Thank you mgftp, your explanation is very clear. We will add 2L liquid chlorine today. How about the TA 110, can I leave it till rain water bring the level down? Also with ph 7.6, can I leave TH 200 as it is? And how many hours per day would you recommend to run the pool pump ? Thanks again.
Need help to start newly filled retiled old pool
- Thread starter minidolphin
- Start date
- Mar 5, 2020
- 3,202
- Pool Size
- 66000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V35
TA is not a terribly important parameter. It's more that it's annoying to have pH rise too quickly when TA is too high. Usually TA comes down over time on it's own with acid additions to bring pH down when required, as long as no baking soda is added.
You are testing with the CCL kit? Then your Hardness would be Calcium Hardness (CH), not Total Hardness. And it is CH that we are interested in.
In the end you want to find a combination of CH and TA, that give you a CSI (Calcium Carbonate Saturation Index) that isn't too low (risk for etching of the pool plaster), and not too high (risk for scale formation). With a SWG, scale can form quicker in the SWG cell than on pool surfaces because of the locally increased pH in the cell, for this reason we like to keep CSI between -0.3 and 0 (and not -0.3 and +0.3 as for plaster pools without SWG).
Turn on temperature and CSI tracking in PoolMath, and play around with the numbers a bit. You want CSI to be more or less in above range over the range that your pH changes between acid additions. Also consider that CSI will be lower in winter due to lower water temperature.
Adjust your CH based on that. You might want it a bit higher, maybe around 300.
This also depends on the CH of your fill water. If that is high in CH, then the pool CH can creep up over time as you replace evaporation losses (which leave the calcium behind) with fill water that adds more calcium. Unless you get a lot of rain in winter creating overflow (or requiring manual draining when the pool is too full) which flushes calcium out. Until you get a feel for how your CH develops over time, you don't want to go too high.
Your current TA is probably not bad with your current CH, and going into winter. It's OK to keep pH a bit higher in winter to compensate for the effect of colder water on CSI. It's also OK if CSI gets a bit below -0.3 in winter, but you really don't want it below -0.6.
You are testing with the CCL kit? Then your Hardness would be Calcium Hardness (CH), not Total Hardness. And it is CH that we are interested in.
In the end you want to find a combination of CH and TA, that give you a CSI (Calcium Carbonate Saturation Index) that isn't too low (risk for etching of the pool plaster), and not too high (risk for scale formation). With a SWG, scale can form quicker in the SWG cell than on pool surfaces because of the locally increased pH in the cell, for this reason we like to keep CSI between -0.3 and 0 (and not -0.3 and +0.3 as for plaster pools without SWG).
Turn on temperature and CSI tracking in PoolMath, and play around with the numbers a bit. You want CSI to be more or less in above range over the range that your pH changes between acid additions. Also consider that CSI will be lower in winter due to lower water temperature.
Adjust your CH based on that. You might want it a bit higher, maybe around 300.
This also depends on the CH of your fill water. If that is high in CH, then the pool CH can creep up over time as you replace evaporation losses (which leave the calcium behind) with fill water that adds more calcium. Unless you get a lot of rain in winter creating overflow (or requiring manual draining when the pool is too full) which flushes calcium out. Until you get a feel for how your CH develops over time, you don't want to go too high.
Your current TA is probably not bad with your current CH, and going into winter. It's OK to keep pH a bit higher in winter to compensate for the effect of colder water on CSI. It's also OK if CSI gets a bit below -0.3 in winter, but you really don't want it below -0.6.
Reagents are expensive, save them. There's no need for that high of resolution on the FC test. Use 10mL of water and 1 scoop of powder. Then each drop = .5 FC. For example: 10 drops = 5 FC.
Thanks for taking the time to explain it clearly to me mgtfp. Our test kit is Taylor k2006 Salt. Here are the result we've just taken this evening: FC 4.5ppm, CC 0.5ppm, PH 7.6, Temp 24.8 degrees C, CSI -0.25 according to PoolMath. It is between -0.35 and 0, so it looks like we don't need to add anything to adjust, am I right?
(yesterday test results: TA 110ppm, CH 200ppm, CYA 25)
- Mar 5, 2020
- 3,202
- Pool Size
- 66000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V35
Thanks for taking the time to explain it clearly to me mgtfp. Our test kit is Taylor k2006 Salt. Here are the result we've just taken this evening: FC 4.5ppm, CC 0.5ppm, PH 7.6, Temp 24.8 degrees C, CSI -0.25 according to PoolMath. It is between -0.35 and 0, so it looks like we don't need to add anything to adjust, am I right?
Yes, for now you should be OK. Going into winter, your CYA is OK around thirty. Going into summer you'll want that a bit higher, which will lower CSI.
Over winter, pH rise should also not be too much of an issue as long as you accept to keep it a bit higher, so the higher TA shouldn't be too much of an issue. Everything chemical in the water slows down with colder temperatures, including the CO2 outgassing that causes pH to rise.
In summer, the pH rise might become too annoying, and you might want to bring TA down a bit then. Then you'll probably have to increase CH a bit. Would helpful if you could test the CH of the tap water you use for topping up pool water, this will give us an idea if CH will trend upwards over time
Just keep an eye on CSI. If you think it's trending down too much then reach out and we'll reconsider. If CH gets further down with winter rains then I would bring CH up a bit.
Thank you mgtfp, for highlighting all the very important points on managing the pool water chemical and you've explained it so clearly that we have a good grasp on the logic behind them. We'll post the tap water CH here once tested.
- Mar 5, 2020
- 3,202
- Pool Size
- 66000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V35
OK, that's a fair bit higher than my tap water, which has CH 30-40ppm.
Depending on the rain you get on a yearly average, I reckon that your pool CH will creep up over time as you top up evaporation loss. Unless CH drops a lot with winter rains, I would hold off with increasing CH for now. Maybe increase it to 250ppm, but I wouldn't go higher for now.
Watch your CSI and don't let pH and TA drop too low for now. Once you get a feel for how CH develops over summer, you'll see if increasing CH makes sense.
Hi mgtfp, I have to correct the previous CH tap water test result posted earlier, 150ppm was actually pool water (hubby took instruction incorrectly from me, who currently away from home). Tap water CH 70. The pool water was tested again this afternoon 45 mins after the rain stopped (pump was on). Pool water FC 4, CC 1, pH 7.1, CH 150, temp 23.2 degrees. I got CSI result -0.87. (5 days ago Ta 110, CYA 25). I think the CSI is too low, what do I need to add first?
- Mar 5, 2020
- 3,202
- Pool Size
- 66000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V35
I'd bring CH up to about 250ppm and take it from there.
Has hubby recently added acid, or currently using chlorine tabs? pH 7.1 is quite unusual with TA 110. Might be good to confirm TA.
Has hubby recently added acid, or currently using chlorine tabs? pH 7.1 is quite unusual with TA 110. Might be good to confirm TA.
Thanks for your response mgtfp. I will checked with him if he added acid. we bought 4kg Calcium chloride before. To increase CH from 150 to 250ppm, we can use this one, but on its package it says Calcium Chloride will increase Alkalinity, so we will test TA first before adding Calcium Chloride tomorrow.
Hi mgtfp, the combined chlorine has increased from 0 to 1ppm in the last 4 days. what causes this do you think and how to keep it low? we have not used the at all since filled with water.
- Mar 5, 2020
- 3,202
- Pool Size
- 66000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V35
I missed the CC when I read your post. Had the pool been used a lot over Easter? Pool party? CC usually come from chlorine partially oxidising things like sweat, urine. Kids peeing in the pool for example.
Let's call your CYA 30, better to round up for the purpose of using the FC/CYA chart. Then your target range is up to 6. Maybe try to stick closer to the upper end of the target range, that should help to deal with CCs quicker. And anything up to SLAM is safe to swim in, which would be 12 in your case. Stay rather too high than give chlorine drop too low at any time. Even a short stint below min FC can turn ugly.
As a comparison, my CYA is usually between 60-80. I usually keep my FC around 10. Sometimes it creeps up to about 14 or so when there's a longer cloudy stint (bloody Melbourne...). Still no chlorine noticeable. But I don't like my FC to drop much below 10.
Regarding the Calcium Chloride: I don't really see how that would increase Alkalinity. I could imagine that - should CSI already by quite high when adding calcium chloride - Alkalinity could decrease because the added calcium could react with carbonate (that's what Alkalinity mostly measures) and fall as calcium carbonate (i.e. scale) out of solution and effectively removes alkalinity from the water.
But yes, test TA before and after adding calcium chloride. Curious about the results.
Also keep an eye on FC after adding calcium chloride. There are some cases where people reported FC plummeting afterwards. It shouldn't happen, and we haven't really understood the reason. Maybe impurities in the product. So, just keep an eye on it.
Let's call your CYA 30, better to round up for the purpose of using the FC/CYA chart. Then your target range is up to 6. Maybe try to stick closer to the upper end of the target range, that should help to deal with CCs quicker. And anything up to SLAM is safe to swim in, which would be 12 in your case. Stay rather too high than give chlorine drop too low at any time. Even a short stint below min FC can turn ugly.
As a comparison, my CYA is usually between 60-80. I usually keep my FC around 10. Sometimes it creeps up to about 14 or so when there's a longer cloudy stint (bloody Melbourne...). Still no chlorine noticeable. But I don't like my FC to drop much below 10.
Regarding the Calcium Chloride: I don't really see how that would increase Alkalinity. I could imagine that - should CSI already by quite high when adding calcium chloride - Alkalinity could decrease because the added calcium could react with carbonate (that's what Alkalinity mostly measures) and fall as calcium carbonate (i.e. scale) out of solution and effectively removes alkalinity from the water.
But yes, test TA before and after adding calcium chloride. Curious about the results.
Also keep an eye on FC after adding calcium chloride. There are some cases where people reported FC plummeting afterwards. It shouldn't happen, and we haven't really understood the reason. Maybe impurities in the product. So, just keep an eye on it.
He said he no. We did not buy chlorine tabs just liquid chlorine. it's been rainning heavily in th elast 3 days and the pool water overflows. I will ask him to do the test after rain stops and lets see what the rain does to CH and other chemicals. I will report here again. Thanks
No, it has not been used at all since the pool was filled with water, but I could see some organic matter (from leaves dropping) in the bottom because it has not been vacuumed. May be that is the reason for CC increase
Thank you for all these good advice above mgtfp.I missed the CC when I read your post. Had the pool been used a lot over Easter? Pool party? CC usually come from chlorine partially oxidising things like sweat, urine. Kids peeing in the pool for example.
Let's call your CYA 30, better to round up for the purpose of using the FC/CYA chart. Then your target range is up to 6. Maybe try to stick closer to the upper end of the target range, that should help to deal with CCs quicker. And anything up to SLAM is safe to swim in, which would be 12 in your case. Stay rather too high than give chlorine drop too low at any time. Even a short stint below min FC can turn ugly. Ok we will tryo to keep FC 6 and higher
As a comparison, my CYA is usually between 60-80. I usually keep my FC around 10. Sometimes it creeps up to about 14 or so when there's a longer cloudy stint (bloody Melbourne...). Still no chlorine noticeable. But I don't like my FC to drop much below 10.
Regarding the Calcium Chloride: I don't really see how that would increase Alkalinity. I could imagine that - should CSI already by quite high when adding calcium chloride - Alkalinity could decrease because the added calcium could react with carbonate (that's what Alkalinity mostly measures) and fall as calcium carbonate (i.e. scale) out of solution and effectively removes alkalinity from the water. I see...
But yes, test TA before and after adding calcium chloride. Curious about the results. Yes, will do the test. It's been been drenching here in Sydney for the last 3 days, the pool water is overflow and we used pump to remove some of the water. Will test when the rains stops.
Also keep an eye on FC after adding calcium chloride. There are some cases where people reported FC plummeting afterwards. It shouldn't happen, and we haven't really understood the reason. Maybe impurities in the product. So, just keep an eye on it. Ok we'll keep an eye on that.
- Mar 5, 2020
- 3,202
- Pool Size
- 66000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V35
No worries. You'll have that all worked out in no-time.
See how you go once that rain had calmed down. Don't let FC drop in the meantime. And make sure you let that rain mix in properly before you test and adjust.
Dont let the pool water overflow the coping. Drain some off before it reaches the coping or water damage can happen.He said he no. We did not buy chlorine tabs just liquid chlorine. it's been rainning heavily in th elast 3 days and the pool water overflows. I will ask him to do the test after rain stops and lets see what the rain does to CH and other chemicals. I will report here again. Thanks
If its overflowing through a dedicated overflow pipe, then carry on.
Thanks for the warning Bperry, we wouldn't know overflow water can damage pool. There is no overflow pipe anywhere.Dont let the pool water overflow the coping. Drain some off before it reaches the coping or water damage can happen.
If its overflowing through a dedicated overflow pipe, then carry on.
Tommorow will test the water after vacuum. thanks