SWG Operation - Lessons Learned

[nater]

Bump. I think this one should be a sticky-lots of good info.

[Katy-Texas]

Just to add my 2 cents.

Have a 26000 gal in-ground plaster & gunite salt water pool for just over a year here in west side of Houston. Chemicals added are:

1) 1 gallon of acid every ~10 days to keep pH down in summer, about 1/2 that in winter.

2) Some cheapo Algaecide when I had some algae in skimmer entrances last summer. Then I read this forum and realized I was too cheap on power and upped my pump time to raise my Cl level to 2 since which I've had no more algae problem.

3) Added 3 x 4.5 lb jugs of stabilizer this spring when 1 year old as almost all disappeared over winter.

4) Couple bags of salt every 3 months, mostly as big rain dump overflows pool via overfill line to street thereby diluting the salt.

Teenage daughters want shower 1/2 time after pool, I never do, feels great.

I do still have quite a bit of spalling of flagstone (sandstone) coping, friend said he heard it was because I had salt pool? Whatever the reason I would not do flagstone again.

Lastly, all my friends with conventional Cl pools still have upsets once-twice a summer/year and get sold tonnes of chemicals from local stores.

Question 1, my pool builder said better to run salt generator at 50% for longer than 100% for shorter (and thereby save power) as hard on salt generator, unknown why?

Question 2, from reading this thread, sounds like vinyl salt water pool owners add way less acid than plaster owners, so something is going on with plaster. My plaster seems to be etching, ie becoming more porous, over time. Is that a negative side effect of salt plaster pools?

Thanks to pat for kicking off great thread, toodles.

[PatL34]

Thanks Katy for your response.

Your PB is correct in running longer at 50%, and once you have gotten used to the SWCG, you may be able to lower that setting.

The etching you mention could be a function of very low pH, if you are adding Muriatic Acid too much. pH should be between 7.2 - 7.6.

I still have not been able to understand why vinyl pools maintain a steadier pH than plaster pools. Plaster pools will always raise pH because of leaching from the walls, and particularly for new pools that are still being cured. How soon did you add salt after filling?

I waited at least a month before adding salt, after a replaster with Diamond Brite. Another possiblity is if sand was included in the plaster mix. This can be a reason for etching. That's why I had to replaster. The current pool plasterer demonstrated what happens when you don't have sand, by pouring 2 gallons of raw muriatic acid on the steps as the pool was filling up. If there had been any sand, it would have etched immediately.

Hope this helps.

Pat

[Katy-Texas]

Hi Pat

You say that I may want to lower SWCG from 50% I assume to extend it's life, but then I'd need to circ longer thus more power, guess it's a trade off.

Keep pH in 7.2-7.6 so don't think that's why etching.

Similar to you, pool builder added salt about 1 month after plaster & fill.

Thanks for ideas . . . cheers.

[SeanB.]

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.

[PatL34]

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

[PatL34]

Hi Pat

You say that I may want to lower SWCG from 50% I assume to extend it's life, but then I'd need to circ longer thus more power, guess it's a trade off.

The function of the SWCG is to generate chlorine, but in so doing, scale tends to build up on the cell membranes. This is removed by reversing the polarity to the membranes, and for this to work properly, the SWCG has to run at least 2 reversals to keep the membranes clear. Check with your manual for the default reversal settings, (usually 4 hours each, total 8) or call your SWCG vendor for more information on this.

Keep pH in 7.2-7.6 so don't think that's why etching.

Similar to you, pool builder added salt about 1 month after plaster & fill.

Thanks for ideas . . . cheers.

Hope this helps.

Pat

[Poolsean]

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.