Grey dust/powder

[jtucker615]

I've been scouring through the forums trying to figure out what I might be dealing with. I keep getting little piles of grey/brown powder/particles that collect in various areas around the bottom of my pool. A lot of other post suggest this is dead algae, but they also mention they have high combined chlorine. My combined chlorine is 0.

Everything is new in this pool. Sand filter, sand, pump and liner all replaced in Apr.
I test with Taylor k-2006 every other day and maintain the below levels My water is crystal clear. It is quite warm though at 91 degrees. I've been trying to figure out the best way to cool out back to like 84. Usually just myself and my wife swim 3-4 days a week.

FC -4 to 4.6 (20 to 23 drops)
CC 0 - colorless
PH 7.6
TA 90 (I know this is slightly high)
CH 120
CYA 35-40

I tested my phosphates using a powder test kit by Acuchek and it's 100 or less (the slightest bit of blue color)

I brush 3-4 times a week and vacuum to waste once a week. Backwash when my pressure rises 4-5 psi or weekly whichever comes first. Then rinse 20-30 seconds after.

I also use cal-hypo tablets in a floater.. I thought maybe it could be un-disolved tablet too, so I put a sock over the floater to limit the bigger particles in the water. The grey stuff continues to show up. I'm going to switch to liquid bleach for a week or two to see if that helps.

Is there any way of collecting a sample of this stuff to test? It dissipates as soon as I disturb the water near it. Any best guesses as to what it might be?

Also, I'm pretty sure the answer is yes , but is it OK to use chlorox bleach 7.25% sodium hypochlorite instead of pool store chlorine?

 

[JJ_Tex]

Your chlorine is below the target range, which is 5-7 for a CYA of 40. I'm guessing it is dead algae.

I would bump up your chlorine using liquid chlorine then do an OCLT and see if it is algae. Note the chlorine you posted is fine, as long as it is just plain old unscented, not splasless and not chlorox brand bleach.

Perform the Overnight FC Loss Test (OCLT)

The Overnight Chlorine Loss Test tells if the SLAM is finished or if you need to start a SLAM. This article says how to do the OCLT.

www.troublefreepool.com

 

[jtucker615]

Note the chlorine you posted is fine, as long as it is just plain old unscented, not splasless and not chlorox brand bleach

What's wrong with Chlorox brand? That's what I was told to use...unscented plain chlorox. Maybe I'll just go to the pool store and pay their high price for liquid chlorine

 

[Mdragger88]

I've been scouring through the forums trying to figure out what I might be dealing with. I keep getting little piles of grey/brown powder/particles that collect in various areas around the bottom of my pool. A lot of other post suggest this is dead algae, but they also mention they have high combined chlorine. My combined chlorine is 0.

You can have algae & still have 0 cc’s

Everything is new in this pool. Sand filter, sand, pump and liner all replaced in Apr.
I test with Taylor k-2006 every other day and maintain the below levels My water is crystal clear. It is quite warm though at 91 degrees. I've been trying to figure out the best way to cool out back to like 84. Usually just myself and my wife swim 3-4 days a week.

FC -4 to 4.6 (20 to 23 drops) 4ppm is very close to minimum for your cya - aim to maintain high target so you don’t risk falling below minimum ever FC/CYA Levels You can also use a 10ml sample & each drop counts as .5 ppm - this will conserve reagents & is plenty accurate.

For cooling the pool try a fountain.

CC 0 - colorless
PH 7.6
TA 90 (I know this is slightly high) if your ph is stable your ta is fine
CH 120
CYA 35-40 This counts as 40

I tested my phosphates using a powder test kit by Acuchek and it's 100 or less (the slightest bit of blue color)

I brush 3-4 times a week and vacuum to waste once a week. Backwash when my pressure rises 4-5 psi or weekly whichever comes first. Then rinse 20-30 seconds after.

Backwash when pressure rises 25% over clean pressure (whatever that is for you) until the sight glass is clear.
Be sure to rinse until theres no more sand in the sight glass.
Backwashing too often is actually counterproductive- the sand works better & captures more stuff when its a little dirty.

I also use cal-hypo tablets in a floater.. I thought maybe it could be un-disolved tablet too, so I put a sock over the floater to limit the bigger particles in the water. The grey stuff continues to show up. I'm going to switch to liquid bleach for a week or two to see if that helps.

Note that Cal hypo increases ch - low ch is not a problem in a vinyl pool, but too much ch is a problem that can only be resolved by water exchange.

Is there any way of collecting a sample of this stuff to test? It dissipates as soon as I disturb the water near it. Any best guesses as to what it might be?

You can attempt to vac with a skimmer sock to catch some.
Algae normally poofs & is slimy
Dirt/sand are gritty
Do an
Overnight Chlorine Loss Test to rule out algae

Also, I'm pretty sure the answer is yes , but is it OK to use chlorox bleach 7.25% sodium hypochlorite instead of pool store chlorine?

Actual clorox - no. It has Cloromax which are polymers. You don’t want that or anything that says fabric protection, splashless etc.
Walmart, lowes, Home Depot, menards & ace all have liquid chlorine for pools that is unadulterated.

 

[jtucker615]

Tried to upload a video...too big... the stuff looks gritty, but I can't pick it up between my fingers. Have to assume it's dead algae and not sand. I'll try the OCLT test.

 

[mknauss]

Post video to YouTube. Put link here.

 

[jtucker615]

Two vids of the stuff underwater

 

[mknauss]

Have to assume it's dead algae

I would agree.

 

[jtucker615]

Took my chlorine floater out of the pool at 7PM, took FC measurement at 8pm... I plan to test again at 7AM... pump is running

I'm curious. Everyone says you can use the 10ml sample and just count each drop as. 5, but I got a way lower measurement doing that than using the 25ml sample. Like .9 difference. How is the 10ml sample just as accurate?

 

[Mdragger88]

Consistency with the drops is key.
Hold the bottle completely vertical, don’t squeeze on the bottle, let them come out (about a drop per second). This makes for bigger drops.
If you squeeze the bottle to try to rush you end up with more drops & a higher count than actual.

 

[jtucker615]

Checked FC this morning before the sun hit the pool. No change at all...same exact reading from 8PM last night. I'm not sure what that tells me, because I still have grey matter all around.

 

[Mdragger88]

That’s great news on the oclt
A few days ago you listed cya of 50
Now it says 35 (which you should round up & count as 40 for chlorination purposes).
Pucks add cya so you’ll need to watch your cya & increase fc as needed to be sure you are following FC/CYA Levels
In these high uv summer days aim for high target so you don’t risk broaching minimum.
That’s probably what happened but it was corrected quickly.
Got anything in the pool that could be harboring funky stuff? Ladder? Light niche? Track around your steps?
Do you have sand in your sand filter or some kind of other media?

 

[jtucker615]

Got anything in the pool that could be harboring funky stuff? Ladder? Light niche? Track around your steps?
Do you have sand in your sand filter or some kind of other media?

Hey thanks for the response. On the CYA I'm not sure why it showed 50 that one day.... it's been consistent 35-40... I try to test it weekly... more lately since I'm getting used to the taylor test kit. I was going to go buy some dry stabilizer today to bring it up to 50. That's where some have suggested I should keep it.

I did bring my FC up to 6.4 yesterday and that's where it's at this morning. Still 0.0 CCs

No ladders in the pool, only stairs, which I vacuum. There is a light niche and the light is currently sitting on the deck as I'm trying to figure out if I wanna put a bulb on it. So I've vacuumed the niche...

I do have sand in the filter... the filter and sand were just replaced.

I'm just baffled...if it's not algae and it's not sand. I guess the only thing left is cal-hypo goo?

Going to switch to liquid chlorine today.. Next year plan to switch to salt.

 

[kellyfair]

In all my years of having a pool, I think I’ve had CC greater than O or .5 maybe once. I don’t even bother testing for it now, unless I’m at the end of a SLAM, which I’ve had to do 2 or 3 times over the years.

I think you should be SLAMing your pool, which means you don’t want to increase your CYA right now - it will just make you use more LC during your SLAM. SLAM chlorine level is higher than maintenance chlorine level, and it will kill whatever is lurking around in your pool. Once you see no more algae, at all, you do the overnight chlorine loss test OCLT), and if you pass that, the algae is gone, AND your CC is .5 or less, then your SLAM is over and you can raise your CYA.

SLAM Process

 

[Mdragger88]

Are the stairs removable ?

 

[jtucker615]

Are the stairs removable ?

No... not that I am aware of. I just bought the house and they look built in.

 

[Mdragger88]

No... not that I am aware of. I just bought the house and they look built in.

Be sure to check/scrub around the seams where they meet the liner.

 

[jtucker615]

Here's a positive... yesterday I took my floater out. Brushed the pool then tested the water and FC was 5.6... my wife, grandchild and myself swam for an hour or so then I shut the pump down for the night. Woke up this morning to FC 5.4 and almost no grey stuff.... fingers crossed its was only cal-hypo goo.... I bought a case of liquid chlorine too.... no more tabs if I can help it.

 

[Mdragger88]

Great
Aim to maintain high target for your cya to prevent broaching minimum at any time due to increased uv, bather load, whatever life throws. You can even go a scootch higher if you wish. It is safe for people, equipment & surfaces for fc to be anywhere between minimum & slam level for your cya.
FC/CYA Levels
If you need a little cya & fc you can use the pucks- just be mindful of their effects on cya & ph. Use PoolMath effects of adding.
Pucks have their place (little cya bump/vacation), but their blind daily use is a problem.
In the south, in the peak of summer you may need cya of up to 50ppm to help protect your fc from the sun.

 

[jtucker615]

Here's a positive... yesterday I took my floater out. Brushed the pool then tested the water and FC was 5.6... my wife, grandchild and myself swam for an hour or so then I shut the pump down for the night. Woke up this morning to FC 5.4 and almost no grey stuff.... fingers crossed its was only cal-hypo goo.... I bought a case of liquid chlorine too.... no more tabs if I can help it.

Spoke too soon... pump kicks on at 8AM...it's been running for 2 hours and the stuff is back... I'm now wondering is it coming from the sand filter and returns...it almost always concentrates in the same places on the bottom. Relatively near the returns.... the filter is brand new but could it have a bad gasket? Been installed wrong? How would I tell?