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Our construction hasn't begun yet but our PB told us during our design session that we would use a chlorine floater for the first 10 days after filling the pool and then start up our swg. It will be a gunite pool with plaster. Is 10 days long enough, or should we wait longer?
Thanks.
Sean, Welcome to the forum.
I would wait longer. At least a month.
Unless your PB has prescribed what you should use in the floater, I would use a combination of regular unscented bleach and trichlor pucks. The pucks will add stabilizer (CYA) until you get to a 60 - 80 ppm level of CYA, and then use bleach exclusively.
Add muriatic acid ONLY to maintain pH at 7.2 - 7.6, and monitor the TA until it gets to about 80 ppm. Then adjust the return jets upwards to maintain that TA level while you are still curing, as it will help to keep the TA down and the curing.
The calcium hardness (CH) will rise naturally as the gunite is curing, so if you have the ability to use water that is no more than 200 ppm CH as initial fill I would do so. If you have to use well water, which I do NOT recommend, then a temporay filter that has the ability to remove metals and CH, HAS to be inserted in the delivery line.
BTW, make sure that there will be no sand in the gunite mix, as this can lead to pitting of the gunite at low pH as it is curing.
Hope this helps with your deliberations with your PB, and good luck.
Pat
Hope this helps.Quote:
Originally Posted by Katy-Texas
Pat
Pat, please, no offense intended by commenting on your responses.
Sean - regarding floating a tab feeder. There really is no reason that you can't start the Salt system up right away, with the exception of if the plaster manufacturer can void warranty if you do not wait a certain period of time. This point of view varies widely among the pool plasters.
I would be cautious with floating a tablet feeder, as it will tend to float and stick to one corner of your pool. Erosion of the tablets will also tend to fall out of the feeder and onto the plaster, where it has the potential to cause problems. Perhaps tethering it to a handrail or ladder rail, towards the deep end, rather than by the steps, where it will be even closer to the plaster.
KEEP AN EYE ON YOUR pH LEVEL!! This will cause more problems than anything else. Allow it to drift up, you will end up with calcium stalagmites all over your pool surface.
Per your suggestion to Katy, it's best to check with the manufacturer.
Pool Pilot has the ability to remember where it was in the forward or reverse polarity cycle when the pump shuts off. That way, when it starts back up, it will continue operating in the same direction so as not to cause uneven cell wear. This allows YOU to control how many hours per day you want to run your pump.
As MOST systems don't have this memory, your suggestion of even run times would be correct...but according to the specific Salt Chlorine Generator manufacturer. Everyone's reversal rates are different.
ie, Aquarite reverses every 100 minutes...therefore a run time in 200 minute increments (ie; 200 minutes (3 hrs 20 minutes pump run time - which I can't imagine anyone doing) / 400 minutes (6 hrs 40 minutes - more reasonable) /600 minutes (10 hrs - ahhhh, that's where the 10 hr pump run time comes from!) would ensure even cell wear.
Hope this helps.
Thanks for this thread, great info for pool-newbies like myself. :cool:
Very interesting. Are there considerations for winter storage in the North with several months of below freezing temperatures?
On Ebay I see there are several for $500 to $700. Any particular brand recommended? I saw Hayward Aquarite, The Pool Thing, Zodiac and Pentair for sale in that range.
Any caveats or raves or are they all about the same? Does one use the cell up quicker? Warranty and service support issues?
I have revised the intial post on this thread, to reflect discussions I had with Chem_Geek regarding the SWCG process.
The main difference is that the pH does not rise. It stays steady. This is the anomaly I saw with members mentioning this with liner pools. However with plaster pools the continuous leaching of calcium hydroxide, will raise the pH and so muriatic acid is needed accordingly. My apologies for any confusion this might have caused.
Pat
I have a fiberglass pool and have experienced a pH rise with my SWG. It is slow (and even slower now that I have 50 ppm borates in the water) but it is still happening.
Evan,
I suspect that there might be a slight loss of Cl that is not protected by the CYA, even though Richard (Chem_Geek) describes the SWCG operation somewhat as a "closed System". Ex-chemical engineers don't believe in "closed systems".:(
As Richard has mentioned, there are a lot of loose ends regarding the SWCG process that still need to be tied up. Your experience of rising pH is just one.
Pat
Good question. I just closed my pool in the Northeast, and it's my first year with the Autopilot. 2 questions:Quote:
Originally Posted by Spensar
1) Do any of you bring your cell manifold assembly inside for the winter?
and
2) Since I have the Autopilot control assembly in my shed, I would not be able to bring the cables inside. How would I winterize the cables if I remove the cell manifold assembly (I was thinking in tightly sealed plastic bags)
Tightly sealed bags should be sufficient. When re-opening in the summer, use a hair dryer to dry out the tri-sensor and cell connections on the cables and the cell manifold assembly.
Pat
Pat and Waterbear, (this is only ~ 4 mos late) Re: posts 34 - 36 on this thread - why didn't you ask me???? - I have access to large quantities of vynal liner stock, salt and the best test kit. If you'll give me the specifications for the experiment (I think I know what is required, but would rather you tell me how to set it up to get your required results ie., volume of water, ppm salt, sealed or open, what would the control be?, etc), I'll gladly perform it.
If this is now a 'non-issue' that's fine, but if you want me to do this, I'll need to know in the next week, as I'll be layed off in the next 2 weeks :) :) :D (aaaahhhh, winter!)
I understand that when I take H20, and NaCl and pass them across the electrically charged plates, I can see how H2 and Cl2 can be formed.
Since the H2 comes from water, the remaining oxygen will dissipate.
However the Cl2 come from NaCl. What happens to the sodium, where does it go?
At the cathode (the negatively charged plate), hydrogen is produced from either of the following reactions:Quote:
Originally Posted by cschnurr
2H+ + 2e- --> H2(g)
2H2O + 2e- --> H2(g) + 2OH-
Note that oxygen gas is NOT produced and does not dissipate. Instead hydroxyl ion (OH-) is created. Either of the above can be considered to be occurring since there is an equibrium that always exists in water between its split components, though the vast majority remains as the water molecule at normal pool pH:
H2O --> H+ + OH-
At the anode (the positively charged plate), chloride ion gets converted to chlorine gas that then dissolves in water to from hypochlorous acid and hydrochloric acid as follows:
2Cl- --> Cl2(g) + 2e-
Cl2(g) + H2O --> HOCl + H+ + Cl-
----------------------------------------
2Cl- + H2O --> HOCl + H+ + Cl- + 2e-
As you can see, the sodium doesn't participate at all in these reactions. When you add salt to water, it dissolves into its two components:
NaCl(s) + H2O --> Na+ + Cl- + H2O
Nothing happens to the sodium ion in a salt cell. Only the chloride ion participates in any reaction. The sodium ion does contribute to the general conductivity of the water. The area around the cathode accumulates negatively charged ions while the area around the anode accumulates positively charged ions so the sodium ion and hydrogen ion (which are positively charged) will tend to migrate from the anode to the cathode while chloride ion and hydroxyl ion (which are negatively charged) will tend to migrate in the opposite direction.
Now it is possible for another reaction to occur at the anode and competes with the production of chlorine as follows:
2H2O --> O2(g) + 4H+ + 4e-
So it is possible for oxygen gas to be produced in addition to chlorine, but due to the differential liklihoods (activation energies) of these two reactions, the production of chlorine is the primary reaction.
There are some websites that talk about "splitting" the sodium chloride as part of the electrolysis in the salt cell, but basically they have no idea what they are talking about. It is simply not true. Sodium Chloride (salt) "splits" all by itself when dissolved in water (in fact, that is how it is able to dissolve in water) and sodium has nothing to do with the electrochemistry of making chlorine.
Richard
Carl, though I don't have all the reactions in front of me - the sodium becomes NaOH (I believe that it's lye). One of the 'real' chemists could tell you better, but it does combine an subsequently effects the reactions. (If I recall correctly, there are a few (2) loose electrons that help other chems 'match up')
[edit]Whoops, Richard alredy answered[edit]
Thanks for the info.
I'm theorizing that as NaCl is regularly added to water a number reactions occur that free up Chlorine.
As the chlorine is used up to kill stuff and evaporates, then eventually the Na concentration in the pool will increase.
Similiar to CYA levels using stabilized pucks.
If it is correct, should I be concerned.
Carl,
Salt does not need to be regularly added to the water unless it is getting diluted through splash-out or backwashing. The consumption of chlorine in the water produces chloride ion so essentially the chloride ion is REGENERATED when the chlorine gets used up -- the chlorine/chloride does not (usually) evaporate. This happens regardless of whether the chlorine gets used up through oxidation (including disinfection) or through breakpoint with ammonia/urea or through breakdown from sunlight.
The only way that chloride will leave the system on its own (i.e. without sodium) is if there is outgassing of chlorine gas or hypochlorous acid gas. Both can outgas from a pool with hypochlorous acid being about 100 times faster to outgas (it's equilibrium quantity as a gas is much higher than for atomic chlorine gas). However, such chlorine outgassing is very slow and minimal in a pool. By far, most chlorine in a pool gets used up through the breakdown by sunlight and therefore gets regenerated back into chloride ion.
So the bottom line is that though it is true that theoretically you can build up sodium ion by having to add salt to make up for the lowering of chloride ion through the outgassing of chlorine (hypochlorous acid), the amount is exceptionally small. Anyone who has an SWG pool with a cartridge filter can probably tell you that they need to add very little salt to maintain the salt level (which is actually measuring chloride ion though the units are in ppm sodium chloride).
You can see the equations for chlorine consumption (and generation in a salt cell) at this link where you can see that the net reaction of chlorine generation AND consumption in an SWG system is:
4H2O + 2Cl- --> 2HOCl + 2OH- + 2H2(g)
2HOCl --> O2(g) + 2H+ + 2Cl-
2H+ + 2OH- --> 2H2O
------------------------------------------
2H2O --> 2H2(g) + O2(g)
6H2O + 3Cl- --> 3HOCl + 3OH- + 3H2(g)
2NH3 + 3HOCl --> N2(g) + 3H+ + 3Cl- + 3H2O
3H+ + 3OH- --> 3H2O
------------------------------------------------------
3H2O + 2NH3 --> N2(g) + 3H2(g)
So the net reaction of chlorine generation AND consumption in an SWG system is that you simply produce hydrogen and oxygen gasses if the chlorine breaks down from sunlight (which is what most of it does) or you produce nitrogen and hydrogen gasses if the chlorine burns up (so to speak) ammonia. Other reactions are possible, but these are the common ones. Chlorine can combine with organics, but generally sunlight breaks these down and liberates the chloride ion (carbon dioxide may also be produced in this process).
Richard
OOPS! Wrong "Carl"!!!!:p:D