SWG Operation - Lessons Learned

[salinda]

Can you tell me what drop-type salt test I should use? I have been using the strips that you put in a small vial of water and wait a few minutes to take a reading.

Also, regarding the potential damage to tile/coping etc., I have found only the opposite. I have a Calcium reading on the high side (520 ppm). My overflow from my spa always had a lot of scale. Since the swg has been in operation, the scale has actually been disappearing. Maybe I am just more aware of ph and adding muriatic acid more often.

I do use A LOT of acid--at least 1/2 gallon/week with a 37,000 gallon pool.

[PatL34]

Can you tell me what drop-type salt test I should use? I have been using the strips that you put in a small vial of water and wait a few minutes to take a reading.

Also, regarding the potential damage to tile/coping etc., I have found only the opposite. I have a Calcium reading on the high side (520 ppm). My overflow from my spa always had a lot of scale. Since the swg has been in operation, the scale has actually been disappearing. Maybe I am just more aware of ph and adding muriatic acid more often.

I do use A LOT of acid--at least 1/2 gallon/week with a 37,000 gallon pool.

The salt water test kit is from Taylor, (Item # K-1766) which you can order from your local pool store. I don't think Taylor likes to sell to the public direct. Test your salt level at least once a week while removing the scale and then once a month when your pool chemistry is balanced. Use the salt test strips only as a rough guide.

A calcium reading of 520 ppm is definitely on the high side, so keeping the pH down to between 7.2 to 7.6 will definitely help. You will be using a lot of acid during this time. 300 ppm CH is your goal. The TA should be checked as well, and if above 150 ppm, I would start aerating to bring it down using a low pH down to 120 ppm. Hopefully your scale should disappear even faster.

Check your cell once a month too.

Hope this helps.

Pat

[salinda]

Pat, I have very little scaling now--less since the swg was installed (not what I expected, but it's great!). My TA is only 90 according to the PS233. My system is well-balanced except for the Ca level and that is the same as last fall when I closed. The cell on my Clearwater is clear so I visibly check it often and I did do a muriatic acid soak on it at the beginning of this spring. Why would the salt level change "while removing scale?" I had to adjust my salt level this spring because we got soaked this winter in California and my water was very diluted, but now we won't see rain until next fall so the salt level should be fixed.

Doesn't the salt water test use silver, which is expensive? That's probably why they don't have too many in stock.

[PatL34]

Pat, I have very little scaling now--less since the swg was installed (not what I expected, but it's great!). My TA is only 90 according to the PS233. My system is well-balanced except for the Ca level and that is the same as last fall when I closed. The cell on my Clearwater is clear so I visibly check it often and I did do a muriatic acid soak on it at the beginning of this spring. Why would the salt level change "while removing scale?" I had to adjust my salt level this spring because we got soaked this winter in California and my water was very diluted, but now we won't see rain until next fall so the salt level should be fixed.

Doesn't the salt water test use silver, which is expensive? That's probably why they don't have too many in stock.

You might have had some scale on the salt sensor which is now clearing up.
You should be able to get the salt water test kit easily. The chemical used is silver nitrate. This reacts with potassium dichromate indicator to give the red color of potassium nitrate.

The reason they don't have too many in stock, is that the test kit at $25, lasts a LOT longer than the test strips at about $8.00, a third of the price. They would rather you buy test strips.

Hope this helps.

Pat

[PoolDoc]

You might have had some scale on the salt sensor which is now clearing up.
You should be able to get the salt water test kit easily. The chemical used is silver nitrate. This reacts with potassium dichromate indicator to give the red color of potassium nitrate.

The reason they don't have too many in stock, is that the test kit lasts a LOT longer than the test strips at about a third the price, about $8.00.
Pat

Hi Pat,

It looks like you've created a thread worth making a 'sticky', but it's a bit cluttered with followup OT items. If you would, post a copy again, and then PM me when you have done. I'll add a 'threatening' follow-on , asking people who know (including Sean & Mark) to offer corrections. Once corrected (something I can't do, never having had a SWG), I'll 'sticky' it.

Oh, and about the K-1766 -- were you really able to get one for $8? It currently lists for $20.75, and I thought I was offering a real deal on the PS234S. But, if you can get one for $8, it's not a deal. AgNO3 prices *are* way up, so it's possible that the older price was much lower -- I haven't looked through old Taylor price lists. And, a very quick 'Google' for K-1766 showed prices between $24 and $35.

Ben

[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.