The bigger point might be that you lost 4 something fc in two days not counting any that may have been generated by your swg. It appears you didn't test yesterday. While you're trying to dial in your swg, you should be testing every day. You should never let your FC go below the minimum even as your water gets colder.
chlorine 'stuggles'
- Thread starter eqbob
- Start date
Yep. I screwed up. I torqued my back pretty bad in the gym yesterday and wasn't in a position to bend and test much so I didn't get testing done. My intention is certainly to never let FC go below minimum...just made a mistake in how low I turned the cell and then couldn't follow up on the testing. With the equivalence in pool math being able to be calculated, I think I can dial it in much closer over the next few days. I am at minimum now and will be adding some bleach in to get it kicked up a bit in about an hour.
The other rookie mistake I made was forgetting to adjust pool math for 12000 instead of 10000 gallons. I had it in there that way, but pool math keeps freezing on safari on iPad so when I cleard cache to cover the browser I forgot to reset.
It's exactly the same because the SWG output ratings are in ppm Cl2 chlorine gas equivalent. So yes, you saw less being added because of chlorine consumption/usage. If you ran the SWG overnight or if you used an opaque pool cover, then you'd see the rise be closer to what you expect though there is still chlorine loss even without sunlight due to chlorine reacting with whatever it can find (including a pool cover itself).
I plan on testing tonight as soon as pumps stop...to,or row morning befo they start and tomorrow night when they stop. Knowing output of cell and those three points ought to give me a good general idea of consumption across 24 hours. I can then zero in the cell setting much better than the high low high low approach I've been doing.
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Thank you Richard!
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Thank you Richard!
8.2 last night, 7.4 this morning so 0.8 loss overnight.
I assume each pool is different in terms of its overnight loss.
I assume each pool is different in terms of its overnight loss.
Are you testing with 25 ml sample. If so, there is no reason to. .5 increments can be done with a 10ml sample.
If he is trying to calculate an accurate loss rate, then it's OK to use a 25 ml sample size. He's not doing an OCLT with its rough criteria, but rather is trying to figure out the pool's chlorine usage so he can set the SWG accordingly.
If there was no sun on the pool overnight, then 0.8 ppm loss is higher than I'd expect to see. You might have some nascent algae growth left over from when the FC went too low or you may have a dirty filter or pollen or something in the water being oxidized by the chlorine. Or perhaps with the pump off the chlorine got used up locally or outgassed from the surface of the pool if you didn't take your water sample deep enough. Though you're technically within the OCLT criteria, it's still a higher loss than usual. You could try this again to confirm and make sure you start running the pump again before each test to mix the water.
If there was no sun on the pool overnight, then 0.8 ppm loss is higher than I'd expect to see. You might have some nascent algae growth left over from when the FC went too low or you may have a dirty filter or pollen or something in the water being oxidized by the chlorine. Or perhaps with the pump off the chlorine got used up locally or outgassed from the surface of the pool if you didn't take your water sample deep enough. Though you're technically within the OCLT criteria, it's still a higher loss than usual. You could try this again to confirm and make sure you start running the pump again before each test to mix the water.
I went 25ml and 0.2 per drop for increased accuracy during this "figuring things out" time.
I did test for CC each time and both were 0.
Richard--the sun came up this morning at 6:48, so there was about an hour of sun on the pool before I got the test in this morning.
How deep are you supposed to take a sample? I've been dipping it in over the top of the tube and letting water flow in, so it's certainly "surface" water. Don't recall seeing that level of direction in pool school. Also did not know to turn the pump on to mix water before each test. Pumps start at 8am.
I can always backwash the filter...haven't done that for a little bit...filter pressure hasn't strayed off of 9 psi.
There was some stuff in one of the skimmers yesterday morning. Stuff being a dead frog and a dead bird. Have no idea how the bird got in there!?! Wasn't there Friday, so happened Saturday.
I did test for CC each time and both were 0.
Richard--the sun came up this morning at 6:48, so there was about an hour of sun on the pool before I got the test in this morning.
How deep are you supposed to take a sample? I've been dipping it in over the top of the tube and letting water flow in, so it's certainly "surface" water. Don't recall seeing that level of direction in pool school. Also did not know to turn the pump on to mix water before each test. Pumps start at 8am.
I can always backwash the filter...haven't done that for a little bit...filter pressure hasn't strayed off of 9 psi.
There was some stuff in one of the skimmers yesterday morning. Stuff being a dead frog and a dead bird. Have no idea how the bird got in there!?! Wasn't there Friday, so happened Saturday.
Backwash completed. Already pitch black. Will test in approx 1h30m when pump cycle is nearly complete.
All numbers in PPM
Last night: 8.2
This morning: 7.4
Overnight Loss 0.8
This Evening: 7.4
Net Day Loss 0.0
SWG cell output: 1.3 (IC40 at 12 hours run time at 20%)
Total Day Loss: 1.3
Total 24 Hr. Loss: 2.1 (0.8+1.3)
(In reality, probably a little bit less than that, as the pump was off during backwashing, and I tested before the end of the run cycle, so probably about 11 hours total production instead of 12, which would knock 0.09 off, but none of this stuff appears to be *that* exact, so we'll just call it 2.1)
For 12,000 gallons, IC40 at 12 hours @ 30% makes 2.0ppm, 35% makes 2.3 ppm, so set to 35% to stay ahead of estimated daily loss.
In reality, could set it at 30% and with a deficit of 0.1 per day, bring FC down to upper target of 6 in ~2 week timespan. But...again, since none of this seems that exact, so I think I'll go with the overage. Plus, if overnight loss is higher, as Richard said, due to fighting some left-behind stuff when FC got too low for 36-48 hours, the extra will help it along.
Anyone care to weigh in the results and the plan?
FYI, CC at all test times was 0.
Last night: 8.2
This morning: 7.4
Overnight Loss 0.8
This Evening: 7.4
Net Day Loss 0.0
SWG cell output: 1.3 (IC40 at 12 hours run time at 20%)
Total Day Loss: 1.3
Total 24 Hr. Loss: 2.1 (0.8+1.3)
(In reality, probably a little bit less than that, as the pump was off during backwashing, and I tested before the end of the run cycle, so probably about 11 hours total production instead of 12, which would knock 0.09 off, but none of this stuff appears to be *that* exact, so we'll just call it 2.1)
For 12,000 gallons, IC40 at 12 hours @ 30% makes 2.0ppm, 35% makes 2.3 ppm, so set to 35% to stay ahead of estimated daily loss.
In reality, could set it at 30% and with a deficit of 0.1 per day, bring FC down to upper target of 6 in ~2 week timespan. But...again, since none of this seems that exact, so I think I'll go with the overage. Plus, if overnight loss is higher, as Richard said, due to fighting some left-behind stuff when FC got too low for 36-48 hours, the extra will help it along.
Anyone care to weigh in the results and the plan?
FYI, CC at all test times was 0.
Yeah, you probably weren't measuring accurately overnight given your zero loss during the day. Odds are the morning reading wasn't as low as you measured. Perhaps it was 7.8 or 8.0 which would make more sense.
You should generally take your water sample a foot or so below the surface and should ideally run the pump before taking a sample though if you measure deeper that might be OK. Very still water doesn't mix well since diffusion is very slow so chlorine outgassing and the greater loss from sunlight closer to the surface mean that unmixed water near the surface will measure lower in chlorine until you start mixing up the water.
You should generally take your water sample a foot or so below the surface and should ideally run the pump before taking a sample though if you measure deeper that might be OK. Very still water doesn't mix well since diffusion is very slow so chlorine outgassing and the greater loss from sunlight closer to the surface mean that unmixed water near the surface will measure lower in chlorine until you start mixing up the water.
- May 22, 2013
- 2,796
- Pool Size
- 12000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
The new twist at Walmart is "Easy Pour". I think that's the replacement for "Splash-less" since you really can't make something totally Splash-less they may have figured it's better for liability to go with Easy Pour. Already had someone post about having a foaming problem in his spa and turns out he had Walmart "Easy Pour".
As always if it says "Concentrated" it's OK to use just means they put in less water so it's a little stronger in percent of chlorine and in a smaller bottle.
Wife was at the grocery store at the time of deciding the need and it was easy enough to pick up 2 bottles of regular 'ol Chrlorox 8.25% at the time. Convenient and can always use it in the laundry if needed <G>.
Certainly possible. The science behind the test is "confusing" to me with the two scoops deal. Since those are very small scoops and therefore hard to replicate to any exact degree on a consistent basis, and it all goes into solution, it going to be highly variable how much "pink" you have. If it all goes into solution, one would think that it would take more of the reagent to react. The tests could therefore be off depending on how much you're off on the powder input? I guess the test would be to use one scoop and do the test, then 2 scoops, and do the test, and then 2 heaping scoops and see if all three numbers come out the same.
Of course, my reasoning could be all wet also....
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That could definitely have affected this morning's sample, as I took it at the steps and just used the still water at the edge which is only 6 inches or so deep. Normally, that wouldn't matter because there is a return one step below it, so the water gets mixed well there (presumption on my part), but the pump wasn't on when I took the sample this morning and so that water had sat there for nearly 12 hours...including an hour of early sunlight.
I am a bit confused. You are trying to do an OCLT, right? If so, your swcg should be off and your pump on.
No. I admit it seems similar, but I'm looking to determine a 24 hour FC loss, so I can dial in the appropriate salt cell usage (% on time) for winter operations.
For the fun of it I tested overnight loss this morning, taking deeper water and saw 0 loss. The water remained at 7.4 ppm using the 25 ml sample and .2 drop equivalencies. Did it twice and got the same result. CC remains 0.
Thanks. ChemGeek was right, I probably am now overestimating the daily loss because of factoring in the 0.8 from taking shallow still water right at the step. So probably right now, the salt cell is working a little harder than it has too with me setting it at 35%. So I will have to watch and adjust, but at least now I have a process that I can use and I know exactly what the SWG is doing and those impacts.
By the end of the day the temp here will be low 40's, so we'll see what that does to water temp. May be adding in bleach pretty quick <G>.
By the end of the day the temp here will be low 40's, so we'll see what that does to water temp. May be adding in bleach pretty quick <G>.
For sampling, I've always used a 5 foot length of 0.5" ID PVC pipe to dip into deeper water and draw out a sample from below the surface. A nice way to do it without getting your arm wet (and cold) as long as you can briefly hold the water in the pipe with your thumb or rig up a valve on one end of the pipe.