Startup Salt Calcs questions

[kicksavedave]

Hi all you pool geniuses, first post on here, thanks for giving us pool dummies a place to get smarter.

So I started up a newly pebble tec resurfaced pool on April 20, now its time to add the salt for the SWQ to do its thing. I calculated ~32800 gallons, I was able to use a tape measure to get the deep end depth (used to be a diving board so its 9 feet) and entered my dimensions in the Pool Math to get 33.8K gallons. Pool Math calculated it would need 961 lbs of salt to get to 3500 ppm, so I bought 1200 (30 bags) lbs just in case and also for future needs.

So I started adding adding the salt yesterday, stirred it up and checked the iAqualink salt reading and it was at 3100 ppm after only 12 bags (480 lbs). I knew it was concentrated at the bottom intake so I stopped there and let it stir overnight with the pumps on high. This morning it shows 2900 ppm, so a little dilution has happened overnight, but its still way off from my calcs.

I figure one of three things are going on. Either my pool is much smaller than I thought, which means I need to learn how to use a tape measure again (not too likely), or the iAqualink is giving a bad reading, or the pool was salty before I started (it was straight city hose water). I didn't bother testing for salt before I started adding bags because I assumed it would be zero from just adding city water.

Maybe my question is, how long should I expect full dilution to occur with the pumps running at 2750 rpm, the Dolphin stirring up the bottom, and brushing the salt all around. If I bought twice as much salt as needed thats ok, but I want to get the level steady before I turn on the SQG. Thanks in advance.

/Dave

 

[mknauss]

Welcome to the forum!

Your city water has salt in it. Probably 200-400 ppm. It is best to have a salt test kit before you start. The K1766 is best.

You should NOT power your SWCG on when adding salt. High salt content water can damage an operating SWCG. Always add salt, run the pump for 24 hours, then test salt, then start the SWCG.

It is not unusual for SWCG salinity reading to be off by 400 ppm or more.

If you do not have a salt test kit, you can take a sample of the water to a pool store for a salt test. Just do not buy any of the products they try to sell you.

If, this morning, your SWCG is operating (generating chlorine), then it is happy. I would not add any more salt at this time without more testing.

Hope that helps -- take care.

 

[Rancho Cost-a-Lotta]

I calculated ~32800 gallons, I was able to use a tape measure to get the deep end depth (used to be a diving board so its 9 feet) and entered my dimensions...

Did you use the average depth for the calculation? For example, if the shallow end is 3' and deep end is 9' your average depth for the calculation would be 6'. 32,800 gallons is a pretty big pool.

 

[kicksavedave]

Welcome to the forum!

Your city water has salt in it. Probably 200-400 ppm. It is best to have a salt test kit before you start. The K1766 is best.

You should NOT power your SWCG on when adding salt. High salt content water can damage an operating SWCG. Always add salt, run the pump for 24 hours, then test salt, then start the SWCG.

It is not unusual for SWCG salinity reading to be off by 400 ppm or more.

If you do not have a salt test kit, you can take a sample of the water to a pool store for a salt test. Just do not buy any of the products they try to sell you.

If, this morning, your SWCG is operating (generating chlorine), then it is happy. I would not add any more salt at this time without more testing.

Hope that helps -- take care.

I bought the TF-100 kit, but like a true noob I didn't get the salt test kit with it, so I'll do that now.

I haven't turned on the SWG and I won't until things are stable, 24 hours at least. I'm shooting for 3500 ppm, so I added two more bags, now its at 3100 again and I'll add bags two at a time and let it run for a while. Won't turn on the SWG, but it still tells me the salt levels (as best it can) even if its not generating chlorine yet.

- - - Updated - - -

Did you use the average depth for the calculation? For example, if the shallow end is 3' and deep end is 9' your average depth for the calculation would be 6'. 32,800 gallons is a pretty big pool.

I did use average depth but its a big steep deep end. I put the exact decimal length and width into Pool Math, but the average depth is always a best guess, if I use 5, 6 or 6.5 I still get a bigass pool.

 

[mknauss]

If your pool size is 30K plus, then your SWCG is undersized.

Be aware you will most likely need to run your pump and SWCG up to 18 hours per day at 100% setting in the summer months.

Use this for SWCG setting estimation SWG Run Time Calculator

Your SWCG can generate 1.25 lbs of chlorine per day.

Take care.

 

[kicksavedave]

If your pool size is 30K plus, then your SWCG is undersized.

Be aware you will most likely need to run your pump and SWCG up to 18 hours per day at 100% setting in the summer months.

Use this for SWCG setting estimation SWG Run Time Calculator

Your SWCG can generate 1.25 lbs of chlorine per day.

Take care.

Thanks for that link, I'll check it out. The PLC1400 is supposed to be rated to 40k gallons, but I am already expecting to need to run it a lot. I currently run the pumps 24 hrs on a lower setting, and when I get solar panels for my electric usage I'll dial it back so its not running during the peak hours, as you suggest likely 18 hours. Also, I have a PoolSafe cover which is closed whenever we're not using (or cleaning) the pool so that helps with evaporation and chlorine loss.

Funny thing is, it was at 2900 this morning so I added two bags. It went to 3100 almost immediately, but now three hours later is shows 3700. Guess I need that salt test kit sooner rather than later. Going to let it settle in before turning on the SWG, in no real rush.

And I guess I need a good accurate overnite FC Loss number as well. Will probably fluctuate a lot when the cover is open and people are swimming, vs when its closed.

 

[Rancho Cost-a-Lotta]

I've read on this forum that Pentair SWG salt readings may be inaccurate under 70 degrees. If your pool is not heated now, you're probably hovering right around there.

Edit: I just noticed you have a Jandy system. My comment may be irrelevant.

 

[mknauss]

The fact this pool will be covered most of the time will help your SWCG keep up. FC loss is decreased significantly if the cover prevents UV degradation of the FC.

You might put the cover detail in your signature -----

Take care.

 

[kicksavedave]

The fact this pool will be covered most of the time will help your SWCG keep up. FC loss is decreased significantly if the cover prevents UV degradation of the FC.

You might put the cover detail in your signature -----

Take care.

Done... Thanks

Sitting at 3700 ppm so far, which basically means it went from whatever it was to 3700 with 14 bags of salt. I'll get that test kit to see where I really am before I turn on the SWG.