Chlorine FC 10 to zero in 2.5 days (w/ Pics)

[NoodleGirl]

Hey all - I was getting a hang of the pool stuff but I think I need help… the past week chlorine FC levels have been dropping fast.

9:30am on 6/13, zero FC chlorine

10:30am on 6/13, added 3 gallons of liquid chorine at 10% bleach. Sand filter backwashed

Noon on 6/15, zero FC chlorine, 0.5 maybe of CC, hardness 175, alkalinity 75, pH 7.8, CYA I think at 30

I have 7 gallons of 10% bleach on hand and 4 lbs of stabilizer. I would like to try and do what I can this afternoon as I can’t leave the house.

Per pool math to get to 10 FC, I’ll add 3 gallons bleach, then a few hours later can I start adding about 4 lbs of stabilizer? Then later tonight I will backwash filter again. Keep backwashing all week and doing FC testing.

Anyone feel different about these CYA readings per the TF-Pro test kit?

Any other advice or can I proceed?

 

[dBsooner]

Then later tonight I will backwash filter again. Keep backwashing all week and doing FC testing

Why are you backwashing so often? You only need to backwash when your filter pressure rises 25% from "clean" baseline (what your psi is right after you finish a backwash and rinse).

Per pool math to get to 10 FC

I assume you are you trying to SLAM? Even then, 30 CYA would be 12 FC. IF you are just maintaining, your minimum is 2 with a target of 4-6. 40 CYA would be min 3 and target 5-7.

Anyone feel different about these CYA readings per the TF-Pro test kit?

You need to make sure you are doing the CYA test outside on a bright day. Indoor lighting isn't bright enough. Best time is from 11am to 4pm outdoors. Also, just to be sure, you are holding the cylinder at waist level and looking down. Don't "stare" for the dot. Just glance for it.

 

[HermanTX]

I would call your CYA 40 - as you would look from about 2.5 ft above it - hold at your waist level and look down.
You can start adding stabilizer to increase to 60. Do it in stages. Also it takes 24-48 hrs to register on the test.
I think that is why your FC is dropping. With the heat in the south, the FC loss is pretty high right now.
Not sure why you are backwashing so much.

 

[randytsuch]

I'd recommend an OCLT

You might have organics or something eating up your chlorine.

If you fail the test, time to SLAM.

IMHO, I would not add CYA until after the OCLT. If you need to SLAM, its easier with less CYA.

Randy

 

[NoodleGirl]

Hey @HermanTX and @dBsooner - thank you!!
- I backwashed on Tuesday because PSI was at 30 and normally is 10.
—should I only backwash when it’s gets super high or whenever I’m trying to get things pristine?
- Yes, I was trying to SLAM as water is slightly cloudy and the fact that I lost all that chlorine so fast freaked me out.
- Thanks on the 40 CYA input, I just did it in bright light a second ago again from 2.5 feet away. (Pics attached)
- I’ve tried doing the CYA test out in the sun a few weeks ago but I got the same results. I’m probably looking too hard lol.
- I was assuming I was somewhere between 20-30 CYA, but I’ll proceed with the assumption of 40 CYA!! Thank you!
- And yes, about to go into a really hot weekend!

I’ll try and pick up more liquid chlorine and stabilizer in the next few days so I have it on hand!

 

[NoodleGirl]

I'd recommend an OCLT

You might have organics or something eating up your chlorine.

If you fail the test, time to SLAM.

IMHO, I would not add CYA until after the OCLT. If you need to SLAM, its easier with less CYA.

Randy

Hey! Thanks for the advice, so on Tuesday and Wednesday (rainy) it wasn’t very sunny. Adding 3 gallons of chlorine to reach 10 FC levels and 2.5 days later FC should have not dropped to zero…right?

I was thinking because of that I should just proceed with the SLAM, and not do an overnight test?

I of course want the pool swimmable again as fast as possible haha!

 

[dBsooner]

should I only backwash when it’s gets super high or whenever I’m trying to get things pristine?

Only backwash when the pressure rises 25% from baseline. If you baseline is "10", then you would backwash when it reached 12-13.

Yes, I was trying to SLAM as water is slightly cloudy and the fact that I lost all that chlorine so fast freaked me out.

In the heat of the summer with full UV, you can lose several ppm of chlorine in a day. Without an SWG, you MUST test your water daily and add chlorine. Every day. If you ever fall below the minimum FC for your CYA level, algae will begin to grow.

Thanks on the 40 CYA input, I just did it in bright light a second ago again from 2.5 feet away. (Pics attached)

Unfortunately, pics don't help too much as they are a snapshot in time and the camera lens will not show the same results as the human eyeball being affected by all the elements. THis is one of those tests you just have to do multiple times test trust yourself on it. Have a friend / family member do the same test and see if their results are the same as you get. You can use the same solution over and over.

 

[dBsooner]

Adding 3 gallons of chlorine to reach 10 FC levels and 2.5 days later

You need to test daily.

I was thinking because of that I should just proceed with the SLAM, and not do an overnight test?

You do the OCLT to tell if you if you NEED to SLAM. If you pass OCLT, no sense in wasting the time and money on a SLAM.

I of course want the pool swimmable again as fast as possible haha!

Unless you can't see the bottom, I don't see why the pool wouldn't be swimmable. It's obviously not choked green with algae.

 

[NoodleGirl]

@dBsooner Thank you!

Just about my pool in general, I get a lot of debris in the pool (lots of plants and various trees)and sunlight is on it 11am-5pm and then mainly shaded.

- My filter definitely goes over 25% extremely quickly, because of this I assume you are saying every time I backwash I’m losing chemicals/water and need to be more aware of that? I have a new pressure reader, so my sand filter could also just be not doing so good.
- Do you think I should add enough chlorine now for a 40 CYA pool (2pm) to get in regular range and then do the overnight test tonight? Maybe it is sunlight? And start with stabilizer tomorrow regardless?

I just order the standard 50 CYA solution from TFP, so I feel more secure in my readings!

I will get better with more frequent readings!!!

And to your above message, I like the idea that I can still swim, haha thank you!

 

[dBsooner]

My filter definitely goes over 25% extremely quickly

How fast is "extremely quickly"? How old is the sand / when was the last time you did a DEEP CLEAN of the sand filter? Get a good deep clean to get that sand nice and fresh.

every time I backwash I’m losing chemicals/water

Yes. But testing FC daily will be the key here. Just test your FC at least 30 minutes after you backwash and/or use fill water.

Do you think I should add enough chlorine now for a 40 CYA pool (2pm)

Yes. Get yourself to recommend range ASAP. You don't want to play kissy face with the minimum FC for too long.

do the overnight test tonight

Yes. But print out the OCLT directions, read them three times, keep them with you. Do them exactly as they say.

Maybe it is sunlight

That's why the OCLT test is crucial.

And start with stabilizer tomorrow regardless

I'd wait. SLAM at higher CYA is hard. Let's see what your OCLT shows first.

 

[NoodleGirl]

How fast is "extremely quickly"? How old is the sand / when was the last time you did a DEEP CLEAN of the sand filter? Get a good deep clean to get that sand nice and fresh.

Yes. But testing FC daily will be the key here. Just test your FC at least 30 minutes after you backwash and/or use fill water.

Yes. Get yourself to recommend range ASAP. You don't want to play kissy face with the minimum FC for too long.

Yes. But print out the OCLT directions, read them three times, keep them with you. Do them exactly as they say.

That's why the OCLT test is crucial.

I'd wait. SLAM at higher CYA is hard. Let's see what your OCLT shows first.

I will put deep clean filter on my to do list then!! This is a new house and I did not get that info from prior owner, I’ve only had the pool open for 2 months!

Thank you for all the advice!

 

[dBsooner]

I will put deep clean filter on my to do list then!! This is a new house and I did not get that info from prior owner, I’ve only had the pool open for 2 months!

Thank you for all the advice!

Good deal! And no problem! Keep us updated. It's not as fun when we just work on our own pools. LOL.

 

[PoolStored]

I was assuming I was somewhere between 20-30 CYA, but I’ll proceed with the assumption of 40 CYA!! Thank you!

Based on your pictures, your CYA is likely 10-20. Your CYA is low and UV is eating up your chlorine.

Chlorine in water without CYA has a half life of 35minutes. Wait 2 hours and less than 5% will be left. You need to get that CYA up...

 

[NoodleGirl]

Hey all, I did the overnight test. At 3pm I added 2 gallons 10% bleach. At 10pm FC was at 2.5 and this morning at 8:30am it was at 1.5.

I’m going to proceed with adding 2 lbs of stabilizer just to get levels up to see if that helps. Off to find socks!

 

[jsygrls]

Based on your pictures, your CYA is likely 10-20. Your CYA is low and UV is eating up your chlorine.

Chlorine in water without CYA has a half life of 35minutes. Wait 2 hours and less than 5% will be left. You need to get that CYA up...

poolstored got you on the right path

 

[PoolStored]

Hey all, I did the overnight test. At 3pm I added 2 gallons 10% bleach. At 10pm FC was at 2.5 and this morning at 8:30am it was at 1.5.

Ideally, you want your OCLT to start with at least 3ppm.

 

[dBsooner]

2.5 and 1.5ppm: That's dangerously low. If your CYA is where PoolStored figured it is at, then you're within a whisker of that minimum FC. If it's any more than 20 ppm, you're below minimum. You need chlorine! Which I know you added 2 gallons. That's going to raise you by 6.2 for 32000 gallons. Putting you around 7.5ish. If you're that low (10-20 ppm CYA), you're going to burn off that FC very quickly today as it appears it's going to be mostly sunny in northern Alabama today. I would suspect you're gonna lose a majority of that by this afternoon.

I am not sure which direction @PoolStored wants you to go now. I'm sure he'll follow up. LOL. Since, like he said, OCLT would be best to start with at least 3 ppm. What I would do is do a quick 5ml sample test (1 drop = 1 ppm) after sundown. Then add enough LC to get me into the middle of my target range. Wait 45 minutes to an hour (30 is the recommended time, but I would watch an episode of the Blacklist or something), then retest with a 10ml sample size (1 drop = .5 ppm) to get my night reading for my OCLT. Then I'd get out there around 630 for my OCLT morning reading using a 10ml sample size.

But I don't know if he would rather you raise your CYA first, then deal with the OCLT or try the OCLT again. I am assuming the former as he has said before already. So you're probably on the right path by adding 2 lbs of dry stabilizer... PS: That's only going to raise your CYA by 7.5.

 

[PoolStored]

Given the haze in the water, the fact that you were at 0 FC, I'd SLAM...Link-->SLAM Process

Add 20ppm of stabilizer, use 10FC for your SLAM target. When the stabilizer is dissolved, use FC 12 for your target.

 

[HermanTX]

Hey all, I did the overnight test. At 3pm I added 2 gallons 10% bleach. At 10pm FC was at 2.5 and this morning at 8:30am it was at 1.5.

2 gallons of LC would have added 6ppm of FC. So in 7 hrs you lost at least 3.5ppm which is a mixture of UV and most likely algae. Then another 1ppm loss overnight due solely to the algae.

I’m going to proceed with adding 2 lbs of stabilizer just to get levels up to see if that helps. Off to find socks!

Your CYA is at 30 (at least on the last photo where the dot was barely visible). Doing a SLAM at 30 or max 40 CYA is recommended. You will need more LC to raise your FC to 12 or 16ppm respectively.
2 lbs of dry stabilizer could raise your CYA by another 8ppm so be careful not to exceed 40ppm

 

[NoodleGirl]

Hey all! I had a busy day but at noon today I was able to put in socks full of of 4 lbs total of stabilizer and also threw 1 gallon of 10% LC in.

I did a chlorine drop test tonight at midnight and it was 3.5 FC and to me the CYA looked more like ~35-40 (but it was night with just interior lighting). I will keep testing the CYA this weekend in the sunlight and post pics!

I plan to test again tomorrow morning at 8am.

Goodnight!