Dave H Posted December 9, 2005 Report Share Posted December 9, 2005 Can anyone please offer some advice….I have just purchased a new spa (1500 litres capacity) and am struggling to keep the Ph down. The Spa was commissioned late evening 30 Nov 2005. The following day I chlorine shocked it to 20ppm. Once chlorine had abated, I inserted Spa frog cartridges set as per manufacturers instructions. Bromine levels took a few days to build up but are now ok. The problem is with the Ph which settled ‘post shock’ at 8.4 Over the last week I have dosed the spa with over 100 ml (measured dry in the scoop) of dry acid in numerous applications. I can get the ph down by this method, but the next day it is back around the 8 mark. I invested in a good pool test kit and on 07 Dec checked TA levels which were really low (less than 50 ppm !!) Having read threads on this subject I concentrated on the TA levels and have now got it back to around 100 ppm using bicarb and draining/refilling about 8 inches of water. I dosed the spa with 2 x 10 ml dry acid in 2 separate doses yesterday and got the ph down to 7.55. This morning it is back to 8.1 ! Base tap water readings are Ph – 7.4. TA – 120 CH – 175 Can anybody offer some logical explanation as it’s doing my head in…thanks…(and sorry about the length of this) Dave H Quote Link to comment Share on other sites More sharing options...
Jim_The_Jim Posted December 9, 2005 Report Share Posted December 9, 2005 Can anyone please offer some advice….I have just purchased a new spa (1500 litres capacity) and am struggling to keep the Ph down. The Spa was commissioned late evening 30 Nov 2005. The following day I chlorine shocked it to 20ppm. Once chlorine had abated, I inserted Spa frog cartridges set as per manufacturers instructions. Bromine levels took a few days to build up but are now ok. The problem is with the Ph which settled ‘post shock’ at 8.4 Over the last week I have dosed the spa with over 100 ml (measured dry in the scoop) of dry acid in numerous applications. I can get the ph down by this method, but the next day it is back around the 8 mark. I invested in a good pool test kit and on 07 Dec checked TA levels which were really low (less than 50 ppm !!) Having read threads on this subject I concentrated on the TA levels and have now got it back to around 100 ppm using bicarb and draining/refilling about 8 inches of water. I dosed the spa with 2 x 10 ml dry acid in 2 separate doses yesterday and got the ph down to 7.55. This morning it is back to 8.1 ! Base tap water readings are Ph – 7.4. TA – 120 CH – 175 Can anybody offer some logical explanation as it’s doing my head in…thanks…(and sorry about the length of this) Dave H It sounds to me like you are using a chlorine shock that raises pH. As I recall in Canada the use of that sort of shock is common. What is the chemical name of the product you are using? Normally we recommend shocking to 10 PPM and that seems to do the job. I also recommend trying a "non chlorine shock", with the chlorine that will cut the pH effects of the shock. Is it Lithium shock? With this you may need to lower the TA starting point as well. Quote Link to comment Share on other sites More sharing options...
Dave H Posted December 10, 2005 Author Report Share Posted December 10, 2005 It sounds to me like you are using a chlorine shock that raises pH. As I recall in Canada the use of that sort of shock is common. What is the chemical name of the product you are using? Normally we recommend shocking to 10 PPM and that seems to do the job. I also recommend trying a "non chlorine shock", with the chlorine that will cut the pH effects of the shock. Is it Lithium shock? With this you may need to lower the TA starting point as well. Jim, thanks for the reply... I have used Fi-Clor shock..the package states it is a new product and is calcium hypochlorite containing 78% available chlorine. As a matter of interest I shocked the spa earlier today with Fi-Clor Non Chlorine shock. This reduced the Ph from 8.1 to 7.8...post session tonight it is back up to just over 8....will see what tomorrow brings !! Quote Link to comment Share on other sites More sharing options...
Jim_The_Jim Posted December 10, 2005 Report Share Posted December 10, 2005 Jim, thanks for the reply... I have used Fi-Clor shock..the package states it is a new product and is calcium hypochlorite containing 78% available chlorine. As a matter of interest I shocked the spa earlier today with Fi-Clor Non Chlorine shock. This reduced the Ph from 8.1 to 7.8...post session tonight it is back up to just over 8....will see what tomorrow brings !! Cal Hypo is a pool shock, commonly used in the US. I would be interested to see what the manufacturer of the shock states the pH is. Typically it is fairly neutral compared to non chlorine shock. The TA will constantly bring the pH up as long as there are no acids being introduced into the water. The TA's job is to fight against acids in the water and to raise the pH as the acids keep lowering the pH. Start with a lower TA and see what happens. Try 10 PPM increments until you get a very slight rise in the pH over a week. Quote Link to comment Share on other sites More sharing options...
Dave H Posted December 10, 2005 Author Report Share Posted December 10, 2005 Cal Hypo is a pool shock, commonly used in the US. I would be interested to see what the manufacturer of the shock states the pH is. Typically it is fairly neutral compared to non chlorine shock. The TA will constantly bring the pH up as long as there are no acids being introduced into the water. The TA's job is to fight against acids in the water and to raise the pH as the acids keep lowering the pH. Start with a lower TA and see what happens. Try 10 PPM increments until you get a very slight rise in the pH over a week. Just checked the spa this morning...Ph back to 8.15 and TA has dropped from 90 yesterday to 80 today. When you say a slight rise in the Ph do you actually mean a lower number which is what I'm after...sorry i'm new to all this Quote Link to comment Share on other sites More sharing options...
Jim_The_Jim Posted December 10, 2005 Report Share Posted December 10, 2005 Just checked the spa this morning...Ph back to 8.15 and TA has dropped from 90 yesterday to 80 today. When you say a slight rise in the Ph do you actually mean a lower number which is what I'm after...sorry i'm new to all this It is better to have a slight rise in pH over a week 7.8 is a good aim point, but 8.0 is easy to bring back down. If you start with 7.2 to 7.4 and after a week it goes up to 7.8 that would be just about perfect. It is difficult to get, because the use of the spa will have an effect on the pH. More use more pH changes. If the use per week is consistent, it is a lot easier. It is better to have a slight rise in pH, because if you let the TA drop to a point where the pH falls, it falls hard and can drop into the 6.5 range very quickly without a TA buffer support. If you started with 90 and it went too high over one day, that is not good. Start with 70PPM and see what happens. The idea is to not spend all your spare time testing and adjusting the water. Once a week on a normal used spa or twice a week on a heavily used spa is normal. There is also a wonderful product called "pH Magic" that is a "high buffer". It works very well to stop the pH from getting above 7.6. Basically it is "boric acid". Quote Link to comment Share on other sites More sharing options...
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