Frustrating slamming process!

[doncaruana]

I replaced my liner this year and I've been chasing getting it clean all year. I've entertained a fair amount and don't like to have massive chlorine when doing so which has put a damper in getting ahead of this.

I know I have something and it won't die! But here's where I am...

My CYA is only about 30. Yes, this is low and lower than I would normally keep it. But I'd have to double my chlorine if I raised it up and I figure it *should* be easier to finish SLAMing this with it lower. Is that a bad assumption? And, yes, I know that means I lose a lot more during the day. But I've still been able to keep it above 12 during this process.

But here's where my true confusion comes in...3 nights ago, I lost 1ppm overnight and had 0.5 CC. Then 2 nights ago, I lost 2 (and dropped to 10 but had only .5cc). I immediately raised the FC up again in the morning when I tested it was low. Then last night, I lost 2 more but had no CC. What i don't understand is why such a low amount of combined chlorine with such high loss of free chlorine? I never have more than .5 cc and frequently 0.

So, yes, I'm going to keep hammering this thing, but was just wondering about the cya and the lack of combined chlorine.

 

[Donldson]

What i don't understand is why such a low amount of combined chlorine with such high loss of free chlorine?

These two things are unrelated. CC comes from chlorine oxidizing ammonia compounds, killing algae usually does not create it.

 

[Newdude]

How did your CYA get to 30 ? Was it always low for a SWG, or did you drain in anticipation of the SLAM ? I ask because this is the hairy part of the season for daily FC loss, even in Michigan. If the CYA has been low all season, you likely spent a good deal of time, or certain times of the day dancing the minimum line, leading to the current issues with clarity.

Don't worry about 'massive amounts of chlorine' with guests over. It's indistinguishable between minimum and SLAM per your CYA level. If your pool smells like chlorine with guests over, it's the guests fault and it will smell the same with a FC of 5 or a FC of 12.

The difference is, if your bather load eats up a couple ppm FC, you have more to spare with the higher start point and will remain sanitary.

 

[doncaruana]

How did your CYA get to 30 ? Was it always low for a SWG, or did you drain in anticipation of the SLAM ? I ask because this is the hairy part of the season for daily FC loss, even in Michigan. If the CYA has been low all season, you likely spent a good deal of time, or certain times of the day dancing the minimum line, leading to the current issues with clarity.

Don't worry about 'massive amounts of chlorine' with guests over. It's indistinguishable between minimum and SLAM per your CYA level. If your pool smells like chlorine with guests over, it's the guests fault and it will smell the same with a FC of 5 or a FC of 12.

The difference is, if your bather load eats up a couple ppm FC, you have more to spare with the higher start point and will remain sanitary.

I had to replace all the water because of the liner replacement. So I raised it to 30. I haven't taken it higher. Oh and btw, my water has only dipped from crystal clear for about one day this year. Which is also part of the overall frustration

 

[Newdude]

my water has only dipped from crystal clear for about one day this year

OK, so you have that going for ya. But overnight FC loss with no UV means something is brewing. You're likely keeping it at bay with the SWG, but it's there.

So you have two choices. Either you're not hitting the SLAM frequent enough with testing/adding, so it's taking its sweet time, or it's hiding in plain sight and being reintroduced during the process. Ladder rails, light niches, autofills, all up in the skimmers, etc. Go on a full blown algae hunt either way because every last inch is suspect until proven otherwise.

Brushing is huge as well. Algae grows a protective film to enable it to grow in harsh environments. Each pass of the brush removes a layer and the next layer of algae is killed. It may be many layers deep and take many brushing to get it all.

 

[IceShadow]

Failing OCLT in a clear pool during a SLAM usually means hidden algae - definitely look and scrub out those places Newdude just mentioned

 

[jeffchap]

After completing a SLAM earlier this year to open my pool, my FC was 32 and my CYA was 80. Now I maintain FC at 7 with CYA still at 80.

The water was indistinguishable. No smell, harshness, dry skin or faded suits either time. I fear your goal of maintaining low FC is causing you needless trouble.

Get that CYA and FC up to the target ranges for a saltwater pool and give yourself some margin of safety. I promise, you won't notice any difference.

 

[IceShadow]

Keeping your CYA at 30 until the SLAM is passed is smart, by the way. You can bump up to 70 or so once you are 100% sure there's nothing still growing. So that's a good thing to do and not something to stress on.

 

[doncaruana]

I forgot to mention my alkalinity is high too which also keeps pulling my ph up which of course lowers the effectiveness of the chlorine. Bringing TA down is a slow process too.

I also like to run my dolphin here and there too (which would help with the scrubbing part) but I also don't want to put it in at 20ppm chlorine (they say not to have over 4 I think) even if it's only for a couple of hours.

So later today I will scrub it by hand and put more acid in to continue working on that TA. Always a process...

 

[IceShadow]

Keep in mind that the FC test in the Taylor kits won't be accurate when FC is over 10.

Generally speaking you can ignore TA / FC after the adjustment down to 7.2 at the start of the SLAM until the SLAM is complete.

The requirements/recommendation on pool equipment doesn't take the FC/CYA relationship into account. FC of 12 with CYA of 30 is much less harsh than FC of 3 with CYA of 0. I leave my Dolphin in the pool the entire season when people aren't actively swimming and my FC is always in the 5-11 range.

 

[Newdude]

What is the TA ?

 

[mknauss]

ph up which of course lowers the effectiveness of the chlorine.

Only if there is 0 CYA in the water. Any amount of CYA in the water negates the pH effect on chlorine effectiveness.

 

[doncaruana]

Keep in mind that the FC test in the Taylor kits won't be accurate when FC is over 10.

Generally speaking you can ignore TA / FC after the adjustment down to 7.2 at the start of the SLAM until the SLAM is complete.

The requirements/recommendation on pool equipment doesn't take the FC/CYA relationship into account. FC of 12 with CYA of 30 is much less harsh than FC of 3 with CYA of 0. I leave my Dolphin in the pool the entire season when people aren't actively swimming and my FC is always in the 5-11 range.

I use tf test kits. Always have.

Didn't realize about the harshness.

Only if there is 0 CYA in the water. Any amount of CYA in the water negates the pH effect on chlorine effectiveness.

This I ALSO did not know! I swear I've read through everything on this board at least once!!

 

[mknauss]

This I ALSO did not know! I swear I've read through everything on this board at least once!!

Pool Water Chemistry

This thread presents my findings so far on pool water chemistry including the following: More Accurate Calcite Saturation Index (CSI) to replace Langelier Saturation Index (LSI) Calculation of ppm HOCl (disinfecting chlorine) at various levels of Total Free Chlorine (FC) and Cyanuric Acid (CYA)...

www.troublefreepool.com

 

[doncaruana]

Pool Water Chemistry

This thread presents my findings so far on pool water chemistry including the following: More Accurate Calcite Saturation Index (CSI) to replace Langelier Saturation Index (LSI) Calculation of ppm HOCl (disinfecting chlorine) at various levels of Total Free Chlorine (FC) and Cyanuric Acid (CYA)...

www.troublefreepool.com

OK - let me rephrase that then...I didn't *remember*! But I HAVE read everything I can here. There's just SO much awesome info!! Particularly from Chem Geek...I'm a fellow geek, just not a chem one!

 

[doncaruana]

OK...so now I'm SUPER frustrated... Let me start by saying I have been using the tftests for a lot of years, rather successfully, so, as the expression goes, this isn't my first rodeo. But...

Last night I turn off the chlorinator and run the pump for a while after the sun has gone to where there's no direct sunlight on the pool anymore (just shy of 9pm here). I tested my water and I get 17ppm. I decide to test it again (I had plenty of sample water) and this time I got 17.5ppm. OK - no big deal. Maybe I had a few extra big drops for whatever reason.

This morning I wake up and run the pump for a bit, again with the chlorinator off and grab a sample. My first test, I get 15.5! WTH?? I'm going backwards! Again, plenty of sample water, so I clean everything our and test again. This time I get 18! Huh?? I've NEVER had any inconsistency like this. Clean it up and try it again...this time I got 18.5. No, I don't wipe the tip of the bottle after every drop, but I never have. I'm pretty careful about watching it though and the angle I hold the bottle, etc.

Then I decide to test my CYA again. And I basically have none. And, yes, I know, there are precious few opportunities for CYA to go away.

So I know you all must think I'm a complete loon. But I don't understand what's happening here AT ALL. Other than the obvious ("Don, you kinda suck at this if you can't get consistent results even though you're doing the same thing you always have"), does anyone have a sane explanation? Could my testing chemicals be out of whack somehow? Could the rain we got last night be affecting anything? Or have I simply gotten incredible stupid about these performing these tests (this is an okay answer, even though I don't like it). I am completely flummoxed...

 

[Newdude]

Thanks for the testing backstory. We see so many part time-ers that only test if somethings off. So it's fair of everyone to ask you if you're doing it right.

All I have for you is that I've seen so many folks mess up the morning test for whatever reason. Too much coffee with a shaky hand....... not enough coffee.... I dunno. But there is definitely some unavoidable human error in repeating 36 perfect drops. (Etc). The Speedstir is worth its weight in gold here and you STILL might be off.

I've flubbed my own more times than I can count and the only thing you can do is take a deep breath and slow it down. I know. I know. It's so stupid easy, right ? But the first one surprised you and then you were anxious for the second. Again. Ask me how i know.

Clean your vial/pill good and try it again tomorrow after taking a really deep breath and a moment to clear your thoughts. Then go nice and slow.

 

[IceShadow]

How old are the reagents? Sorry if this was already addressed. >.>

 

[doncaruana]

How old are the reagents? Sorry if this was already addressed. >.>

Not so old it should be giving me that kind of issue. I'm pretty sure it's the variability of the drop sizes, tbh, which I'm not quite sure how to address. I do have new reagents on order as well as a smart stir though.

As far as update in general...for the 2nd straight night, I essentially had no chlorine loss. But I am still losing a lot during the day even with CYA in there (still only at 40).

Here's my question...is it possible that there's something about the reflectivity of my new liner or even something with all my fresh fill water that is helping burn off so much during the day? For that matter, I replaced my SWCG this year also and have this thing running at double what I do normally and I'm still barely staying ahead. Based on pool math, running my pool for 10 hours and the IC40 at 80%, that should by raising my FC by about 3.6 per day. But I'm still losing during the day (I think even if it's not terribly sunny!). I normally would run it at about 40% (which amounts to about 1.8/day) with CYA at 50-60.

For that matter, how do I actually know the IC40 is generating what it says it should? Is there a decent way to actually test this? Or am I just spinning out of control now? LOL

 

[IceShadow]

For that matter, how do I actually know the IC40 is generating what it says it should? Is there a decent way to actually test this? Or am I just spinning out of control now? LOL

Now that you know it's not losing overnight, you know that anything in the pool is dead and it won't be eating up your FC.

You can do the opposite of an OCLT now - basically test the FC level after dark, run the SWCG at 100% overnight, test FC in the morning, see how much it's gained. That'll let you know if you are producing chlorine.

If the OCLT is passing and you have no visible algae (dead or alive) and CC are 0.5 or less, then you can finish the SLAM. With a SWCG I'd recommend getting CYA up to 70. That'll help with your daytime loss, too.