Mysterious chlorine loss... SLAM even though not failing entrance criteria?

[Newdude]

Nah, Anything fresh doesn’t matter. Even the ‘dead leaves’ that were brown in the fall. They hadn’t started decomposing yet, or had decomposed enough to matter at least.

People find all kinds of dead critters from birds to frogs. My own pool was the MoleKiller9000. A lifetime of battling them and it was the first thing that worked !! They’d walk across the patio and drown.

 

[TexEdmond]

People find all kinds of dead critters from birds to frogs

I scooped a toadfrog out of my skimmer a couple days ago. It was still alive but looked a little bleached...

 

[TriangleMan]

Nah, Anything fresh doesn’t matter.

Oh go on then, keep dashing my hopes and dreams! Don't you see I'm looking for the easy way out?!

 

[TexEdmond]

 

[TriangleMan]

Just when I think I've got this licked, I get thrown for another loop. Everything was going well, SLAM proceeding for CYA=50, FC=20 for multiple days.
I passed all three criteria, including the OCLT, on Sunday morning. (FC dropped from 20.5 to 19.5 overnight).
I decided to SLAM an extra day or two for good measure, so I kept the FC at 20 all day yesterday (Sunday) as well. Brushed, vacuumed, kept the light out of the niche, etc.

I needed to fill the pool with about 500 gallons from the well because I couldn't wait on the rain any longer, but then ended up getting another ~750 gallons of rain overnight.

Well after adding the 500 gallons of fill water, I started the OCLT at FC=18.5ppm, CC=0.0. This morning, after getting the rain, FC=15ppm, CC=1.0... OCLT failed...

I've read on here that rain shouldn't affect the pool very much but after passing the OCLT, maintaining the FC, and doing very little of anything else, I have no other explanation.
I should have been able to stop SLAMMING yesterday, so this is a kick in the teeth.
It's hard to keep the faith.

 

[mknauss]

Was the pump running over night?

 

[Newdude]

We’re you mixing the whole time because of the SLAM ? A couple of % of rain water can only affect the chemistry the same % so it won’t do much if mixed properly. 2% of rain and we’ll water combined will only drop your FC from 20 to 19.6. (Or whatever the actual similar %’s were).

If the pump was off however, A couple of inches floating on the top that haven’t been mixed yet have a FC of 0. If left to disperse by itself it can either start to grow new algae, or your sample test was skewed with some non-treated water.

 

[TriangleMan]

I've had the pump on high speed 24/7.

 

[TriangleMan]

What are the odds that the well water is contaminated with a lot of organics? Hmm, that's worrisome...

(Btw, there was a dead frog in there this morning... I'm just sayin'. ;-) )

 

[TriangleMan]

Also, unrelated I think (?), where do those common swimming bugs come from?! You know the kind, they look like little black ovals with two arms (or are they legs?) that do the breaststroke all the time? Even at these elevated FC levels, I still find a handful of them in the skimmer basket...

Do they fly in? What are those things and where do they come from?

 

[Bperry]

What are the odds that the well water is contaminated with a lot of organics? Hmm, that's worrisome...

(Btw, there was a dead frog in there this morning... I'm just sayin'. ;-) )

You might be fine just doing another OCLT tonight. Even if rainwater and well water brought some stuff in the chlorine should take care of it.

 

[Mdragger88]

Also, unrelated I think (?), where do those common swimming bugs come from?! You know the kind, they look like little black ovals with two arms (or are they legs?) that do the breaststroke all the time? Even at these elevated FC levels, I still find a handful of them in the skimmer basket...

Do they fly in? What are those things and where do they come from?

Possibly Backswimmers or water boatmen - they eat algae. Hopefully if u eradicate the algae they will leave since their food source will be gone

 

[TriangleMan]

Should I be worried about the conduit that brings power to the underwater light from the electrical switch? If that's ~65ft long, at ~1" diameter, then I'm looking at as much as 2.5 gallons of water (maybe 1.25 gallons, if we say the electrical cable consumes half of the available space) of zero-circulation algae breeding grounds?
Seems like a reach...

 

[mknauss]

Algae can only grow where sun can shine.

 

[TriangleMan]

Today's OCLT: Down to 20 ppm from 21.5 ppm.

I'm inclined to call that close enough.

I'm going to SLAM one more day for good measure in any case.

I think I've been introducing some error into the FAS-DPD test by not rinsing off the R-0870 scooper. I got a very strange color reaction last night that made me think the powder was messed up. (Turned light pink fairly quickly but then still took many drops to turn all the way clear). It was the difference between a starting reading of 21.5ppm and 15 ppm. It's possible I've had other artificially low FC results from contaminated powder. I've actually been afraid to rinse it for fear of introducing contaminates onto the scooper, but rinsing in reverse osmosis drinking water seems to get me more repeatable results. (Tested twice at night and in the morning). It's probably been absorbing moisture from the air.

Anyway, after $100 for the test kit and extra reagants, and $300 in chlorine in three weeks, I'm really hoping this is it.

One more day to find out.

--Exhausted in Illinois (but maybe that's more the result of the three sick kids and pregnant wife)

 

[Newdude]

I think I've been introducing some error into the FAS-DPD test by not rinsing off the R-0870 scooper

Extra powder doesn’t matter. In fact that’s the perfect way to know you used enough. Anything more than what it needs won’t dissolve so if you have one or two grains spinning around it’s perfect.

But. That brings up a great point. Slow down the test. The bottle goes completely upside down and you squeeze ever so gently to let gravity make perfect, repeatable drops fall on their own. This gets a lot of people who inadvertently squirt some big drops and lower their supposed FC. I hope that helps.

I'm inclined to call that close enough

There is either pass, or fail and allow that little bit of algae to start growing again exponentially. The end of SLAM is much easier than the beginning and far too many people quit early and end up back at square one before long.

 

[TriangleMan]

<EDIT: I'm going to move this entire post to a new thread... I think it may be worthy of a separate discussion>
< You can find that thread here: Alternative ending to SLAM >
<EDIT #2: Or not? A mod or bot merged it back into this thread... ok, I submit. See below>

As I'm continuing to SLAM and awaiting eventual good news, allow me to ponder the mysteries of the universe for a moment:

Over the past three nights, the OCLT has averaged a loss of 2ppm of chlorine per night (-1, -3.5, -1.5), over a roughly 8-hour span. Over the course of those days, the pool has consumed an average of about 20 ppm of chlorine during the day as I maintain the SLAM level.

Now it's not as if the chlorine is more active during the day, although it's probably true that the algae is, but I'd expect that the bulk of the disparity is due to the sun burning off the chlorine in my fully-sun-exposed pool over the course of 16 sunlit hours, especially given that the FC is at 40% of CYA, which likely leaves a large portion of it "unprotected" by the cyanuric acid. (I cringe every time I dump two gallons of chlorine into the pool between the hours of 11am and 2pm).

So here's my thought:
At this point at the tail end of the SLAM, I don't mind if it takes a little longer, since the pool is perfectly crystal clear anyway, so what if I focused the effort on high FC levels during the nighttime to reduce the algae and only enough during the day to keep the algae level stable rather than increasing? I've seen it stated in the forum multiple times that just adding 5ppm during the day is enough to get by and prevent algae from growing while people await test kits... so why not also while awaiting more efficient nighttime sanitizing?

In other words, if I kept FC at SLAM levels during the night, and at FC/CYA maintenance levels during the day, that would save (1) a lot of money on chlorine sacrificed to the sun, (2) a lot of trouble trying to keep up with SLAM levels during the day when I need to focus on my actual day job, and (3) a lot of frustration from SLAMmers who aren't seeing the return on investment for the seemingly marginal gains.

Again, this may only be relevant at the end of the SLAM where the OCLT is oh-so-close compared to the massive amount of daylight chlorine loss, and it would be of utmost importance to know the level at which the algae would be kept in check during the day without allowing it to multiply.

Thoughts?

 

[TriangleMan]

I've seen a lot of frustration with SLAMs that drag on for weeks, including in my own experience. As a result, my mind has wandered into dangerous territory... Allow me to ponder the mysteries of the universe while I continue awaiting the eventual success of my own SLAM:

Over the past three nights, the OCLT has averaged a loss of 2ppm of chlorine per night (-1, -3.5, -1.5), over a roughly 8-hour span. Over the course of those days, the pool has consumed an average of about 20 ppm of chlorine during the day as I maintain the SLAM level.

Now it's not as if the chlorine is more active during the day, although it's probably true that the algae is, but I'd expect that the bulk of the disparity is due to the sun burning off the chlorine in my fully-sun-exposed pool over the course of 16 sunlit hours, especially given that the FC is at 40% of CYA, which likely leaves a large portion of it "unprotected" by the cyanuric acid. (I cringe every time I dump two gallons of chlorine into the pool between the hours of 11am and 2pm).

So here's my thought:
At this point at the tail end of the SLAM, I don't mind if it takes a little longer, since the pool is perfectly crystal clear anyway, so what if I focused the effort on high FC levels during the nighttime to reduce the algae and only enough during the day to keep the algae level stable rather than increasing? I've seen it stated in the forum multiple times that just adding 5ppm during the day is enough to get by and prevent algae from growing while people await test kits... so why not also while awaiting more efficient nighttime sanitizing?

In other words, if I kept FC at SLAM levels during the night, and at FC/CYA maintenance levels during the day, that would save (1) a lot of money on chlorine sacrificed to the sun, (2) a lot of trouble trying to keep up with SLAM levels during the day when I need to focus on my actual day job, and (3) a lot of frustration from SLAMmers who aren't seeing the return on investment for the seemingly marginal gains.

Again, this may only be relevant at the end of the SLAM where the OCLT is oh-so-close compared to the massive amount of daylight chlorine loss, and it would be of utmost importance to know the level at which the algae would be kept in check during the day without allowing it to multiply.

Thoughts?

 

[TriangleMan]

So here's my thought:
At this point at the tail end of the SLAM, I don't mind if it takes a little longer, since the pool is perfectly crystal clear anyway, so what if I focused the effort on high FC levels during the nighttime to reduce the algae and only enough during the day to keep the algae level stable rather than increasing? I've seen it stated in the forum multiple times that just adding 5ppm during the day is enough to get by and prevent algae from growing while people await test kits... so why not also while awaiting more efficient nighttime sanitizing?

In other words, if I kept FC at SLAM levels during the night, and at FC/CYA maintenance levels during the day, that would save (1) a lot of money on chlorine sacrificed to the sun, (2) a lot of trouble trying to keep up with SLAM levels during the day when I need to focus on my actual day job, and (3) a lot of frustration from SLAMmers who aren't seeing the return on investment for the seemingly marginal gains.

Again, this may only be relevant at the end of the SLAM where the OCLT is oh-so-close compared to the massive amount of daylight chlorine loss, and it would be of utmost importance to know the level at which the algae would be kept in check during the day without allowing it to multiply.

So I see that there's a very similar (and somewhat contentious!) thread here:

SLAM Criteria Disagreement

Well, you know where it's going: 1) if you have a larger pool, SLAM chlorine gets expensive. 2) 2021: many (most all in my area) stores are sold out of 'pool chlorine' (liquid & tablets!). As you can see in the threads, we are regularly going ~10 days, just waiting for the water to clear...

www.troublefreepool.com

I don't mean to rehash that argument. I would make a distinction between my case and his that the pool is crystal clear at this point, and the user is willing to trade speed for efficiency and cost. (In my world, there's always an iron triangle between Performance, Cost, and Schedule... you get to pick 2. I'm asking to pick performance and cost at the expense of schedule, as long as we can reasonably guarantee the performance piece.) [The current TFP approach may be able to be described as Performance (get it done!) and Schedule (as quickly as safely achievable, with lower chance of recurrence) at the expense of whatever cost?]
Nevertheless, if this is not worth engaging at this point, feel free to ignore it. I'm not trying to start a war with TFP.

 

[Bperry]

So I see that there's a very similar (and somewhat contentious!) thread here:

SLAM Criteria Disagreement

Well, you know where it's going: 1) if you have a larger pool, SLAM chlorine gets expensive. 2) 2021: many (most all in my area) stores are sold out of 'pool chlorine' (liquid & tablets!). As you can see in the threads, we are regularly going ~10 days, just waiting for the water to clear...

www.troublefreepool.com

I don't mean to rehash that argument. I would make a distinction between my case and his that the pool is crystal clear at this point, and the user is willing to trade speed for efficiency and cost. (In my world, there's always an iron triangle between Performance, Cost, and Schedule... you get to pick 2. I'm asking to pick performance and cost at the expense of schedule, as long as we can reasonably guarantee the performance piece.) [The current TFP approach may be able to be described as Performance (get it done!) and Schedule (as quickly as safely achievable, with lower chance of recurrence) at the expense of whatever cost?]
Nevertheless, if this is not worth engaging at this point, feel free to ignore it. I'm not trying to start a war with TFP.

I think most people try and top up the chlorine 3-4 times per day. Of course more is better. I’m not sure the amount of chlorine is any different in the end, but would be interested to hear if so.