Just Double Checking

[w1sp3rs]

Expecting bathers tomorrow. FC level is at 2.4. I can add regular Clorox bleach to raise the level a little, right? Salt water pool.

pH is 8.0 so I added acid to drop it. I've got a CH problem.

 

[pooldv]

Yes, we typically recommend a couple ppm above target up to half of shock level for your CYA, [FC/CYA][/FC/CYA]for a big party.

 

[w1sp3rs]

Yes, we typically recommend a couple ppm above target up to half of shock level for your CYA, [FC/CYA][/FC/CYA]for a big party.

Wow, really? My CYA was high around 150 last time I had it checked. I know I need to drain some water to fix that and the CH, but still don't have a sump pump to do it.

Your link says shock level 31ppm for a CYA of 90, which is about 16 according to your post. Where should I be with a higher CYA?

Also, my system is telling me my salt is at 2800ppm (low), but the shop said I was high around 3800. If I add the Clorox, how will that affect my salt level?


Thanks for the help!

 

[pooldv]

Chlorine level is set based on CYA and the [FC/CYA][/FC/CYA]. It must be kept above minimum at all times to keep the pool safe, sanitary and algae free. When FC drops below minimum the kill rate for bacteria, viruses and pathogens is too slow to effectively prevent person to person disease transmission. And algae can grow too.

Here is how I chlorinate. SWG and CYA at 80. I target 8. When we are going to swim all day or people are coming over to swim then I add a jug of 8.25% bleach which adds 4 ppm to my pool bringing FC up to 12 before the party. If there are extra kids I'll check it after and maybe add another jug.

It is safe swim when FC is between minimum and shock level for your CYA.

So, with CYA at 150 you can add the 100 and 50 numbers together. Which makes your minimum for sanitation 11 ppm and target 18 ppm.

 

[w1sp3rs]

Chlorine level is set based on CYA and the [FC/CYA][/FC/CYA]. It must be kept above minimum at all times to keep the pool safe, sanitary and algae free. When FC drops below minimum the kill rate for bacteria, viruses and pathogens is too slow to effectively prevent person to person disease transmission. And algae can grow too.

Here is how I chlorinate. SWG and CYA at 80. I target 8. When we are going to swim all day or people are coming over to swim then I add a jug of 8.25% bleach which adds 4 ppm to my pool bringing FC up to 12 before the party. If there are extra kids I'll check it after and maybe add another jug.

It is safe swim when FC is between minimum and shock level for your CYA.

So, with CYA at 150 you can add the 100 and 50 numbers together. Which makes your minimum for sanitation 11 ppm and target 18 ppm.

Okay thanks! The pool has always had a high CYA and I've never gone over a FC level of 6ppm, but the pool looks great and no algae. I was worried that a FC level higher than 6 ppm would start to irritate the bathers, and since everything looks fine, I didn't exceed 6 ppm.

Can I get a quick sanity check? Every time I compare my numbers, I think I'm low when they (pool shop) say I'm too high. My kit (Taylor K-2006 FAS-DPD) says to fill to 25ml, add two scoops, add drops, count them, then multiply the drops by 0.2. I did this again today and I only counted 12 drops until the sample tuned clear. That means 2.4 ppm. Seems low, but the water is really clear and I don't usually don't need to add bleach. I don't see any algae anywhere. My generator is currently set at 75% because it's so hot. Am I missing something? 18 ppm won't irritate my party? Just sounds high to me, but if TFP says so, I will follow!

 

[pooldv]

To save reagents and speed up the FAS/DPD test you can use a 10ml sample and count each drop as 0.5 ppm FC.

Did you do the diluted test to get the 150 ppm CYA?
Pool School - CYA

 

[w1sp3rs]

Sometimes I do both 10ml and 25ml just to verify. I know it's a waste, but I don't care. Just want to double check my numbers.

I did do the diluted test once because the CYA is so high and it came out to around 200 ppm. That test is difficult to gauge!

I have high TA (110), high CH (800) and high CYA. I have a real scaling problem, but again, I just haven't got around to partially draining the pool and filling with fresh water (250 ppm, CH). Pool looks great though! Just want to make sure I have enough FC for several bathers.

 

[max2k]

Okay thanks! The pool has always had a high CYA and I've never gone over a FC level of 6ppm, but the pool looks great and no algae. I was worried that a FC level higher than 6 ppm would start to irritate the bathers, and since everything looks fine, I didn't exceed 6 ppm.

Can I get a quick sanity check? Every time I compare my numbers, I think I'm low when they (pool shop) say I'm too high. My kit (Taylor K-2006 FAS-DPD) says to fill to 25ml, add two scoops, add drops, count them, then multiply the drops by 0.2. I did this again today and I only counted 12 drops until the sample tuned clear. That means 2.4 ppm. Seems low, but the water is really clear and I don't usually don't need to add bleach. I don't see any algae anywhere. My generator is currently set at 75% because it's so hot. Am I missing something? 18 ppm won't irritate my party? Just sounds high to me, but if TFP says so, I will follow!

IMO 2.4 ppm is way below anything sensible at your CYA level. I was running mine (fresh water) at 12 - 14 ppm when my CYA was close to 300. While it was also low for my CYA at the time I guess filter and running pump at low speed overnight helped so I never had algae problem. To be precise I saw small <1" patches around returns and in some corners but those were easily cleaned off during my weekly brushing. No algae bloom, green water or even cloudy water ever happened.

 

[pooldv]

I agree, doing 25ml test is good to do sometimes. No, not enough chlorine for sure. Need to drain half the pool or so and get it under control. But, you know that. We had to SLAM last summer with CYA at 70 and FC at 28. We swam every day and nobody even noticed the elevated FC.

The scale can really shorten the plaster life and isn't that hard to manage. Enter all your test results into PoolMath and it will give you a CSI score. Keep that -0.3 to 0 to prevent scale. More here, Pool School - Calcium Scaling

 

[w1sp3rs]

IMO 2.4 ppm is way below anything sensible at your CYA level. I was running mine (fresh water) at 12 - 14 ppm when my CYA was close to 300. While it was also low for my CYA at the time I guess filter and running pump at low speed overnight helped so I never had algae problem. To be precise I saw small <1" patches around returns and in some corners but those were easily cleaned off during my weekly brushing. No algae bloom, green water or even cloudy water ever happened.

Hmm. Maybe the water is so clear because I run it 5 hours a day? I just don't get why the FC level is so low, but the water looks fine. Been operating like this all summer.
Being an engineer, I'm sure I got the instructions and math right on the tests. I'm just hesitant to add 334 oz of bleach to the water in fear of irritating my guests.

 

[pooldv]

I don't understand it either. Very strange that you don't have cloudy water and algae.

 

[w1sp3rs]

Here is a picture from a couple of weeks ago. Still looks the same.

 

[pooldv]

I like it!

 

[domct203]

That's a beautiful pool!

While you might not have any algae, that FC is no where near adaquate to stop person to person transmission of diseases, pathogens and or bacteria.

Good luck with with your pool party.

Dom

 

[drywall guy]

I would look at it this way....its alot quicker and easier to get the fc reading to the proper level asap than to fix cloudy / green water later.

 

[w1sp3rs]

I would look at it this way....its alot quicker and easier to get the fc reading to the proper level asap than to fix cloudy / green water later.

Agreed. And I agree with all the other advice on this thread. I added some bleach this morning and got the FC up to 6.0 ppm. Going to and another jug.

Really appreciate all the help. Thanks, guys! Next is to fix my scaling problem.