Weird Blue Stuff in Sand Filter

[tylerhunt]

We recently bought a house with an in-ground vinyl pool. Been working on getting the levels right for a few weeks, but this afternoon after adding about 8 lbs. of borax (pH is currently < 7), I noticed some cloudiness in the water. After doing some research here on the sand filter and seeing Smykowski's tutorial on deep cleaning, I decided to open up the filter and see what I could see.

The previous owner told me the sand had recently been replaced (and there's a pile of sand around a nearby tree that indicates it was), but he had a pool guy do it, and based on some other things I've seen and some of the measurements, I don't have much faith in his guy.

Anyways, when I opened up the filter, the water at the top seemed to have a bluish tint with a bunch of particles floating around in it.



I proceeded to put more water into the filter, but it really wasn't clearing up much. I stuck my hand in, and pulled out some chunks of greenish-blue stuff from the surface of the sand.



We've been dealing with what seems like a high copper level based on anecdotal evidence of our girls' hair turning green, so this is where my mind when first when I saw this. I used the hose to syphon out as much water from the top as I could, which revealed this concentrated blueness on top of the sand.



The sand level was also much lower than I expected it to be. This is my first experience with a sand filter, but I guess based on the photos from the tutorial, I thought the sand would be nearly to the top of the standpipe. With the water drained out, I scooped out what chunks I could with my hand given the tight clearance and the depth of the sand. Here are a couple more photos of the kinds of stuff I was pulling out.




Once I reassembled everything, I was able to backwash and see the bluish water through the sight glass. I ran it until it started to look clear.

Any ideas on what this could be? Is it just dead algae or is this more evidence of a high level of copper present? I bought some Clorox Scale, Metal & Stain Control at Walmart today because it was the only thing I could find there that seemed like it might help. I haven't added it yet, since I'm trying to get the pH and FC at decent levels first.

Here are the numbers from this afternoon:

FC: 4.5 (it was 0.5 before I added a gallon of 10% bleach today)
pH: < 7 (base demand was 6 drops if I remember right—10 drops before I added the 8 lbs. of borax today)
TA: 40
CH: 500–750 (still trying to figure out what "blue" means since it all seems like shades of purple)
CYA: 200 (I know this needs major adjustment; I did drain a bit of water the other day before we had some rain)

 

[mknauss]

Welcome to the forum!
That material is all copper. You need to remove that from the system.
What test kit do you have? If the chemistry results are correct, it would be best to drain this pool and start with fresh water. What kind of pool do you have?
I suggest you read ABC's of Pool Water Chemistry.

 

[YippeeSkippy]

Hey there Tyler, welcome to TFP

That is quite an unusual shade of sand. I'd venture to say "copper" too since you confirm your girls are now green haired.

The gunky sand may be clarifer? Not good for filters. It makes for sticky gunk.

Lets get some true chem pros in on this ... paging @JoyfulNoise paging @JamesW

Maddie

 

[notmycupoftea]

We've been dealing with what seems like a high copper level based on anecdotal evidence of our girls' hair turning green

Copper does this? I thought it was high chlorine levels alone. This occurs in my pool but I don't have any evidence of copper.

However, that does look like copper-never seen that much though. I might have missed it but did you change the sand or add more? I made the mistake once of when I changed the sand in my filter I didn't add enough and it was a hard lesson learned.

 

[mknauss]

Copper does this? I thought it was high chlorine levels alone.

Chlorine has nothing to do with green hair. That is copper.

 

[notmycupoftea]

Chlorine has nothing to do with green hair. That is copper.

Wow interesting, maybe I do have copper/metals in my pool? I haven't done much research on this and I don't mean to hijack the thread. I don't have any visible blue material in my sand filter but would it be beneficial to add some metal control/removal to my pool?

 

[mknauss]

If you have used any products with the word 'Blue' in their name you have likely added copper.

For copper, you drain the pool to remove it.

 

[Mdragger88]

Think of it like the Statue of Liberty
She is made of copper but now she is oxidized & has turned green.
When the copper in the water oxidizes (because chlorine & the sun are oxidizers)
you get green stuff like stains, hair, nails, & sometimes even the water.

 

[notmycupoftea]

I used to use Green-to-Blue when opening the pool in the spring all the time, among others I'm sure. I see there are sequestering agents (GLB Sequa-Sol) to add that claim to remove it. In your opinion/experience, waste of money?

Edit: I would like to add I fill mine with well water. I live in a high-iron source and have a Iron treatment as well as stabilizer system for my home. My hose would run through this as well but I'm sure its not 100% removing metals.

 

[JoyfulNoise]

Just by looking at it I would also guesstimate copper. But the previous owner may have also used zeo-sand (zeolite) in the filter which sometimes has a greenish tint to it (although it shouldn’t tint the water). When replacing regular sand with zeo, you use about half as much.
My suggestion - that filter needs to be torn down, cleaned and redone with regular sand. The pool water needs to be drain as much as possible to remove copper. Fooling around with sequestering agents is pointless.

 

[tylerhunt]

What test kit do you have? If the chemistry results are correct, it would be best to drain this pool and start with fresh water. What kind of pool do you have?

I'm using a Taylor K-2006C. Do you think I should drain it completely or just enough to try to bring the levels down?

I might have missed it but did you change the sand or add more? I made the mistake once of when I changed the sand in my filter I didn't add enough and it was a hard lesson learned.

I didn't change it, but the previous owner claimed that the sand had just been changed. After seeing for myself inside the filter, I'm wondering if they didn't just removed to the top layer of sand instead of changing it all out.

Is there a particular height the sand should reach inside the filter? The specs on the filter (which is a Hayward—not sure what model) indicate an amount of sand by weight.

But the previous owner may have also used zeo-sand (zeolite) in the filter which sometimes has a greenish tint to it (although it shouldn’t tint the water). When replacing regular sand with zeo, you use about half as much.
My suggestion - that filter needs to be torn down, cleaned and redone with regular sand. The pool water needs to be drain as much as possible to remove copper. Fooling around with sequestering agents is pointless.

I'm pretty sure it's just plain sand below that layer of blue stuff, which just seemed to be on top of the sand.

We have a pool heater, too, which was used briefly after we first moved in. Is this a likely source of where all the copper came from? I'm wondering if the low pH may have been leaching copper from inside the heater, although I haven't checked to see if it even has a copper heat exchanger—I'm just assuming it probably does. I also noticed a small leak coming from the heater, so now that has me thinking maybe enough of it leached to actually put a hole in it. The heater has a bypass, but the previous owner also ran the water through it all year long, even when the heater wasn't being used.

Appreciate all the advice. What I'm hearing is that I should replace the sand in the sand filter and replace all/most of the water in the pool. Sounds like I have my work cut out for me, but that at least confirms my suspicions. Thanks!

 

[mknauss]

Low pH (below 7) will leach out the copper from the heat exchanger and destroy it. Have trichlor tablets/pucks been used in this pool? Is there a tablet chlorinator device?

 

[tylerhunt]

Have trichlor tablets/pucks been used in this pool? Is there a tablet chlorinator device?

There is a tablet chlorinator device. The previous owner relied on that for chlorine, but I've switched over to liquid since we took over about a month ago. I'll have to check when I get home to see what kind of tablets he was using.

 

[notmycupoftea]

Is there a particular height the sand should reach inside the filter? The specs on the filter (which is a Hayward—not sure what model) indicate an amount of sand by weight.

I inherited my current sand filter from the previous homeowner as well, its pretty much the only pool equipment I haven't replaced because it works just fine. But, I don't know the exact amount of lbs to put in mine either. I put enough in there to cover the incoming arm to the diffuser (top pvc pipe in the image below) and then some. I think sand is about $10/50lb bag and just guessing you'll prob use 4-5 bags just based on average sand filter sizes. I said it before, but if you don't add enough sand, or there isn't enough currently in there, you're gonna have a bad time. Your pool will never be clear.

 

[mknauss]

Be prepared to take the heater out of the circulation system. It sounds like it is compromised.

 

[JoyfulNoise]

Some people use “filter fiber” (cellulose fiber) as an additive to sand filters to improve filtration and when trying to do metal removal. The cellulose fiber can create a layer of “crud” on the top of the sand. If the previous owner was using lots of tabs and copper based algaecide, they may have used the filter fiber to try to trap metals along with a sequestering agent. Jack’s Magic product line as well as other manufacturers all have protocols for removing copper that involve sequestering chemicals and filtration aids. No way to know for sure since the previous owner used a pool service. Who knows what they were throwing into the pool water.

Honestly speaking, and I know it’s easier said than done, I’d highly recommend not only completely redoing the filter with clean sand but also drain the pool as much as you can tolerate. I’d rather start with a fresh slate than try to fix someone else’s mess.

 

[revitup]

Disintegrating pool toy/float?

 

[JamesW]

CH: 500–750 (still trying to figure out what "blue" means since it all seems like shades of purple)

You have a lot of copper in the water.

Do not trust the calcium test with this much copper as the copper will interfere with the test.

 

[tylerhunt]

Have trichlor tablets/pucks been used in this pool? Is there a tablet chlorinator device?

The tablets were trichlor.

Honestly speaking, and I know it’s easier said than done, I’d highly recommend not only completely redoing the filter with clean sand but also drain the pool as much as you can tolerate. I’d rather start with a fresh slate than try to fix someone else’s mess.

I hear you loud and clear. Draining and redoing the filter is now on my list of to-dos for the coming week. Thanks for the advice.

 

[JamesW]

What was the starting TA?