Chalky Residue

[E_Kansas]

I'm trying to figure out a situation I haven't had before. I'll briefly describe and if someone has more questions before you can give a good answer just ask. I've been SLAMMING my pool since Friday Afternoon - we were starting to eat through about 6 points of chlorine every day and had some cloudy "puffing" on the bottom when I'd sweep the pool - so I figured something was getting started in the pool even tho the water was still clear (except when I'd sweep).

We have a lot of iron in our well water - but most of it seems to have oxidized with the chlorine and I've filtered a lot of chocolate colored water when I back wash -- that's actually gotten a lot better since I filled the pool a couple weeks ago.

In today's test my PH was 8 and my TA was 250. I added 6 cups of acid 3 hours ago (based on the dose recommended in Pool Math).

What I'm noticing that I haven't had any other years is a chalky slightly / rough residue on my vacuum hose and the handle on my vacuum attachment. It's like there's a little film accumulating on them. I can feel it on the plastic vacuum hose attachment that goes in my Hayward skimmer basket as well.

Like, I said I haven't had this previous years and didn't notice it this year till about 3 days ago. (Pool has only been running for about 3 weeks now.)

I don't know whether it matters or how do deal with it if it does matter - since I don't know what's causing it.

 

[mknauss]

Can you post a full set of test results?

Be careful of testing pH if you are doing the SLAM Process. If FC is above 10 ppm, the pH test is invalid.

 

[E_Kansas]

Just now:

FC 14.5 (added bleach to bring up to 18)
CYA 40
PH 7.2
TA 230
CH 240

It seems like it is eating a lot of chlorine. (I've used a 1 1/2 gallons of 10% in the last 24 hours). I'll attach a picture of the "stuff" on the handle. Plus there is some spots on the bottom of the pool - they look brown. They don't want to sweep up like stuff on the bottom usually does. I've been vacuuming the bottom 3 times a day since Friday.

 

[mknauss]

Is that pH test from just now or before you started the SLAM?

If you can get a sample of the 'stuff', see if acid makes it fizz. Your CH is not high but if that TA is real you could have some calcium scale being created.

Best to just focus on the SLAM, complete that, and then deal with the other issues.

 

[E_Kansas]

Oh. I forgot to post CC
.5 or less -- on a 10ml sample I could just barely detect a pinkish color and one drop of the 0871 easily cleared it back up.

You may question this test My R003 is two years old. If you think that makes the test bogus let me know.

 

[E_Kansas]

Is that pH test from just now or before you started the SLAM?

If you can get a sample of the 'stuff', see if acid makes it fizz. Your CH is not high but if that TA is real you could have some calcium scale being created.

Best to just focus on the SLAM, complete that, and then deal with the other issues.

That is from now - during the SLAM.

 

[mknauss]

CC does not matter at this point, only at the end of the SLAM Process
pH test that low with high FC. OK -- with your high TA it will not be an issue.

 

[E_Kansas]

Here's an update.
CYA 35-40 (I did another test to reassure myself)
FC 18

According to the app my SLAM target is 16 with a CYA of 40. So I've been dosing to 18 to give some room for burnout. I think we dipped below slam briefly this afternoon - it dropped to 14 sometime between 3:30 and 6 PM.

There are little brown patches on the pool floor. They don't want to vacuum (and I've taken the vacuum attachment and felt underwater to be sure it has good suction) BUT they will puff to the sides if I move my vacuum attachment quickly across the bottom of the pool.

I took one of the plastic pieces from my Hayward skimmer basket that had the chalky residue and poured a little acid on it. It did fizz.

We've had issues other years that required a slam - especially if we've left on vacation. But none of them resulted in this "stuff."

I'll attach another picture of some of the residue I rubbed off from the skimmer basket. It's a powdery something that I assume is the same stuff collecting on the pool floor.

Is patience with the SLAM the prescription or do I have something else going on that I need to address?

 

[mknauss]

Patience. No reason to go above SLAM level FC. Just a waste of chlorine and potentially damaging to pool surfaces.

Odd you have calcium scale with those water conditions. After the SLAM, I would suggest keeping a lower pH for awhile to see if it goes back into solution.

 

[E_Kansas]

Here's an update. We've been slamming the pool since last Friday (one week). There really is not a noticeable change.

Overnight I lost 3 points of chlorine and the test showed 1 part combined chlorine.

I don't know what you need to know to give some advice. I've been testing 4-6 times per day. The SLAM level for my pool is 16.
I'm just thinking out loud here to see if anything gives a clue. I have backwashed the filter maybe 4 times this last week. It doesn't seem particularly bad. The water is crystal clear but at the bottom are little areas of something brown or rust colored. When I vacuum it doesn't seem to make much difference - and I have checked my vacuum attachment to see if it has suction. I think I have normal flow of volume through my filter.

One thing I thought of that may have a bearing on my target levels is that my pool volume is 7600 gal when I have it completely full. It often runs a several inches low. I assume this could make the CYA higher, right? (Compared to full.) But I have taken two tests - one of them with new reagent bought a couple weeks ago and I'm coming up with 35 (I can still see the little dot at 40, but it disappears before I get to 30). So I set my level at 40 in the pool math app.

I've been vacuuming twice a day for a week. I cannot figure out what the "stuff" is on the bottom of the pool. What could be settling down there that doesn't want to vacuum but if I push the attachment quickly across the floor it will swirl and puff to the sides.

I have nothing to defend. I think I must be missing something or doing something wrong.

If any pictures would help just ask.

 

[mknauss]

When I vacuum it doesn't seem to make much difference

Do you not vacuum up the 'brown or rust colored' material?

If you are losing FC overnight, the chlorine is killing organics in your system.

 

[E_Kansas]

I try to vacuum the stuff that has settled. But it doesn't. I cannot figure that out. I can pause with the vacuum attachment right over the spot or move it very slowly and it just stays there. If there are any bugs or anything else on the bottom it get those tho.

It's like whatever it is just sits there. But will move when I agitate the water by pushing the attachment more quickly.

I can agree if there is overnight loss something is getting killed. But what and why so long? Is it reasonable to expect a deal like this to take more than a week to clear up? The water never has been cloudy during this process - I started the SLAM intending to eliminate whatever is on the bottom of the pool. And a week later it looks just like it did.

 

[mknauss]

The material moves, but the vac will not pick it up. Can you get in the pool and get a sample of it?

Normal SLAM is at least a week to 10 days.

It is your pool. If you feel you no longer need to follow the process, don't. But the OCLT FC loss tells you something is in the pool water. Have you checked every fold, nook, cranny, skimmer, weir door, etc for algae?