White Sediment at the bottom of the spa and pool

Yorker

Silver Supporter
Apr 22, 2017
426
Cathedral City, CA
A number of months ago I started noticing white sediment, residue build up in a couple corners of the spa/pool. It is not undissolved salt because I have not added any for a long, LONG time. My CH is really high (1000), but have been managing that with MA to keep my CSI somewhat stable. Could the white "stuff" be a result of the high CH? If so guess it's time to drain and refill.Pool Residue.jpg
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,368
Tucson, AZ
Try scooping some up with a turkey baster and letting it dry out on a paper towel. Transfer it to a small glass after it dries and add a few drops of MA. If it fizzles like soda, then it’s calcium carbonate scale. Happens a lot with SWGs when the CH is too high. Doesn’t matter what the CSI of the bulk pool is as the pH inside the cell when it’s generating chlorine gets very high.
 

Yorker

Silver Supporter
Apr 22, 2017
426
Cathedral City, CA
Thanks JN, I will have to wait a bit to scoop some up since I vacuumed this morning. Should only take a few days. I'll do the MA test and report back. Till then I have a couple questions. 1. What does "bulk pool" mean? 2. If it turns out to be calcium carbonate scale, is that a big problem to wait a couple months to drain the pool?
 

bmoreswim

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Jul 16, 2012
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Have you been able to grab some of your material for a test?

By bulk pool he meant the main body of water (not that which is inside the plumbing or equipment). For the short term, what is your current CSI? If it is calcium carbonate, you should inspect your cell to see if it is shedding all of the scale or if it is building up on it. If it is building up, then a 5-1 diluted water to MA bath is in order to keep it operating correctly. The inspection should take only a few minutes with a strap wrench.

And yes, you will have to periodically perform a partial drain to reduce your levels. Just part of the cycle for those with high CH fill water. No problem waiting until its safe. If you would see scale on the pool surface, then that would require quicker action of reducing CSI or draining/exchanging water (possibly using the tarp method if the ground is too wet or the sun too hot).
 
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Yorker

Silver Supporter
Apr 22, 2017
426
Cathedral City, CA
Here’s my update. Since my last post I discovered my CYA dramatically dropped from 60 to 30 in one month. I was under the impression that CYA only raised over time and only dropped if there was a lot of rain or a leak. After reading up on TFP I learned that high water temp’s can degrade CYA (we’ve had high 80’s and low 90’s).This possibly explains why I’ve needed to keep raising the production percentage on the SWG. In the last few days I now have the CYA to 70.

Yesterday I was able to collect a small amount of sediment, after drying I test it with a few drops of MA and it fizzled and foamed, just as JoyfulNoise thought (thanks JN).

After reading rmboreswim's post, I was reminded to check our salt cell. I was checking every 3 months and there was hardly any build up and pressure washing cleaned that out. The last time I checked was 5 months ago, so I went to check and there was a huge calcium buildup (see photos). I started with a pressure wash which helped some. Next a wooden toothpick and another pressure was got a little more off. The CSI is all over the place. it gets up to +3 or more, I knock it down to -.05 or -.1 and if a wait for 2 or 3 days it's back up to .3+

This was my first cell acid wash since the pool was completed over 2 yrs ago. I started with 5:1 then 4:1 (water/MA). Each time allowing it to soak for a couple minutes. Only a teeny tiny amount of bubbles were produced – not what I was expecting. Instead of subjecting the cell to longer exposure to the acid I dumped and rinsed it out and went back to the toothpick and pressure wash. A couple chunks were stuck between the cell blades, an extra long toothpick completed the job.

Lessons I've Learned:
1 - Check CYA more frequently in summer.
2 - Go back to checking the salt cell every three months (how lazy can I be, it’s less that two minutes)
3 - Be more diligent to keep my CSI under 0.

Questions:
1 - I use 14.5 MA. What dilution should I have used to get a proper foaming reaction when cleaning the salt cell with that much buildup?

2 - Why am I seeing that brown stuff getting in the salt cell. How is it getting past the skimmer, pump and filter?

3 - To keep my CSI under zero, I will need to add at least 16oz every day. Will this eventually lower over time. Does our 1200+ CH factor in this? (CH of our fill water 320).

4 - We seldom get any sand and very few leaves or debris in the pool. For a while now we mostly only brush and vacuum the pool once a week. How ashamed should we be? (I hope not to be kicked out of the club:)

Thanks again for your time - York
 

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mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
33,301
Laughlin, NV
At 1200 ppm CH, it is time for new water. So start planning a full drain and refill once fall gets here. Or check into Reverse Osmosis services if you would rather do that.

Do you have a water softener for your home?
 

Yorker

Silver Supporter
Apr 22, 2017
426
Cathedral City, CA
Hey Marty!

I'm planning on a refill in late September when the weather cools down. I have been wondering if a water softener might help. Maybe it's time to start researching. Is there any downside with using softened water for the pool?
 

mgtfp

Bronze Supporter
Mar 5, 2020
478
Melbourne, Australia
1 - I use 10.5 MA. What dilution should I have used to get a proper foaming reaction when cleaning the salt cell with that much buildup?
Do you mean 10.5% HCl concentration? Sounds a bit unusual, usually full strength MA comes in 31% and half strength in 15%.

My MA here in Australia comes in 34%. To clean the cell I use a 1:10 dilution which works fine for me. If yours really was 10.5%, then the equivalent would be about 1:3. If it's 15%, then 1:5 should be about right. Does your manual mention anything? That's where I got my 1:10 dilution from.
 

Yorker

Silver Supporter
Apr 22, 2017
426
Cathedral City, CA
Doh! Your are correct, it's 14.5% MA, and of course I did not think to ck the salt cell manual... that will be next on my list today. Thanks mgtfp!

... After reading the manual, it says one quart MA to one gallon of water — just how much do they think the cell holds, ours holds about than 25 ounces!

So it's 1:4 MA/Water, however they do not specify the strength of MA, I'm imagine they are thinking 31%. So I guess that means 1:2 if the MA is 14.5. I'll search TFP about that and see what's out there.
 
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mknauss

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May 3, 2014
33,301
Laughlin, NV
Is there any downside with using softened water for the pool?
As long as you be sure to start with non softened water, your CH will be fine. You will still have to manage pH and TA as the softener does nothing for them
Do you have a softener for your home?
 

Yorker

Silver Supporter
Apr 22, 2017
426
Cathedral City, CA
We do not have a softener for the house. What I was thinking was to add one for the house, and tap it into the auto fill, and perhaps a dedicated hose bib reserved for filling the pool. When you say "be sure to start with non softened water" do you mean NOT to fill the pool with softened water?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
33,301
Laughlin, NV
Right, Your base fill water has a CH of 250 ppm plus. If you drain the pool, then refill with that water, you start with a CH of 250 ppm, pretty good for a plaster pool. Then you would use softened water for fill water to make up for evaporation.

I am planning to install a water softener just for the pool. We do not have real issues in the house, but with our high evaporation rates we have to replace the water in the pool every 16 months or so. So with the water softener, we should get my with keeping the water a lot longer. Not real economic as our water is still cheap. But easier in the long run to manage.
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
7,176
Central California
I can vouch for the softener. Fill is 350. Pool is 375 after two years with softener. I have threads about my adventures. How my pool was destroyed by high CH (pre-softener). Another details how I connected the softener. One about lowering CH with rain water. It's a whole series. Riveting, really. But not yet available on audiobooks... ;) You get the first one for free, then subsequent adventures for only... well, actually, they're all free...
 

Yorker

Silver Supporter
Apr 22, 2017
426
Cathedral City, CA
I can vouch for the softener. Fill is 350. Pool is 375 after two years with softener. I have threads about my adventures. How my pool was destroyed by high CH (pre-softener). Another details how I connected the softener. One about lowering CH with rain water. It's a whole series. Riveting, really. But not yet available on audiobooks... ;) You get the first one for free, then subsequent adventures for only... well, actually, they're all free...
DIRK!!! I still remember all the help and guidance you provided me during our build (and the subsaquent chipout and replaster :). It's been a long time since I've had the pleasure to see your dolphin gliding in the water. I have today's reading material laid out for me now. Your adventures are EPIC!! - York

Water softener connected to auto fill, and new plaster start up
NuBee memory lane... Dirk (circa 2017) It's going to be a good day.
 
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Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
7,176
Central California
Yorker! Yo!! Sorry, I lose track of the many threads and their owners. Glad to see you're still around. Did I try to sell you the softener once before!?! Let me know if you need any other info. Mine is working great.
 

Yorker

Silver Supporter
Apr 22, 2017
426
Cathedral City, CA
Glad to see you're still around. Did I try to sell you the softener once before!?!
I'm still around because of you, and enjoying my mile long daily swim as I gaze at my crystal blue water! Not sure if you tried to get me to add a softener, and if you did you should have tried A LOT harder :). But all in due time I say, and that time is now. I'm enjoying reading bout "Young Dirk" being all confused about starting his own testing in your "Water softener connected to auto fill.." thread. And I recall "Wiser Dirk" telling "Young York" that in no time I would be testing with confidence.

So back to adding a water softener to our house and to the auto fill. Not sure if you have a thread with photos — would videos, testimonials and awards be asking too much? Granted, I'm only on page 2 of 9 of your WSCTAF tread, maybe what I'm looking for is in there, if not is there another thread you'd recommend? I'm a big DIY'er, confident with sweating copper fittings.

Here's to old nubee's reconnecting. I knew you when... look at you now ... a TFP Guide. It was your destiny!
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
7,176
Central California
I have some pics here. Let me see if I can find them.

doo, doo, doo, doo, doo, doo, doo (to the tune of the Jeopardy "waiting" song)...

They're in that same thread. All the "articles" I was joking about are in the same one, now that I think about it. The rain-water experiment, too.

The pictures or text might explain some, but not all of this: when I connected softener to existing auto-fill line, I built a Y of sorts, to keep the original hard water line in the loop. I've got two valves to mix, soft with hard, and three back-flow preventers to keep the water going in only one direction, to the pool. I left the hard water line in for two reasons: in case I ever wanted to add a little, for CH balancing and for a second reason I didn't think of at the time (THAT's how smart I am, I think of things I haven't even thought of yet... no, that can't be right...). I had a house flood on me way back and since then never leave town without shutting the main valve for the house. My pool, and irrigation, come off the street before that valve, so they were never affected by my paranoia. Buh huh hut... the softener is on the house side of that valve, and I spaced that. Shut off the main, left for three days, and came back to a pool with just enough water to cover the skimmer. Whew. Got away with it. But now when I leave, I swap the water supply from softener to street so the auto-fill stays fed. Some things for you to think through...
 
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Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
7,176
Central California
You got it. I love how I wrote "And to further bring this thread to its logical conclusion..."

What does "to further bring" mean?!? Maybe something to do with the fact that I go on for another five pages after that!!! 🤪 The more you read, the further away the end is!!

Hope you find something useful...