- Jul 21, 2013
- 53,029
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
@Leebo make note of some very slick graphic presentations.
Fresh fill - cloudy water?
- Thread starter TheCatLady
- Start date
Also notable from the graphs - bound can be considered a "reserve" as well as buffer. It's a great representation of why to use CYA, and why the chlorine in the water isn't perceived as harsh by most people.
I have to say it truly helped me understand the relationship between the two and why a higher level of FCl with CYA is less harsh than even 1ppm FCl with no CYA.
This also really got me wondering about ORP. Now, I don't know chemistry and wrapping my head around reactions is quite difficult since I don't have a solid base. But does ORP measure Active chlorine as in HOCl?
My Wellis monitor measured over range the first time when I raised my Fcl to 10 (with very low CYA), but it's been staying under 750mv constantly since then, with minor ph fluctuations, even when I raised FCl to 12 (with 30 CYA). I thought it's just inaccurate, but now in light of the new info I have it might just be measuring active chlorine, which would make sense.
Edit: well, turns out that the short answer is yes. The long answer (different monitor, same principle): Free chlorine, total chlorine, and ORP? Understand the differences. | iopool Help Center
This also really got me wondering about ORP. Now, I don't know chemistry and wrapping my head around reactions is quite difficult since I don't have a solid base. But does ORP measure Active chlorine as in HOCl?
My Wellis monitor measured over range the first time when I raised my Fcl to 10 (with very low CYA), but it's been staying under 750mv constantly since then, with minor ph fluctuations, even when I raised FCl to 12 (with 30 CYA). I thought it's just inaccurate, but now in light of the new info I have it might just be measuring active chlorine, which would make sense.
Edit: well, turns out that the short answer is yes. The long answer (different monitor, same principle): Free chlorine, total chlorine, and ORP? Understand the differences. | iopool Help Center
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There was a discussion some months ago about ORP probe measurement accuracy that, well, was way over my head but the conclusions were within grasp. Since I don't use electronic monitoring I have no capacity for recall on it, but in case you are not using it, I will point out the search block on top of the threads. There's an advanced option once you click in it that I've found to be handy for expounding on a subject using the great many threads here.
I believe there were many of our "heavy-hitters" involved in that thread, but I'm guessing a search will turn up several threads. You probably want the most recent
to find "that" one.Boy, did I go down a rabbit hole there 
I've found quite a few different threads on the topic, most of them dealing with ORP controllers.
It is a lot clearer now what ORP measures and its relation to FCl and Ph. I understand that ORP sensors are not very reliable and difficult to use as controllers.
However, mine does not control anything. It's simply there to broadly monitor the water parameters and for me to get an idea when I should get my testing kit out. It should be reliable enough for this purpose, especially since I do not add other chemicals (like msp) that would affect the ORP readings besides HOCl.
I've found quite a few different threads on the topic, most of them dealing with ORP controllers.
It is a lot clearer now what ORP measures and its relation to FCl and Ph. I understand that ORP sensors are not very reliable and difficult to use as controllers.
However, mine does not control anything. It's simply there to broadly monitor the water parameters and for me to get an idea when I should get my testing kit out. It should be reliable enough for this purpose, especially since I do not add other chemicals (like msp) that would affect the ORP readings besides HOCl.
- Jun 1, 2018
- 13,811
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
The more cya you have in the water the more the orp will be affected & skewed. It kinda convolutes things - @JoyfulNoise can elaborate furtherBoy, did I go down a rabbit hole there
I've found quite a few different threads on the topic, most of them dealing with ORP controllers.
It is a lot clearer now what ORP measures and its relation to FCl and Ph. I understand that ORP sensors are not very reliable and difficult to use as controllers.
However, mine does not control anything. It's simply there to broadly monitor the water parameters and for me to get an idea when I should get my testing kit out. It should be reliable enough for this purpose, especially since I do not add other chemicals (like msp) that would affect the ORP readings besides HOCl.
That's true. But at 30 CYA (or 28-29, haven't measured after the last dichlor dosing) it should be reliable enough.
I don't plan on adding any more either.
On a slightly different topic, maybe a stupid question about bleach: does bleach that has been exposed to sunlight lose concentration? Let me elaborate: I have a canister of 8% bleach that I got last year. It's in a semi transparent platic container (not clear but not opaque either). It's been sitting out for half the summer but not in direct sunlight. Now when using it in the spa I find it doesn't raise FCl as much as it should, but a little less. Did it lose some of the potency due to being exposed to sunlight or was it a lower concentration than advertised to begin with?
I don't plan on adding any more either.
On a slightly different topic, maybe a stupid question about bleach: does bleach that has been exposed to sunlight lose concentration? Let me elaborate: I have a canister of 8% bleach that I got last year. It's in a semi transparent platic container (not clear but not opaque either). It's been sitting out for half the summer but not in direct sunlight. Now when using it in the spa I find it doesn't raise FCl as much as it should, but a little less. Did it lose some of the potency due to being exposed to sunlight or was it a lower concentration than advertised to begin with?
- Jul 21, 2013
- 53,029
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Bleach loses potency over time.
Breakdown of Bleach Over Time by Storage Temp - Further Reading
www.troublefreepool.com
- Jun 1, 2018
- 13,811
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Yes- you may just have salt water by now..
heat & light degrade bleach.
Yeah, that explains it then. What would be a reliable way to test the concentration of bleach so that I can do the math correctly for how much to add?
I can't measure FCl and TCl reliably over 8 so I've been adding 50% distilled water and 50% spa water to my sample. It gives me a "close enough" but not as accurate as I'd like it to be. I might have reached shock level, I might have went over it. Can't test Cc reliably either (gives me 1.5ppm), so I'll just let it drop back to normal and see if I've accomplished anything.
I can't measure FCl and TCl reliably over 8 so I've been adding 50% distilled water and 50% spa water to my sample. It gives me a "close enough" but not as accurate as I'd like it to be. I might have reached shock level, I might have went over it. Can't test Cc reliably either (gives me 1.5ppm), so I'll just let it drop back to normal and see if I've accomplished anything.
- Jun 1, 2018
- 13,811
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
When fc drops to below 8ppm add what poolmath says is 1 or 2 ppm of the bleach in question & see where it gets you 5 minutes later.
So I've been busy SLAM-ing (well, almost). More as a test run than anything because I have to drain next week to move the spa a smidge and have the heat pump installed.
Left the chlorine to drop back to normal. Measured Cc. 0.9
I mean what the...?
Either my tester is not measuring TCl accurately or my reagents have gone bad or I don't know. I have no way to reliably measure Cc while Fcl is over 8 so I know when I'm done. I mix with half distilled water but that gives me inconsistent results so I'm not gonna base anything on that.
I'd get a drop test from the US, but seems nobody ships them overseas.
Water looks great tho and no chloramine smell, so I'm not too worried, especially since I'll dump and refill next week.
Lastly, I have a question on TA. Last week, 2 days after adding borates, it measured 71.
I've since added only dichlor then bleach and dry acid. Measured TA yesterday: 82. Added 30g of acid because my ph was a bit high as well. One day later, my TA is 83. I've also added about 200ml of bleach 5% during this time, but that shouldn't have an effect on TA.
Yesterday I added another 43g dry acid which brought the TA down to 55 and Ph to 7.4
Measured this morning (have not added anything in between, only have the swg running), TA is 32?!
You can see my logs here: PoolMath Logs
What caused the TA to rise and then why did it drop so much? Even with 0 borates, 43g of dry acid should drop the TA a maximum of 16ppm.
Ps: let's assume the tester is not accurate. But I can clearly see the significant color changes after adding the reagent: from blueish green at the higher end to light green at the low end. You measure this stuff daily and you can estimate the value by the color of the solution.
Edit: turns out... Never have two similar jars when measuring. I use one for adding chemicals, and one for distilled water that I use for cleaning the stick I crush the tablets with. Turns out I picked up the wrong one which must have still had some leftover dry acid in it. I cleaned everything and remeasured and TA is at 55.
Left the chlorine to drop back to normal. Measured Cc. 0.9
I mean what the...?
Either my tester is not measuring TCl accurately or my reagents have gone bad or I don't know. I have no way to reliably measure Cc while Fcl is over 8 so I know when I'm done. I mix with half distilled water but that gives me inconsistent results so I'm not gonna base anything on that.
I'd get a drop test from the US, but seems nobody ships them overseas.
Water looks great tho and no chloramine smell, so I'm not too worried, especially since I'll dump and refill next week.
Lastly, I have a question on TA. Last week, 2 days after adding borates, it measured 71.
I've since added only dichlor then bleach and dry acid. Measured TA yesterday: 82. Added 30g of acid because my ph was a bit high as well. One day later, my TA is 83. I've also added about 200ml of bleach 5% during this time, but that shouldn't have an effect on TA.
Yesterday I added another 43g dry acid which brought the TA down to 55 and Ph to 7.4
You can see my logs here: PoolMath Logs
What caused the TA to rise and then why did it drop so much? Even with 0 borates, 43g of dry acid should drop the TA a maximum of 16ppm.
Ps: let's assume the tester is not accurate. But I can clearly see the significant color changes after adding the reagent: from blueish green at the higher end to light green at the low end. You measure this stuff daily and you can estimate the value by the color of the solution.
Edit: turns out... Never have two similar jars when measuring. I use one for adding chemicals, and one for distilled water that I use for cleaning the stick I crush the tablets with. Turns out I picked up the wrong one which must have still had some leftover dry acid in it. I cleaned everything and remeasured and TA is at 55.
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- Jun 1, 2018
- 13,811
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
For the inconsistencies I would definitely say it’s the tester- aside from your goof lol 
. But it’s what you currently have to work with so don’t take it’s very specific numbers to heart - it’s probably not that accurate. If you added any higher ta fill water your ta will increase.
www.troublefreepool.com
. But it’s what you currently have to work with so don’t take it’s very specific numbers to heart - it’s probably not that accurate. If you added any higher ta fill water your ta will increase. Pool Test Kits - Further Reading
www.troublefreepool.com
- Rest of the World: pretty much only HornerXpress Worldwide in Fort Lauderdale, Florida (954-938-5355) or [email protected].
Long thread now, and don't recall - you added borites a week ago and plan to dump? How long on this fill and did you purge during?
TA can take some time to settle, don't expect to get a good reading right away. Also, did you say ph was rising? How much? Anything 7's is ok, and trying to change it with borites in the water is more "challenging".
Do you not have access to mercuric acid instead of dry acid? It seems to work better...
TA can take some time to settle, don't expect to get a good reading right away. Also, did you say ph was rising? How much? Anything 7's is ok, and trying to change it with borites in the water is more "challenging".
Do you not have access to mercuric acid instead of dry acid? It seems to work better...
- Jun 1, 2018
- 13,811
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Its not that muriatic acid works better its that dry acid adds sulfates to the water which build up & are not good for your swg. It is also more expensive than muriatic acid.
For the inconsistencies I would definitely say it’s the tester- aside from your goof lol
Pool Test Kits - Further Reading
- Rest of the World: pretty much only HornerXpress Worldwide in Fort Lauderdale, Florida (954-938-5355) or [email protected].
To be honest I don't think it's the tester, as it's pretty consistent when measuring from the same sample (eg: if I do 5 measurements, they will all be the same). The solution coloring changes to match the results as well (ie: more towards blue with higher TA, lighter green with lower TA). Did not add any water but we did have some guests in between those measurement which might have introduced some deodorant/detergent.
Yes, I added borates about a week ago. I wasn't really planning to dump at the time. The only reason I plan to do it next week is because I need to move the spa to have the heat pump installed and I can't do that if it's full of water. Yes, I did purge before fill. Some crud came out, not a whole lot. Almost 2 weeks since first fill/purge.
Speaking of my cloudy fill water, I have a whole house cyclone filer that I should clean weekly. I haven't been doing that lately but remembered to do it last week. YUCK! It took around 10 buckets to clean it, so no wonder my water wasn't looking that great when I filled. Thankfully I don't use the same water for cooking/drinking.
I do have muriatic acid. The reason I don't use it will sound very silly: I have 10% concentration and that's not in Pool Math, the minimum in the app is 15%. So every time I need to add acid, I need to do math, which I do not want
ps: links to article about sulfates do not work
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- Jun 1, 2018
- 13,811
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Hopefully since you cleaned your filter thingy your new fill will be less tumultuous.
About the tester - those that use an eye or colorimeter are known to be inaccurate/inconsistent overtime due their limitations and being affected by certain variables. Their very precise result numbers don’t necessarily mean they are that accurate. For most things you’re wanting to stick within a smaller range but it doesn’t have to be quite so precise so they surely beat out strips with large ranges. Titration would be best & has the least limitations & variances. Hopefully you can aquire an fas/dpd test soon & a turbidity test
as thats pretty important.
The others (ph,ta,ch) are very common here in 6 way tests and can be aquired at most hardware stores, not sure what its like there. So you could verify the accuracy of your current tester on a regular basis.
The sulfate article linked is about sulfates attacking concrete so it doesn’t really apply to your situation. The main thing is your expensive Swg cartridges- you want them to last as long as possible I presume?
About the tester - those that use an eye or colorimeter are known to be inaccurate/inconsistent overtime due their limitations and being affected by certain variables. Their very precise result numbers don’t necessarily mean they are that accurate. For most things you’re wanting to stick within a smaller range but it doesn’t have to be quite so precise so they surely beat out strips with large ranges. Titration would be best & has the least limitations & variances. Hopefully you can aquire an fas/dpd test soon & a turbidity test
as thats pretty important.
The others (ph,ta,ch) are very common here in 6 way tests and can be aquired at most hardware stores, not sure what its like there. So you could verify the accuracy of your current tester on a regular basis.
The sulfate article linked is about sulfates attacking concrete so it doesn’t really apply to your situation. The main thing is your expensive Swg cartridges- you want them to last as long as possible I presume?
Yup, meant "work out better" not "work better", but if using 10% and calculator calls for 15%, just add half-again as much. For example, if it called for 4 ounces of 15%, you add 6 ounces of 10%.
You can double check this by throwing some easy numbers at the math;
4 * .15 = .6 (ounces)
6 * .10 = .6 (ounces)
You can double check this by throwing some easy numbers at the math;
4 * .15 = .6 (ounces)
6 * .10 = .6 (ounces)
To be honest I'm more inclined to go with comfort over the longevity of the salt cell 
but since the math seems simple enough (thought I had to deal with muritatic acid solvent or whatnot) I'll be switching to that.
Went to take measurement today and nothing was working (circ pump normally runs continuously). Not the control panel, not the jets or heater, kind of like it wasn't powered.
Checked the breakers and they are all fine. Checked the connection in the spa and it's fine. Thankfully service is coming anyway on Thursday but maaaaaan am I bummed Didn't even get to use it for 2 weeks.
So I guess I'll be draining today...
but since the math seems simple enough (thought I had to deal with muritatic acid solvent or whatnot) I'll be switching to that. Went to take measurement today and nothing was working (circ pump normally runs continuously). Not the control panel, not the jets or heater, kind of like it wasn't powered.
Checked the breakers and they are all fine. Checked the connection in the spa and it's fine. Thankfully service is coming anyway on Thursday but maaaaaan am I bummed
Didn't even get to use it for 2 weeks. So I guess I'll be draining today...
Spa is back up and running. They replaced a power board (hope I understood correctly). Couldn't fully install the heat pump because they sent different pipes that were too small, so they'll still have to make another trip.
Good news is that my fill water is now crystal clear. That should teach me to clean the filter more often!
Did the acid/aeration dance for a good two hours yesterda. I estimate TA is now around 90 so I still have a bit to go. Using muriatic acid 10% this time around.
We also had the cover lift installed...man, does that make life easier!
Good news is that my fill water is now crystal clear. That should teach me to clean the filter more often!
Did the acid/aeration dance for a good two hours yesterda. I estimate TA is now around 90 so I still have a bit to go. Using muriatic acid 10% this time around.
We also had the cover lift installed...man, does that make life easier!