white powder

[apex]

As the title says, I am getting a whitish powder on the bottom of the pool. It collects by the steps and other areas and it looks like undesolved salt. The pool is 4-5 years old with a water change about 2 years ago. I am using the Goldline aqua plus system. I believe it is causing my cell to build up with scale and thus throwing my salt levels off (low). Any ideas what it is?

Thanks

 

[zea3]

Can you post a complete set of test results? That will help us know what to look at first.

 

[Guest]

The white flakes are actually from your salt cell!

 

[dmanb2b]

Welcome to TFP It very well can be calcium scaling, especially if you have high CH and high PH...Post a set of test results, otherwise our guess is as good as yours

 

[apex]

Here are the results from Leslies:
FAC 0
TAC 0
Salt 3600
CYA 20
TA 100
pH 7.8
Pho 200

They did not measure the calcium but they believe it is very high and are recomending draining the pool. I know we have very hard water in AZ but after 2-3 years seems a little excesive to me. I have added 2 pounds of shock and am deciding if I am going to add stabilizer or wait to see if I refill the pool.

Will the high Ca+ cause the build up on the cell? I checked it and it needed cleaning again after only 3-4 weeks.

 

[JasonLion]

Yes, a high CH level will cause calcium to build up on the SWG cell, unless you compensate for it by lowering your PH and TA levels and keeping them low.

 

[zea3]

[rant]They should test your calcium! Even if it is high and needs draining, if you have high calcium in your fill water what good will that do? Plus you won't know how much to drain without a starting number.[/rant]

What do you use to shock your pool? Also, what kind of filter do you have?

 

[apex]

I used the 1 pound bag of chlor-brite from Leslies for my shock. They basically said I should drain the entire pool so they were not concerned about a starting number. I have the Hayward cartridge (425sqft) filter.

This brings up another question; shouldn't the super shock of the SWG been sufficent without the need for "external" shock?

 

[zea3]

SWGs are great for maintaining chlorine, but they do not produce it fast enough to keep up with the chlorine demand a shock process requires. Also since your CYA is very low, most of your chlorine produced is burning off at an accelerated rate.

Chlor-bright is dichlor with CYA added. You can use that for now since your CYA is very low. For pools with SWG 60-70ppm is the recommended CYA level.

As far as draining and refilling your pool goes, unless you plan to have softer water delivered to refill the pool, we need to know how much calcium is in your tap water and how much is in your pool before you drain and refill. If you have not used a lot of calcium hypochlorite (such as power powder plus) which increases the calcium in your pool, draining and filling with tap water may not make a whole lot of difference, and I don't want to see you waste your money and time.

It is possible to manage a pool with higher calcium levels if you are diligent. By lowering your TA to around 70 and your pH to around 7.2 and keeping them there you can keep the calcium in solution so it doesn't deposit scale on your pool surfaces. There is a point where calcium is unmanageable and water replacement is required, but we won't know if that applies to you until we see how high your calcium is.

Should your calcium be at the unmanageable stage, you can see if there is a reverse osmosis service for pools available in your area. They can process your existing water and drop the calcium levels significantly. Otherwise your other choice is to drain and refill. If you choose to do this be sure and test the calcium of the replacement water first unless you have softer water trucked in for your refill.

Your cell is in a micro-environment inside the SWG housing. Since SWGs tend to drive pH up and you already have suspected high calcium levels, the micro-environment inside the SWG is a breeding ground for scale. Lower the pH and the TA and that should help with the scale on your cell.

Please go to the user control panel button underneath the TFP logo and add your pool's information to your signature. We need to know the pool volume in gallons, pool type (in ground, above ground), finish (plaster, or vinyl liner), pump brand and size, filter brand and type. It will help us remember specifics about your pool when we make recommendations.

 

[PoolGuyNJ]

Some parts of AZ have a service truck with a reverse osmosis machine for hire. This removes calcium and CYA and most everything else in the water. This would fit your needs exactly.

Scott

 

[PoolGuyNJ]

Oh, and if you have a DE filter, it could be DE due to a malfunction.

Scott

 

[apex]

Thanks for all of the help.

My signature has been updated with the details of my pool.

I will have to look into the cost of a soft water fill. I imagine it is very pricy. I am sure the Ca+ in our tap water is high but nothing compared to the constant evaporation and refill that goes on in our AZ summers.

PoolguyNJ, you wouldn't happen to have a name or number of that service would you? I put in the SWG to make the water better for my kids who have sensitive skin and that idea appeals to me but I wonder how long it would take for all of the soft water to evaperate and i am left with the normal tap water.

 

[zea3]

You can check out the Calsawayweb page and see if they are in your area.

 

[Poolsean]

First, it take a very high concentration of salt for there to be undissolved salts. If you can collect the white powder, put it in a cup (not styrofoam) with some water, then add some muriatic acid. If it bubbles up and dissolves, it's calcium based. If not, it may be silica based.
Second, Water Balance is most important, and not any one parameter moreso than another.
Third, calcium hardness in Arizona usually comes out of the tap at around 150 - 200 ppm. Not high at all. However, due to the amount of evporation, your make up water is continually adding more calcium hardness, so that over time, your calcium hardness level rises to very high levels. Using the Saturation Index as your guideline, adjust your Total Alkalinity and pH levels to compensate for high Calcium Hardness levels.
Fourth, while the comment was made that it does not "keep up with the chlorine demand a shock process requires", it may not generate a breakpoint or superchlorination residual level IN THE POOL, but is certainly able to maintaining chlorine levels and do a great job at controlling chloramine levels, in most situations. And in some conditions, the BOOST cycle is enough to clear up a pool after a pool party.
Finally, to the OP, the white powder may be as a result of very high TDS, total dissolved solids.