What do I have here? Algae? Sand? Salt?

[Alacayo22]

Hi guys,

I have this white substance that is really starting to get out of hand. It looks like salt and feels like sand. Maybe a little slimy when wet but i wouldnt describe it as gross. When its dry its very concentrated. No yellow/green in the pool that i can see just white. I mostly see it on the color tile where it settles. It does cloud up when i brush and makes the water cloudy/hard to see through. Otherwise the robot cleans the pool pretty well and i dont see any issues. Robot runs every morning and climbs up the walls to scrub. When i empty the basket (about every week) this substance is there. Today it was significant. I manually brush the pool about once a week but never more than two weeks.

Could be salt? I think its unlikely but i did add about a bag about a month ago. Chlorinator is also about 4 months old. Sand? We did our background less than 6 months ago and put turf. The installer put sand and said we would see some sand in the pool at first which we did. But now im seeing more of this white substance so i dont think its sand.

Here is my full panel from today using TF test kit:
FC - 18
PH - 8.2
TA: 90
CYA: 30
CH: 325
salt: 3000

I know the FC is high. I do tend to run it high since i dont want it to get low but this is too much. I am surprised CYA is so low. We had a ton of rain in the last 3-6 weeks with water overflow. I have stabilizer on hand ready to put in but might not be enough.

Pictures:

 

[Flying Tivo]

How much tile grout do you have? Since my pool is fully tiled, i get the same. At first a lot like you, now its much less. I see you have some type of aggregate. You can read up on the manufacturers if it has sand as a component. I compared it to a left over bag of grout and it was the same type of sand. Since the robot is doing the scrubbing that is where it will show up the most.

 

[Mdragger88]

That sure looks like sand.
Do you have a sand filter?

 

[Alacayo22]

How much tile grout do you have? Since my pool is fully tiled, i get the same. At first a lot like you, now its much less. I see you have some type of aggregate. You can read up on the manufacturers if it has sand as a component. I compared it to a left over bag of grout and it was the same type of sand. Since the robot is doing the scrubbing that is where it will show up the most.

Not sure how much grout I have. We redid the plaster about 5 months ago at the same time we put turf (including the sand with turf). The builder said we would have some material in the pool at first and we did. The robot would have some material but it was nothing like the above pictures. Over time the material became less and less until recently when the material has become excessive.

I also cleaned the filter and it was filled with this stuff. It took a long time to clean the filter. There was a good amount at the bottom of the filter tank too to flush out. Although I did not experience any filter pressure out of the ordinary, the only other hypothesis I could come up with is whether it's possible that the filter got clogged up enough with this stuff that there was some sort of backwash into the lines and into the pool?

That sure looks like sand.
Do you have a sand filter?

I have a cartridge filter which has been doing a normal job (I think).

 

[Texas Splash]

Since you said you've had a lot of rain, I would hope it's just sand from the turf project. If it were a calcium product, you could probably test it by making a pile and putting some acid on it. If it fizzles it's calcium, but I'm hoping just sand.

 

[Alacayo22]

Hi guys, bumping with an update & the mystery continues!

I finally got around to getting some more acid and did the suggested test. For reference, I grabbed the white substance from the vacuum basket and put it in a red plastic solo cup then poured some acid on it. There was some other junk from the vacuum so the white stuff wasn't pure but it was most of the stuff. Anyway, when I poured the acid it immediately starting fizzling a lot. I was like "holy Crud!!"

I started wondering if it could be dry stabilizer. I've been trying to get my CYA up since I keep getting a reading of about 30. I put about 1-2 lbs in a skimmer sock, tie the sock to the handle, and then let it float in the basket for about a day or two. When I come back the skimmer sock is usually empty. I'm now wondering if the dry stabilizer is dissolving enough to get through the sock but not dissolving in the water completely?

I did the CYA test when I did my original post above then added some stabilizer. Today I did a re-test and still got 30 at most. Since I was so unsure of myself I committed sin and went to Pinch a Penny for a test. They registered my CYA at 60 and everything else was fine.

So not sure if the substance & CYA are related or if its something else and the mystery continues.

Since you said you've had a lot of rain, I would hope it's just sand from the turf project. If it were a calcium product, you could probably test it by making a pile and putting some acid on it. If it fizzles it's calcium, but I'm hoping just sand.

 

[Mdragger88]

Cya is an acid - not sure it would fizz.
Sounds like calcium.

 

[Jimrahbe]

22,

It is calcium.. I get the same thing if I let my pH get out of hand..

The robot does a very good job of picking it up...

If you keep your CSI at -.1 to -.3 the problem will go away.

Thanks,

Jim R.