White mold or calcium precipitate?

[salinda]

Hi all! I have floating, snowy, flakey looking white stuff in my pool and spa, but more in my spa. It settles in drifts in the spa. I vacuum it out with the PoolBuster, but I can't get it all.

For a year now, I have assumed that it is some sort of calcium precipitate. My water is clean and clear otherwise and no algae problems at all. I test with Ben's kit and normally only have to control for ph with my swg running. I do have pretty high Calcium readings of 520.

Could it actually be white mold? Is there some way to analyze the stuff I get out of the PoolBuster to verify?

[chem geek]

Is there some way to analyze the stuff I get out of the PoolBuster to verify?

If you add a little acid to a pool/spa water sample with this stuff in it and if the stuff dissolves, then it is likely to be calcium carbonate. I don't think that mold will "dissolve" with a little acid (to get the pH down to 7.0 or below -- no need to go below 6.5).

However, even with high calcium readings of 520, your TA would also have to be very high in order to precipitate calcium carbonate. Your TA would probably have to be well above 200. Also, I would think that your water would be cloudy as well. So I'm thinking that this isn't calcium carbonate. Let us know what happens with the experimental test.

Richard

[salinda]

My TA recently had to be increased from 70 to 90. Maybe there is high TA right at the swg cell or something?

As far as the white mold, what doesn't make sense is that I have never run biguinide in the pool and I don't think any of the previous owners did either. Maybe it is related to the solar fish I use to cut down on evaporative heat loss...I guess I'll just continue to vacuum the stuff out.

[CallMeIshmael]

As far as the white mold, what doesn't make sense is that I have never run biguinide in the pool and I don't think any of the previous owners did either. Maybe it is related to the solar fish I use to cut down on evaporative heat loss...I guess I'll just continue to vacuum the stuff out.

Hey Salinda,
I remember looking into those solar fish when I was researching pool solar & they popped up in the results. Isn't there a potential issue with residue or deposits that may result from using the solar fish? OK, I just searched on it again & here it is...
From PoolCenter's page on the Fish:

"TROPICAL FISH TM Liquid Solar Blanket ~ If the pool temperature is below 21o (70o) or there is too much Liquid Blanket in the pool, you may see a white residue, because the active ingredient has not dispersed evenly over the pool surface. This will go away by itself as the Liquid Blanket biodegrades over a few days and is not a problem. "

Does this fit your situation?

[salinda]

It doesn't really fit my situation. I live in Northern California and this was going on even in the heat wave when the water temps were in the 90's. My water temps are now "cool" from the high 70's in the morning to the low 80's after the solar has worked for a few hours.

The only thing is that our air temperature does regularly drop below 70 at night (although it didn't during the heat wave). Maybe the spa gets cooler at night since it is such a smaller body of water. Maybe I will call the Tropical Fish people and check, but I thought this residue is a white film that floats.