Initial salt level seems high

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adauria

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May 27, 2010
7
Hi folks,

I'm new here and this is my first post. I just got a new fiberglass pool with an Autopilot Cubby SWG. I confirmed with the installer and independently with the manufacturer that the pool "capacity" is 12,800 gallons. According to the pool calculator and the manufacturer's instructions, 320 lbs of salt or so should have gotten me to about 3000 ppm. So indeed, I added 8 x 40 lbs bags of salt to the pool, stirred it up good, etc. It's been in there perhaps 7-10 days now or so.

The Cubby, however, was telling me that the concentration was 4100 ppm. Now it's telling me that it's at 4400 ppm. Should this happen with a new system? Is this common? Do I just need to calibrate it?

My fear is that I will fall below 2500 ppm but the unit will still think it's in the safe zone, but it in fact will be causing all the problems you get when salt goes below that level but the system doesn't stop producing salt.

I did just order the test strips (as well as the TF-100 kit). It sounds like the strips may not be the most accurate thing around, but at least it will tell me if I am nuts or something (I suppose a qualified psychologist would be better at this though).

Any ideas? Should I call Autopilot?

-Andrew
 
That all sounds normal. It is extremely common to have an initial salt level of anywhere from 300 to 1,500. You were towards the higher end of that range, but nothing unusual.

The AutoPilot unit should be just fine with the higher than required salt level, and it won't cause any other problems, so I would just leave it where it is and let it come down naturally over time.

The salt meter in the Cubby is very reliable, it can be off by a few hundred either way, but it is unusual for it to be way off. As a general rule, it is best to trust the salt level from the SWG. The test strips are often fine, but occasionally they are way off. And your salt reading right now seems very plausible.
 
If it's been running for 7-10 days after the adding of salt, it should have balanced out by now.
Does the water taste salty? Usually at 3500 ppm or higher, it taste salty enough to notice. Around 3,000 ppm, it's barely perceptible.

Was your pool filled at the same time as when the salt system was installed? Did your installer perhaps add bleach initially to "clear up the water" or to "shock" it? There may have been some salt added as a result of that.

IF the salinity is accurately reading the level at 4400 ppm, going from zero ppm salt to 4400 ppm salt = 8800 gallons. What model and manufacturer fiberglass pool do you have?
However, 14 x 30 x 3-6 = 14,175 gallons. You would lose some gallons from the rounded corners. Just how much though, is a guess.
 
Great feedback guys - thanks!! This is a very helpful forum.

My pool installer did shock it initially, but this was before the SWG was installed (several weeks). I didn't think he added salt at that time.

The pool is the Composite Pools Key Largo. No idea what the model number is, but I doubled checked with the manufacturer and they told me 12,800 gallons.

It does taste somewhat salty though.

I got my test strips today, so I will give it a shot this weekend and get back.

-Andrew
 
Looks like the test strips also indicate something in the low 4000's. My Cubby is also reading back down to 4200. So, if we assume that the consensus between the SWG and the test strips (plus the taste of the water) adds some support to the idea that my pool is actually at 4200 ppm of salt, give or take, then I am left with the conclusion that my pool is not 12,800 gallons. I did double check this figure with the manufacturer though. And I double checked that I added 8 x 40 lb bags of salt, which - let's assume math still works the way I expect - is 320 lbs. According to the pool calculator, that would make my pool 9100 gallons or so.

I find it hard to believe that either:

1) my SWG and test strips indicate the same wrong number
2) my manufacturer has miscalculated the pool volume or is misrepresenting real world volume
3) 8 x 40 doesn't equal 320
4) pool calculator and the documentation were both wrong in suggesting 320 lbs for 12800 gallons of water to get to 3000 ppm of salt

So where does that leave me? Maybe there was some salt in the water initially... can't figure how though. It came from hoses using the normal water we use throughout the house. So, I am good and confused. But in any case, everything seems to be working well so I can't really complain.

-Andrew
 
There was absolutely for certain some salt in the water before you added any. The initial salt level may not have been 1,200, but it wasn't zero either.

Also, both of the salt tests you have tried, the SWG and the test strips, are +-400, so the actual salt level could be noticeably below 4,200.

Also, volume estimates are always estimates, they are never exact. A difference in water depth of a couple of inches can make a fairly large difference. The water level will change over time, so you never know exactly how much water you are dealing with at any given moment. And there is no reason to believe that the builders volume estimate was especially precise to begin with.

Also, the salt bags never contain exactly 40 lbs of salt. Sometimes they have more, sometimes they have less. Usually they are a couple of percent over.

There is really nothing surprising going on here. All the numbers you work with are going to be approximate and so nothing is going to come out exactly the way it was calculated. The error came out a little larger than you really want this time, but no harm done.

Over time you can refine the estimate of the pool volume. Watch some other numbers and see if they also come out higher than expected. If so, lower your volume estimate.

Likewise, it is always a good idea to add less of a chemical than you think you need, give it time to mix in, test again, and then adjust further from there.
 
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