Dry Ice (Solid CO2) added to pool for Halloween effects.

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Found this info: http://www.anotherperfectpoolnews.com/w ... nwater.pdf

CO2 in Pool Water #4
CO2 can also be added to pool water by simply injecting pure CO2 into the water, or by
adding dry ice (frozen CO2) to water. The pH will drop, and if a large amount of CO2 is
absorbed into the water, the pH could go below 6.0. Despite the fact that the pH could be
lowered dramatically, no change or reduction will occur in the alkalinity under this
scenario. This fact bears repeating because it is incorrectly being taught in some
seminars. The amount of CO2 in water does not affect the content of alkalinity, only the
pH is affected.
 
Yes I've been reading about CO2 injectors and some state that the Alkalinity rises others that it does not but on the whole it appears the majority say that it does not.

Dry Ice is not really an option here in Europe as it is quite expensive so I'll have a look at professional CO2 automated systems. Just need to find out now if liquid chlorine has any reaction to Carbon dioxide as I use automatic chlorination and would hate to have an incident with CO2 and chlorine mixing in the pipe work.

Thanks for the link, interesting reading indeed.
 

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knutohotub said:
Would this be ok to use in a HT and could you actually soak while it's floating around?
Click to expand...
Dry ice can be dangerous. It is very cold, and can cause frostbite if it contacts bare skin. As it sublimates (converts from ice to gas), it can displace oxygen leading to the risk of asphyxiation.
 
Guys, you are missing the whole point. Yes, adding carbon dioxide to pool water lowers pH with no change in TA and is the exact opposite of carbon dioxide outgassing. However, if your pH is rising due to carbon dioxide outgassing, then adding carbon dioxide to the pool doesn't reduce that rate of pH rise. You are just going to yo-yo between adding carbon dioxide and having it outgas. If you were instead to add a strong acid to lower the pH and TA together, then the lower TA will reduce the rate of carbon dioxide outgassing and the rate of pH rise. That is, it solves the problem instead of masking it.
 
chem geek said:
Guys, you are missing the whole point. Yes, adding carbon dioxide to pool water lowers pH with no change in TA and is the exact opposite of carbon dioxide outgassing. However, if your pH is rising due to carbon dioxide outgassing, then adding carbon dioxide to the pool doesn't reduce that rate of pH rise. You are just going to yo-yo between adding carbon dioxide and having it outgas. If you were instead to add a strong acid to lower the pH and TA together, then the lower TA will reduce the rate of carbon dioxide outgassing and the rate of pH rise. That is, it solves the problem instead of masking it.
Click to expand...

Richard I hear what you are saying, but..

In my situation where I use a great deal of liquid chlorine which despite what anybody else says raises the PH quite a bit. I use small amounts of acid to drop the PH but as we all know the TA drops as well, any introduction of Sodium Bicarb to counter the very low TA's I get.. 15ppm or less sometimes will raise the PH right back up and in no time at all. I quite often get a situation where I have PH 7.8/7.9 and a TA of less than 20 PPM. Even with low TA's any Sodium Bicarb added even at these highish PH levels results in a moderate TA increase coupled with a PH rise which then needs reducing. I maintain 9 residential pools and all without fail all react in the same manner. I had read many places that adding sodium bicarb raises the TA and slightly raises the PH.. Well I'm afraid that this is just not true. Adding sodium bicarb with the aim of raising TA a mere 10ppm to a pool with a TA of 20 and PH 7.8 you will notice a marked increase in PH

Now if I introduced some C02 into the water and at the same time added Sodium Bicarb then the end result should be an increase in TA alone. Now I know it will probably not work out quite how I'd like but given my current situation I'm happy to try anything to get my TA's up to at least 50/60 ppm. I'm thinking of getting a CO2 fire extinguisher and giving a go before spending too much on the idea.
 
You should see if you can get a better source of chlorinating liquid or bleach that doesn't have so much excess lye in it. Yes, there is excess lye, but high-quality chlorinating liquid, such as that from Odyssey Manufacturing, Co., only has a pH of 12.5 and 0.2-0.3% excess lye (sodium hydroxide). Clorox Regular 6% bleach has a pH of 11.9 and less than 0.06% excess lye. With the good chlorinating liquid, the pH would rise from 14 ppm FC (about one week if 2 ppm per day) from 7.5 to 7.53 if the TA were 80 ppm. If one has chlorinating liquid with a pH of 13 and 0.8% excess lye, then the pH would rise to 7.6. If one used poor bleach (as with many off-brand Ultra bleaches) with a pH of 13 then the pH would rise to 7.7.

As for baking soda, raising the TA by 10 ppm from 70 to 80 would raise the pH from 7.5 to 7.54 IF there were no carbon dioxide outgassing, but if you add the baking soda quickly then you concentrate the TA near the surface which can have carbon dioxide outgas causing the pH to rise more. This is one situation (unlike with acid addition) where you can influence the amount of pH rise based on how you are adding the baking soda. So yes, in that situation you can use carbon dioxide to lower the pH back down since it is just replacing the carbon dioxide that outgassed.
 
Thanks Richard that is a good explanation of why I get such high PH rises with the addition of Sodium Bicarb. I mix my Sodium Bicarb thoroughly and pour it into the deep end of the pools so that it quickly sinks to the bottom.

Oh and Europe is not only years behind you guys in the States in how to correctly look after a swimming pool they are also well behind you in producing quality chlorine so getting my hands on what you guys use is not an option. Hence my constant fight with high PH's as the stuff sold over here has a very high PH.
 
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