Sand-like residue from SWG?

[mbuckmaster]

New pool install, with a cartridge filter…yet every time I run it I get tan sand-like substance all along the bottom of the pool in the vinyl wrinkles. Vacuum it all up, clean the (brand new) filter, then run it again and more sand. The cycle continues on and on these past 3 weeks. Chlorine has never been below 11ppm and the water was trucked in clean and has always been clear as glass, so it can’t be algae, right? It’s gritty but not quite like actual sand; and with a cartridge filter there’s no sand to be had anyway. Is it some kind of byproduct of the SWCG?…I am still getting the balance right, so maybe some chemical reaction is happening there? I’ve read a few sites that say there can be some residue created by SWCGs, but not sure if that’s true. Thanks for any insights you can provide!

 

[Newdude]

What's your yard look like after the build ? Is it entirely cleaned up ?

 

[mbuckmaster]

No, waiting on deck to be installed so it’s all red clay. Maybe a little sand but we haven’t even been in the pool so it’s not us tracking it in…of course there’s sand under the liner, but I can’t believe it’s a leak or something, right?…

 

[Newdude]

there’s sand under the liner, but I can’t believe it’s a leak or something, right?…

That's all likely fine. I'll still guess it's environmental in some way.

To rule out algae we Overnight Chlorine Loss Test. If you lose FC overnight with no UV, then there's organics in there. I don't believe that's the case here but until you pass it, all we can do is guess.

We might still guess after you pass it, but we'll do so with alot less sense of urgency knowing a swamp isn't imminently on the horizon.

 

[proavia]

What test kit are you using?

Gather some of the sand like residue.
Post a pic of the residue.
Smear it on a white piece of paper. Did it smear?
put a drop of muriatic acid on it. Does is fiz?

 

[mbuckmaster]

Ok, thanks for the replies…update here. I’m using a Taylor K-2006C test kit. I did the overnight chlorine loss test, FC was 10ppm last night at 11pm and then 9ppm when I was able to test around 9:30am (swcg off all night and the last few days too…it peaked at 17ppm four days ago). CC is now at zero, or maybe 0.25 if I squint and see a little pink tint. CYA is at 60ppm, or maybe 70 (still getting used to reading that test accurately). Pool Math says everything else is in ideal ranges, pH at 7.6, TA at 80, CH at 130, and Salt at 3100. Interestingly, after a recent hard rain the salt dipped to 2700 and—without me adding any actual salt—has steadily risen the last four days to 3100.

I didn’t get an actual sample yet, as the temp is 76F and that’s a little chilly yet for me! Pool is in shade all day with only filtered sunlight for 2-3 hours, so we have a heat pump that works pretty much constantly. Had the sand before and after that was installed though, and again, it’s a brand new cartridge filter and pump, and the pool itself is just 3 weeks old since install. I did take a pic of the “sand” below, and will get in later today to get a sample to examine and try to smear. From what the robot picks up, though, it’s hard and silicate-like, doesn’t seem organic at a glance. But I’ll examine more closely later and update with more pics. Thanks again for the advice and wisdom!

 

[mbuckmaster]

Temp for up to 78F so I sucked it up and scrambled in the pool to collect a sample of the sand-like substance. It proved difficult because—a ha!—it is not gritty nor hard, but soft and easily scatters when I tried to get her some. Ended up getting some with some water in a dropper and let it settle in a glass ramekin (pic below). Despite the 20 micron cartridge filter running non-stop the last 3-4 days, I’m guessing it’s just organic residue?…it seems like a lot for just leaves and dust/pollen, but then again the pool is under a canopy and gets plenty of leaves in it. TIA for any confirmations or other ideas of what this is for this aspiring newbie! =)

 

[proavia]

What happens if you spread it on a piece of white paper or a white paper plate?
What happens when you put a drop or two of muriatic acid on it?

 

[mbuckmaster]

Sorry, I can’t lift it out of the water to spread on paper…it’s too soft/liquidy. I don’t have any muriatic acid.

 

[proavia]

Sorry, I can’t lift it out of the water to spread on paper…it’s too soft/liquidy. I don’t have any muriatic acid.

Can you let it settle and then pour the water off. Might take a few times to get to the 'stuff'.

How are you adjusting pH?

 

[Newdude]

@kimkats would suggest a Turkey battery to suck up the crud for testing.

 

[proavia]

@kimkats would suggest a Turkey battery to suck up the crud for testing.

If I grabbed the turkey baster out of the kitchen and used it on anything pool or outside related, I'd never have to be concerned about the pool ever again.

 

[Rocket J Squirrel]

If I grabbed the turkey baster out of the kitchen and used it on anything pool or outside related, I'd never have to be concerned about the pool ever again.

I had to buy Mrs. Squirrel a new turkey baster. They're pretty cheap.

 

[Newdude]

had to buy Mrs. Squirrel a new turkey baster. They're pretty cheap.

+1. They have them at the dollar store. Or. That's why they invented dishwashers.

 

[kimkats]

Now, now, now..............every pool should it's own toothbrush and turkey baster...........just sayin.................A TOOTHBRUSH?? ??? yes for brushing around the small things like the returns and skimmer face.

For the turkey baster:
Suck up the stuff
Put a white paper towel in a strainer
squirt the pool water and stuff out onto the paper gently. Let it dry and show us what it looks like then.

 

[mbuckmaster]

Well I tried this but it poured out with the water. It’s just very aqueous. I’ll have to collect another sample. In the meantime can anyone definitely say if this is a byproduct of the SWCG or no? Or is it clearly organic and not an issue with the 3-week old equipment?

 

[BDY]

The only byproduct of a SWG should be chlorine, hydrogen and maybe calcium flakes if your chemistry is off and you are scaling the SWG.

 

[kellyfair]

If it isn’t dead algae, I’m voting for organic.

My soil is pretty sandy, and every time the yard is mowed i get debris in the pool.