science behind salt-CYA verses liquid bleach/cya connection-cost, health, science

Here's some PoolMath to look at -

poolmathimage.jpg

If you pushed your TA down to 60ppm and increased your CYA to 80ppm, then your pH can ride between 7.6 and 7.8 and your CSI will be perfectly balanced. No scaling will occur at all. IN the hot AZ climate, we have to add acid very frequently, especially with SWG pools and our hard water, to keep the TA down and the pH balanced. But, if you're conscientious about it, do all your own testing, and, most importantly, stay OUT of the pool store with their lousy advice, you can easily keep your pool clean and clear.
 
matt and domct203, yes, I meant CSI, sorry. In a rush today but wanting to make sure I make my pool a priority.

CYA= 70. maybe. I'm surely getting this test wrong. could be way under. this test isn't the easiest for me.

even though my cell is plugged up with calcium and not working i am trying to stabilize my pH and TA. If I have algae I still should take care of that shouldn't I?

I didn't see the overnight test under black algae but I've done it before. I'll do it tonight and let u know.

In the meantime i'll check my pH a bit but if it's really low is it ok if i wait till the afternoon to go to target to get borax or do i need to make sure to do it now?

aerating pool now

matt, i don't know how u do it only adding acid once a week... i'm doing something really wrong. maybe it's my cya numbers being off? would that effect pH rise? calcium building up in cell?
thx!

- - - Updated - - -

matt and domct203, yes, I meant CSI, sorry. In a rush today but wanting to make sure I make my pool a priority.

CYA= 70. maybe. I'm surely getting this test wrong. could be way under. this test isn't the easiest for me.

even though my cell is plugged up with calcium and not working i am trying to stabilize my pH and TA. If I have algae I still should take care of that shouldn't I?

I didn't see the overnight test under black algae but I've done it before. I'll do it tonight and let u know.

In the meantime i'll check my pH a bit but if it's really low is it ok if i wait till the afternoon to go to target to get borax or do i need to make sure to do it now?

aerating pool now

matt, i don't know how u do it only adding acid once a week... i'm doing something really wrong. maybe it's my cya numbers being off? would that effect pH rise? calcium building up in cell?
thx!
 
A couple of points -

1. Black algae is not very common around here. Who told you had black algae and were you able to confirm it? It is very easy to mistake common algae with BA and the treatments are different.

2. Aerating a pool to restore pH quickly is a slow process, a couple of days likely. Just keep an eye on pH and, as soon as it hits 7.6, knock it back down again to 7.2. Each addition of acid that takes the pH from 7.6 to 7.2 should take 10ppm off your TA. Aeration simply raises pH a little quicker than leaving the water still. Swimming helps with aeration too!

3. Get a handle on your CYA. I know the test is difficult to do but it's important. The way to do it is with your back to the sun at noon when it is highest in the sky and the light is very bright (do not wear sunglasses). Hold the tube waist high in the shadow cast by your body and only hold the tube with two fingers at the top - the point is you don't want to occlude the tube. I find that the testing block that comes with a K-2006 is better than the CYA tube in the TF-100 but everyone has their preference. Mix up the test solution - 1:1 volumes of pool water and R-0013 (in the K-2006 kit, it's 7.5mL of pool water and 7.5mL of R-0013). Invert to mix for 30 secs, then let it sit for 30 secs. Give it one more inversion and then fill the test cell up slowly until the dot just disappears. DO NOT SQUINT OR USE ONE EYE. Look away periodically as you fill so your eyes are not fixating on the dot (your brain will play tricks on you). Reuse the same solution in the test cell and do the test 3 or 4 times. Average the results and ALWAYS round up to the nearest 10ppm.

I add acid every 10-14 days, lately it's been about 9 days but that's because my CH is so high and I need to maintain lower pH levels. But, I keep everything nice and balanced. Once you get a handle on your pool water you ca think about adding borates as that can help a lot.
 
My pH is 7.2. I think what I did was insert the correct #s but then to find out what i think the CSI is I play around with the "now" # of pH and move around other numbers a bit just in case I'm not measuring right, like CYA so that I know how much acid to use. I think I had changed the "now" pH number and didn't realize it as I'm rushing around.

black algae: Matches what TFPs says. looks like a black spot and when i take my fingernail green comes off. looked like moss on my fingernail but on the pebble it looked black. What's BA?

thx for all the info!
 
BA is just shorthand for "black algae".

Ok, so do the overnight chlorine loss test to make sure you're water is clear and sanitary. If it is, then just keep the FC elevated as the Black Algae pool school article says. FC can be lowered slowly over time. The water is swimmable all the way up to shock FC values but some people (like me) don't like elevated chlorine levels so swimmers will just have to figure out what's comfortable with them.

As you lower the TA you're going to see it takes longer and longer for the pH to rebound. That's the effect you're looking for. Once you get your TA down to 60ppm, you should see more pH stability.

You said the SWG cell was scaled with calcium, did you clean it yet?
 
BA is just shorthand for "black algae".

Ok, so do the overnight chlorine loss test to make sure you're water is clear and sanitary. If it is, then just keep the FC elevated as the Black Algae pool school article says. FC can be lowered slowly over time. The water is swimmable all the way up to shock FC values but some people (like me) don't like elevated chlorine levels so swimmers will just have to figure out what's comfortable with them.

As you lower the TA you're going to see it takes longer and longer for the pH to rebound. That's the effect you're looking for. Once you get your TA down to 60ppm, you should see more pH stability.

You said the SWG cell was scaled with calcium, did you clean it yet?
I went out to measure FC and I realized pump was on so i'll give it half hour just in case salt cell is producing any chlorine. I unplugged the salt cell for the night.

I figured the TA went up cuz noone swam in it a couple days but we went in today and it was cold! end of the season is soon so i'll have to get in the habit of checking TA and using the bubbler over the winter (will i need to do this in the winter, too?).

I am waiting on my husband to help clean the salt cell. I just don't have the strength. it's killing me cuz when i went away for the 2 days he didn't add chlorine the one day and he didn't clean the cell like i asked him. it usually takes a couple weeks to get him to help me which is why we end up in this mess each time. we have a strap to take the salt cell off so i was trying to learn how to use it last time. or maybe i could do it with a pipe wrench?

thx again!
 
FC last night around 8:30pm=8.5 (17drops)
FC this morn 7am = 6.5 (13 drops)

ok. doesn't look good but i want to try it again tonight just in case i didn't do it right. i don't want to SLAM if i dont' have to. really i should've gotten up earlier to check FC. I don't think sun got on the pool but I want to make sure since it's our last days of swimming for the season. Also, I used up one bottle R-0871 and began a new one in the middle of testing. I'm probably in denial but wanting to wait another day to make sure to make sure I did it right.

So, if these numbers are right, does this mean it's green algae for sure?
is that ok if i wait to slam? does that mean it's messing up pH #s/calcium and everything else?

thx!
 
FC last night around 8:30pm=8.5 (17drops)
FC this morn 7am = 6.5 (13 drops)

ok. doesn't look good but i want to try it again tonight just in case i didn't do it right. i don't want to SLAM if i dont' have to. really i should've gotten up earlier to check FC. I don't think sun got on the pool but I want to make sure since it's our last days of swimming for the season. Also, I used up one bottle R-0871 and began a new one in the middle of testing. I'm probably in denial but wanting to wait another day to make sure to make sure I did it right.

So, if these numbers are right, does this mean it's green algae for sure?
is that ok if i wait to slam? does that mean it's messing up pH #s/calcium and everything else?

thx!

Honestly, I think you have algae issues. It would explain why you have to run your SWG so hard all the time; honestly speaking, you shouldn't have to run a T-15 cell at 100% for your size pool. Running it hard like that is what causes all that scaling in the cell too.

You can try the OCLT again, but I don't think the results are going to be any better. Start looking for good prices on liquid chlorine or bleach, because you're going to need it. I would stay out of the pool store and check around hardware stores or Walmarts. 10% liquid chlorine is what you want if you can find it.
 
By the way, given that your water is clear and you're only seeing a 2ppm overnight loss, SLAM'ing the pool shouldn't be a big deal and I would predict that you'll only need a weekend to do it. Green swamps take a long time to clear; minor algae issues causing overnight loss typically resolve a lot faster....
 
Honestly, I think you have algae issues. It would explain why you have to run your SWG so hard all the time; honestly speaking, you shouldn't have to run a T-15 cell at 100% for your size pool. Running it hard like that is what causes all that scaling in the cell too.

You can try the OCLT again, but I don't think the results are going to be any better. Start looking for good prices on liquid chlorine or bleach, because you're going to need it. I would stay out of the pool store and check around hardware stores or Walmarts. 10% liquid chlorine is what you want if you can find it.

ok, so if algae problems are the cause of scaling that's excellent to know. I went to walmart recently and they said they don't sell pool chlorine any more until next summer. crazy. I got 6 bottles this week at the pool store. i'll consider home depot or aces if i need more. i'll review SLAM. i was planning on cleaning the cell today. should i wait? thx!

- - - Updated - - -

I was also wondering, why would i have 0 CCs if I have algae?
 

Enjoying this content?

Support TFP with a donation.

Give Support
ok, so if algae problems are the cause of scaling that's excellent to know. I went to walmart recently and they said they don't sell pool chlorine any more until next summer. crazy. I got 6 bottles this week at the pool store. i'll consider home depot or aces if i need more. i'll review SLAM. i was planning on cleaning the cell today. should i wait? thx!

- - - Updated - - -

I was also wondering, why would i have 0 CCs if I have algae?

should i unplug my salt cell for now to not cause further build-up...?

Algae causes low FC (the FC is consumed destroying algae) which leads the pool owner to think the cell output needs to be increased. The vicious cycle continues until the pool owner maxes out their SWG output. Once you start running your cell at 100% output all the time, scaling is inevitable.

The cell is useless during a SLAM. Just turn it off for now and deal with it later.

CC's are mostly caused by bather waste from the chlorine oxidation of nitrogenous compounds (sweat, urine, etc). Algae does not, in general, cause a huge amount of CC's unless you have horribly green pool.
 
ok, i'm going to trust u and not waste time with another overnight. I'm going to begin SLAM process now. before I started interestingly noticed pH rose from 7.2 to 7.6 in one day and TA went down from 90 to 70 in one day. I ran the bubbler for an hour or so and kids and i swam twice, for 1/2 hr each. currently:

FC= 6
CC= .5
pH=7.6
TA=70
81 degrees
CSI =.08
added 61 oz MA to get pH down to 7.0. started to aerator to raise it but I figured it's not going to be a good idea since I can't get an accurate reading while SLAMing so i'll shut it off.

off I go to add 405 oz of chlorine?! thx@!
 
Yep, don't bother measuring pH or anything else. Just measure FC/CC to make sure you're reaching your target values. Also, leave your pump running to keep the water moving and run whatever water features you have to make sure they are seeing chlorinated water as well. No need to run them 24x7 but just do it daily for an hour or so to keep the lines flushed with water.
 
Yep, don't bother measuring pH or anything else. Just measure FC/CC to make sure you're reaching your target values. Also, leave your pump running to keep the water moving and run whatever water features you have to make sure they are seeing chlorinated water as well. No need to run them 24x7 but just do it daily for an hour or so to keep the lines flushed with water.


Either I'm getting inaccurate FC #s depending on if I measure at night/day... or I don't know what.

last night @ 6:30pm I dumped in 3 gallons of chlorine. that would have been a bit under 28 oz which I knew wasn't hitting the shock # for my supposed CYA but I honestly think I probably have less CYA than 70 so I went with 3 gallons since I read too much chlorine can be bad on the pipes and I was off to work.

at 10:30pm I measured FC at 23 and did a good brushing.
This morning, as far as I could tell, before direct light hit the pool at 6:30am I measure FC at 19.5. If it only at 2 FCs the night before and now ate 4.5 it either has to do with algae that came out of the bubble or i'm measure wrong or something.

I'll run bubbler now and recheck FC. I'll read SLAM directions again but I didn't see how often to add more chlorine. I know part of it is adding a lot at once-maybe in the beginning only (?). how low can it drop before i need to add more...

sorry, i never seem to have a short simple reply!

thx!
 
.... so I went with 3 gallons since I read too much chlorine can be bad on the pipes ....

Well, you certainly never read that here .... you have to understand that there is a tremendous amount of B.S. printed online about pool care every single day. Just this morning I was reading an article in a highly trafficked news aggregator (the name rhymes with "Bapple News"). The article stated that, in order to clean up a hurricane Irma-affected green swamp pool, you have to make sure you get that chlorine reading all the way up to 8ppm because that's "super shock" level and, by golly, don't even think about swimming in it because it'll melt your eyeballs out.

If the TFP potty-mouth filter would let me write it, I would scream - B _ L L S H _ _ !!!!!!!!

So, what you need to do is forget about everything you've "heard" and all the garbage that is printed out there about pool care and trust that TFP has tens of thousands of visitors/users who have successfully completed a SLAM and restored their garbage-green, pool-store-ruined, PITA pools back to crystal clear.

Bottom line - your pool has an algae problem and the only way to fix it is with a SLAM. If your CYA is 70ppm, and let's just assume it is, then your shock level of FC is 28ppm. FULL STOP! No sorta, no kinda, no maybe I should back off a bit on the FC...28ppm FC, period! You dose the pool to that level and you do you very best to maintain that (we realize you have a life and need to go to work, etc, etc). It might require measuring early in the AM and then dosing it and then trying to get back at lunch time to measure & dose again or just making sure you get it in the morning and the evening, but maintaining the shock level FC is what kills everything and it will do absolutely no harm to you, or your pool, or you pool equipment.

I can walk you through the detailed chemistry of how and why CYA buffers chlorine OR you can simply trust the experience of the tens of thousands of pool owners before you. But I can say with absolute assurance that half-measures will only lead to lousy results.

Based on the info provided, you need to keep the SLAM up. You have three criteria to achieve before you stop the SLAM -

1. CC's are less than 0.5;
2. OCLT < 1ppm;
3. Crystal clear water with no algae visible anywhere, at all.

On criteria #3, if you can flip a quarter into your deep end and clearly make out heads or tails, then the water is crystal clear.
 
Reading FC of 24 now. I also just got a bunch of lantana flowers in pool from pruning so i'll scoop that up. off to add another 8.4.

thx for the offer of the CYA/chlorine explanation. I've read it here. my brain only goes so far when it comes to chemistry so if u can do it in a couple sentences that'd be great, otherwise I've chosen to trust this method and appreciate all your help.

Regarding the metal corrosion, on the "defeating algae" page, if it wasn't for that, it'd be way easier to just pour in extra chlorine and not have to keep monitoring throughout the day
 
outdoorsgal - hello! It's nice to meet you! Thanks for being a lifetime supporter! I have family I help with their AZ pool and their story has some similarities to yours! Neat right? They had a SWG that was ready for replacement but they have a nice pool store with liquid bleach and wanted to give it a try for a change to see how the rest of us lived.

The first thing they asked me about was the number of gallons of bleach they had to put in each day seeming like a lot. Totally understandable! I showed them the math at how their SWG was "making" that much bleach each day, so they really weren't adding any more than their SWG did already, which they never had any problems with. I explained that these TFP levels are well researched and well supported and that since the era of CYA stabilization began, we're able to maintain these FC levels to help keep our pools safe as can be. One is an engineer and the other a psychologist, so there was a discussion I'll spare you of, but rest assured, three hours later, I had two new TFP followers that were eager to give us a try!

So, let me say, I'm really proud of you for researching the chemicals you're using! MA scared the living daylights out of me the first time I read the label, but then I did research limited to its use in pool PH management only and felt a lot better (as opposed to its scarier uses in acid washing, concrete etching, and other full strength fumes and spraying and splashing horror). When used correctly for PH in pools, it really can be a super safe and awesomely cheap option! I love that it doesn't add the nasty stuff that dry acids add, right?

I was absolutely shocked when I learned that pool chlorine was bleach. I mean I was horrified. I'm swimming in bleach! What??!! LOL! Then I learned that we're really not swimming in bleach - far from it. We're swimming in a few parts per million of bleach. Hilarious! Like between 4 and 24 parts in 1,000,000 depending on your CYA level. Most tap water, that we consider super safe for drinking gallons of each day, has 0.2 PPM to 3 PPM bleach in it. We don't even drink pool water! So all things considered, I feel really great about using bleach now. I don't drink pool water, but swimming in it makes me feel really safe from all the bacteria and algae and nasty organisms that would love to take over my swimming hole if I didn't properly chlorinate it for my CYA level.

I'm sorry you're having this scare with potential black algae. My Florida pool had a massive BA infestation after years of being pool stored and my CYA being way over 200. It took a long time to fix. I urge everyone to maintain target FC per cya at all times to avoid having this ridiculous problem. In my mind, playing with the min level is not worth it. Target is easy enough to maintain. Also important to note that PH must be in range for bleach to work right, and pump must circulate enough.

Sorry for the long post, but I just want you to know, these people in your thread really know what they're talking about. Even if you find things on other websites or news articles that say different things, please ask about them before acting on them. If you really trust TFP and do everything it says, skipping none, then things like BA can't happen without really special exceptions. The levels of bleach advocated here (always per your current cya) are safe for decades on properly plumbed pools and properly finished pools. I doubt there is another site/system that is better for maximizing the life of a finish or liner or equipment. I doubt there is a system that has better research backing up it's chemistry/balance/ph/chlorination levels to balance safety for swimmers and longevity of investments. The recommended chemicals are all industry accepted and well proven.

Please know that if you TRUST the TFP system and its experts, you're putting your faith in a great place. If you try to mix it with other advice, you're making things worse, not better. You're clearly very smart, but once you get the recipe perfect, just follow it and apply your intelligence to some other problem that really needs it instead of stressing yourself out over it. Again, I applaud your safety and caution, but I'd suggest you to review the evidence TFP has amassed and based its science on instead of random things from across the net. Context and relevance matter entirely. I hope I helped. Best wishes!
 
Matt, I did read this here. Pool School - SLAM - Shock Level And Maintain (under "defeating algae" paragraph 5):

"If you don't have any idea of your CYA level, you risk either not using enough chlorine, and failing to get rid of the algae, or using too much chlorine, and causing metal corrosion.."

Yes. But you do have an idea of your CYA. It’s somewhere in the neighborhood of 60-70ppm.

The fact of the matter is that warning is a bit conservative in nature and not one I totally agree with (but it’s written to cover the bases). If you have any measurable level of CYA in the water (ie, CYA > 30ppm), then the amount of active chlorine (hypochlorous acid and hypochlorite anion) is so low that it will not significantly affect your equipment unless you had excessive FC levels (> 100ppm). So, since you’ve measured you CYA and know that it’s around 60-70ppm, then you can dose chlorine to shock levels.

If you want, go measure your CYA again. The elevated FC you have right now won’t affect the CYA test.
 

Enjoying this content?

Support TFP with a donation.

Give Support
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.