Switching from SWCG to liquid Chlorine.

[kelemvor]

I agree, something's not right with that level of scaling. Perhaps really high pH and really high calcium? In any event, to switch to regular chlorination, all you have to do is start dosing chlorine. I don't think you'll know how much to add on a regular basis until you get a feel for it.

Use the traditional method. Identify your target chlorine level based on your CYA reading and the best guess chart. Then dose chlorine accordingly. Take regular chlorine readings and re dose as needed.

With a 50 cya you want to be between 3-6ppm FC. It takes a little less than a quart of 6% bleach to give you 1% raise in FC in that much water.

You've almost certainly got some other problem leading to the severe scaling though, I'm sure it will manifest its-self in other ways if you don't find and correct that problem.

[poolaris]

The numbers are as follows: FC=3.0 TAC = 3.0, Salt= 4500, CH = 350, CYA=50, TA= 120,PH = 7.4, PHO =1500. Those numbers were obtained today from a pool store test and were very close to readings I obtained using the Taylor drop test kit excepting those for salt and PHO which I was unable to test myself but the TA reading they had was 20 higher than mine. I assume all that white stuff between the cells is calcium? Anyway, it completely bridges the cell plates - always has. It should be cleaned twice a day and sometimes is. I just thought that was one of the downsides of SWG. 30 years before that I had a pool in which I used tabs but I don't remember spending so much time in maintaining it as this one which I have had for six years. Of course time dims the memory. The other noticeable difference in this one is the amount of scaling on the perimeter tiles as they are virtually light gray and pumice stone rubbing has no effect. The other difference is the constant need to add acid. After this I do not want another SWG even so called self cleaning. I'm not saying my scaling is the result of the SWG as my water has always been crystal clear, I'm just wanting to save some time in the mornings.

[CarlD]

I am guessing here but I think 1) your salt is too high. 3000ppm is the usual target. 2) If your pool is vinyl there is NO reason your CH is 350...again, too high. If it's concrete or tile, try lowering CH to 200. If vinyl, consider replacing the water with virtually 0 CH. 3) Your CYA should be a minimum of 60 for your SWCG (check your manual) 4) I think your T/A is too high, especially with CH=350. You'll want that down, too. 5) If PHO is phosphates, that's probably irrelevant. 6) You should also have the pool store check for all kinds of metals.

But, as I said, I'm just guessing here.

[BigDave]

How warm is the water?

[poolaris]

Pool Store did test for copper & iron which were zero. Water temp is between 70-76. I have already turned off SWG and will check CL twice a day and add liquid CL as necessary to maintain 3.0. Yes, PHO was Phosphates, which was high because of high winds with leaf and catkin debry. In spite of keeping pump on all the time during those periods and manually vacuuming, I guess it still crept up. Pool store tried selling "Phosfree". I thought it was a rip, but maybe I was wrong?

[poolaris]

I forgot to add that my pool is concrete. Also Zodiac recommend a salt level of 4200. Last year when I had it tested it was 3800, and as I have not added any salt I think it must be in that ballpark at the moment. Is there any disadvantage in having salt in pool and using liquid chlorine as the sole method of sanitizer?

[kelemvor]

Is there any disadvantage in having salt in pool and using liquid chlorine as the sole method of sanitizer?

Nope. Some people add salt with no swcg because they like the way the water feels with the salt in it.

[chem geek]

With your reported numbers, the saturation index is -0.16 so shouldn't be scaling that much unless your pH is getting higher at times. It's also possible to get calcium phosphate scaling and that might be what is happening in your case. A phosphate remover would help if that were the case, but they are expensive so would not be cheap if it turned out not to be the cause. If you were to lower the TA to 80 ppm and see what happens -- especially since with an SWCG you would normally see the pH rising so it might be higher -- that would be cheaper to try first. If that helped, then you could lower the TA even more to 70 ppm and then add 50 ppm Borates to the pool and that should cut down the amount of pH rise in the SWCG in half.