in Pool School...and I did...but sorta got WAY ahead of myself! LOL

Chuck, you as well...thanks for the info and I'll get all of those details back to ya as soon as I get back as well!

You have no idea how much I appreciate your help!!

Laura

 

[lka674]

OK....updated my profile with the stats...and here are the most current test results using a Taylor DPD test kit.

FC = 1 (this is up from 0 this a.m) when I added approx 112 oz of liquid chlorine
TC = 1
pH = 7.5 (this is AFTER I added approx 48 oz of muriatic acid this a.m)...it was WAY up....
TA = 100
CH = 450??? This is very subjective on my part b/c it was hard to tell b/w purple and blue, but I will say we live in a very HARD water area and we have to use a water softener for our home......
CYA = 64....this is amazing to me b/c when I tested it earlier (about 2 hours ago) it was 80

 

[jblizzle]

CYA can be very dependent on lighting conditions. See here for more info on the tests: extended-test-kit-directions-t25081.html

It looks like you have a decent test kit, but I would HIGHLY recommend you add the FAS-DPD chlorine test (go to tftestkits.net). It is much more accurate, which is needed for shocking purposes.

Obviously it is not good that your FC is below 7ppm (which was the minimum for CYA of ~90ppm). Even for 70ppm, the minimum is 5ppm. You need to be shooting higher between tests. Am I correct your FC test only goes up to 5ppm ... another reason for the FAS-DPD.

I would again recommend a boost to high FC level follow by an OCLT, but that is almost impossible to do accurately enough with only a color matching FC test.

 

[lka674]

Yes, you are correct that it only goes to 5....the Taylor DPD....I will look into the test kit you mentioned.

If I use the "cheating to get by test strips" AquaCheck Select, I get:

Total Hardness somewhere between 250 - 500
TC of 3
FC of 3
pH slightly "maybe" over 7.8
TA between 120 and 180
CyA 30-50

Urgh.....did I mention I HATED chemistry in HS and that was over 20 yrs ago!

 

[jblizzle]

If you add the Speedstir with the FAS-DPD test ... it becomes almost fun
With some learning and the use of the good test kit, you will soon become confident in your pool's chemistry which will actually reduce your stress level.

Ignore the strips ... trust the drop based tests.

 

[lka674]

So until I get those kits ate we in agreement that I need to dump about 250 oz of liquid chlorine??

 

[jblizzle]

That is what I get for 6% to get up to ~9ppm FC ... no telling on how fast it will drop though.

You can try to use a 50/50 mix of pool and distilled water in your test and double the reading ... it looses some accuracy, but you could try to keep the FC roughly above 10ppm.

Unfortunately too, finding the FAS-DPD test locally is rarely possible ... most pool stores look at you like you are crazy that you think you need it or have no idea what you are talking about.

 

[lka674]

Thanks Jason! I'll let ya know the new #'s once I order those new kits...and I don't care how they look at me! ;-)

 

[wes8398]

http://standards.nsf.org/apps/group_public/download.php?document_id=5891 The bottom of page 5 and top of page 6, along with the paragraphs surrounding them give another form of the cya/fc relationship. I've recently been looking into this, as I wasn't comfortable having swimmers with 15ppm FC readings. With my ~50-60ppm CYA though, these charts would have me believe that a FC of 15ppm is absolutely fine.

 

[linen]

So until I get those kits ate we in agreement that I need to dump about 250 oz of liquid chlorine??

Liquid chlorine typically refers to either 10%, of 12.5% Sodium Hypochlorite. If that is what you are refereing to, you need to cut your volume about in half. If you are referring to regular household bleach (6% Sodium Hypochlorite), then I get 250 ounces 6% bleach for you 15000 gallon pool to go from 1 to 9 ppm FC. But if it is Liquid Chlorine at 12.5%, then I get 119 ounces to go from 1- 9 ppm FC.

 

[linen]

http://standards.nsf.org/apps/group_public/download.php?document_id=5891 The bottom of page 5 and top of page 6, along with the paragraphs surrounding them give another form of the cya/fc relationship. I've recently been looking into this, as I wasn't comfortable having swimmers with 15ppm FC readings. With my ~50-60ppm CYA though, these charts would have me believe that a FC of 15ppm is absolutely fine.

FYI, the author of that paper is Richard Falk, known as "chem geek" who is a "special contributor" on this forum and some of the Chlorine/cya chart in pool school is his work (along with a lot of other stuff on here).

 

[wes8398]

FYI, the author of that paper is Richard Falk, known as "chem geek" who is a "special contributor" on this forum and some of the Chlorine/cya chart in pool school is his work (along with a lot of other stuff on here).

I was aware of that. I didn't think I had to re-credit him for the link since it went directly to his paper and not just an unidentifiable excerpt.

 

[lka674]

So until I get those kits ate we in agreement that I need to dump about 250 oz of liquid chlorine??

Liquid chlorine typically refers to either 10%, of 12.5% Sodium Hypochlorite. If that is what you are refereing to, you need to cut your volume about in half. If you are referring to regular household bleach (6% Sodium Hypochlorite), then I get 250 ounces 6% bleach for you 15000 gallon pool to go from 1 to 9 ppm FC. But if it is Liquid Chlorine at 12.5%, then I get 119 ounces to go from 1- 9 ppm FC.

Yes, I did use 6% household bleach and it did bring it up to 9ppm FC. I'm headed out today to get a better kit based upon what I've been learning on this forum.
Quick question though...the bleach caused this soapy bubble reaction from my spa's spillway when it hit the pool water...is that normal with bleach? When I've used liquid chlorine I don't get that soapy bubble look at the entry to the pool from the spillway. Also, how long after using bleach or liquid chlorine should you wait to allow swimmers? I'm not shocking, just raising it to be more sanitized based upon my CYA readings....you'd think it was safe as soon as you reach the desired level, but last night I got in it about 3 hrs after increasing it (just to see what, if any, my reaction to it would be when FC was at 9ppm) and I could barely stand the smell/fumes and it sorta did make my skin irritated.

Thanks again to everyone who has given me excellent advice!

 

[linen]

If you can smell the chlorine and it bothers your skin, most likely it is CC. CC reading higher than 0.5 ppm means you need to do the shocking process.

What is your CC level?

Quick question though...the bleach caused this soapy bubble reaction from my spa's spillway when it hit the pool water...is that normal with bleach?

No, this is not normal and might be a sign you have algae.

Also, how long after using bleach or liquid chlorine should you wait to allow swimmers?

I would wait 1/2 hour.