Pool water looks a little bit like a snow globe....

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ejhutchens1

Member
Aug 25, 2019
11
Tucson, AZ, US
Pool Size
15600
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I'm new to the TFP forums. I haven't had much trouble with my salt water pool since it was put in about 2 years ago. We typically use our pool fairly lightly. The SWG has easily kept chlorine in range, and the only thing I've really had to do regularly is add a little bit of acid once a week to keep the pH down in the normal range (the pH will tend to drift high if left unattended for too long....). Our city water here in AZ is quite hard though and, over the last year, we have seen a slow increase in the appearance of white scale on the waterline tiles.

We had some family visiting last week who like to use the pool, and we decided to fire up the pool heater in order to get the water temperature a bit more comfortable. The pool water now looks a little bit like a snow globe! (A bit of an exaggeration perhaps, but not by much....). Flakes of a soft white material accumulating in the corners of the pool & also floating around in the water. I tried to net out some of this stuff, but this has proven to be a very time-intensive & ineffective removal method due to the quantity of the flaky material. The filter doesn't seem to taking this material out, probably because the flakes tend to slowly sink to the bottom --- and if I try to sweep the flakes toward the main circulation intake on the bottom of the pool, the flakes just stir-up into suspension in the water again and then slowly settle out elsewhere. I'm assuming that this new flaky phenomenon was triggered by my heating up the pool water. I'm sure this isn't a unique problem, but it's not a problem that I'm familiar with. I'm wondering if something more subtle than just basic water chemistry has gotten out of balance, and is causing the issue.

So my question would be --- what's the best solution to my issue? My thought process tells me I should find some way to get this flaky material back into solution in the pool water, then drain some (or all?) of the water out of the pool, and then refill (& restore normal salt concentration & water chemistry) in order to dilute the concentration of the offending material, which would hopefully prevent the material from reappearing. But I'm not really sure how I would accomplish this in practice --- or whether this idea would actually be the proper approach to solving the problem. It may be that someone has previously addressed this issue somewhere in the forums, but I was unable to locate it, likely because I don't know the official terminology for this phenomenon. Help?


Pool: Built in 2019, in-ground, saltwater, 15,600 gal, no spa, pebble finish. Cleaning system: Blue Square Q360, in-floor.
Pentair Equipment: IntelliFlo VSF Pump (3 hp) / CCP-420 cartridge filter / IC-40 SWG / MasterTemp 400 NG heater / BioShield UV
Easy Touch 8 Controller with ScreenLogic wireless interface.
Water Testing: Hach Aquacheck 7-Way Test Strips.
 
So, you need some real test results, with a proper test kit. I’m going to guess that you are dealing with calcium due to your hard water and imprecise chemistry. If you take a look at the test kit link in my signature, that is the one we recommend. Once we get some accurate test results, we can provide better assistance.

Just curious, is there scale on your salt cell?
 
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I just re-installed my salt cell about 2 weeks ago --- I had pulled it out for the winter (low water temperature) & had swapped-in the dummy cell. (I cleaned the salt cell with 4:1 acid solution back in November when I pulled it out; it had a few small areas of scale build-up, not bad.) I haven't re-checked the condition of the salt cell in the last few days, in the time since we heated up the pool and this flake situation suddenly worsened. Not sure if it makes any difference, but the pool water is still quite clear (not cloudy looking) even though all these flakes are present --- I can easily see to the pool bottom to observe the flake accumulation areas

Your point on the test kit / more accurate chemistry data is well-taken, but --- if possible, I'd really like to start getting this pool moving back in the right direction sooner rather than later. Even though it might not be the absolute best quality data, test strip data is still data that could be acted upon while I'm waiting around for an indeterminate period for a test kit to show up. Since the circulation/filtration system doesn't seem to be removing the flakes, I'm a bit nervous wondering where all of this material is eventually going to end up (and what damage it might cause) if I don't start taking some sensible & directionally-correct actions towards getting rid of it....
 
EJ,
What's basically being told to you is your method of testing is really not reliable at all. Test strips are at best guess strips. Order that TF-100 pro kit which includes the Taylor K-1766 salinity test along with the highly recommended speed stirer too. Once you get it we'd need a full set of numbers as follows
FC-
CC-
PH-
TA-
CH-
CYA-
SALT-
CSI-
From there we'll guide every step of the way to the perfect pool. In the meantime read pool school and ABC's of pool chemistry to have a better understanding when the guidance begins.
 
OK --- here are my pool water quality test results (using the TF-Pro Salt kit) :
FC = 3 ppm
CC = 0 ppm
PH = 7.5
TA = 70 ppm
CH = 900 ppm
CYA = 35 ppm
SALT = 3600 ppm

TEMP = 68 F
CSI = -0.01

Another piece of data that is probably worth knowing:
CH = 225 ppm -- for our fairly 'hard' city water system ( pool water supply )

When the white flakes started appearing/accumulating in our pool (a couple of weeks ago), we had been using the pool heater to bring the pool water temperature up into the 85-87 F range, so that houseguests could comfortably use the pool during their visit. The water temperature has now settled back down into maybe a 65-70 F daily range, and it seems like the flakes are no longer forming/accumulating. We were able to net out maybe 60% of the the "drifts" that had previously accumulated on the bottom of the pool, but this was very slow going. I have continued to try to push the remainder towards the center drain intake for the pool water circulation/filtration system, but the remaining flakes tend to stay suspended for quite awhile once they are stirred up, and typically will eventually just settle out again somewhere else on the pool bottom --- effectively thwarting my attempts to use the pool water filtration system to remove them.

If a higher water temperature will trigger this flake formation phenomenon, then I'm pretty sure that we are going to continue to have this problem going forward. When summer eventually sets in here in Tucson, our pool water temperature can sit in the 80+ F range for days on end. I'd like to know how I might tweak the pool chemistry to help prevent the flakes from appearing when the pool water temperature trends warmer. I'd also like to know if someone might have a suggestion for an easier/smarter way to more quickly get rid of the all the existing flakes that have remained in the pool.

Thanks,
Eric
 
I thank you greatly for adding the test results as it’s painting a clear photo. 👍 I’m gonna tag @mknauss on this thread as he’s got more experience on scale than do I.

I suspect you’re facing a drain/refill as the high calcium level in your water has caught up to you. I’m guessing that you see this slightly more as the pH increases and your temps get hotter. Two quick questions to assist us further,

1. When was your last drain/refill to lower the CH levels?

2. How do you chlorinate the water do you ever use CalHypo?
 
The warmer water raises the CSI, which in turn has the SWCG create scale easier. The polarity changes on the IC40 sheds scale in thin little pieces, which can float.

You will need to either tightly control your pH and TA to reduce your CSI with your high CH, plus consider adding borates to reduce the pH rise in the SWCG cell, or drain and refill the pool for a fresh batch of water. If you use your normally high CH fill water due to evaporation, you will be drain/refill about every 2 1/2 to 3 years.
 
Thanks for the responses Lee & Mark. Mark is *almost* :) spot-on with his assessment --- the only additional info would be:

1. The initial pool fill & start-up was in July 2019, but we had to completely drain & fill again in September 2019 due in order to allow a fix to a cosmetic issue with the pebble finish that we noticed after start-up. So... the last full drain of the pool was just over 1.5 years ago. We have not done any partial drains.

2. We do have a SWG, which I have been keeping installed in the circulation system from early March thru early November. In the colder Nov - Mar period, the pool water is mostly too cold for the SWG to work effectively, so I pull it out of the piping & replace it with a dummy cell (I was instructed that doing this would help prolong the lifespan of the SWG). During this period, I add liquid (10% sodium hypochlorite solution) to chlorinate. I would say that our pool rarely sees heavy use --- exceptions would be when family is visiting --- and a setting of 25% on the SWG seems to be adequate to hold target chlorine levels for our typical usage.

I suspect that you are correct about calcium being the culprit in the flake/scale formation. We spent a bunch of time attempting to net out the flakes over the last couple of weeks, but there may still be enough flakes left on the bottom of the pool to try the "acid test" on them to try to confirm their composition. I'll check on that later this morning. So far, with the heater off and the pool water being cooler again (65-70F), the flakes haven't been reforming. But I'm afraid that the flakes/scale are very likely to come back with a vengeance as the weather (& pool water temperature) continues to warm up here in Tucson.

The only other out-of-the-ordinary thing that I can recall doing, as far as maintenance goes, was a brief battle I tried to wage between Alkalinity & pH last summer (2020). I noticed the Alkalinity was getting a little on the low side, so I added some sodium bicarbonate (good old Arm & Hammer baking soda), which helped. But then the pH went higher than usual (it normally tends to slowly drift high in our salt pool anyway), so I added some acid --- and the Alkalinity went down again. I went back & forth with this for several days, probably ended up adding around 10 lbs of baking soda before I finally gave up on this see-saw battle. The Alkalinity seemed to be stable at the somewhat lower value, so I just decided to leave it alone. I don't know if my actions in this brief Alkalinity - pH battle might have played any role in the flake/scale formation.

Mark, were you suggesting some sort of 'external' water softener specifically designed for treating pool fill water? If so, I don't know a thing about these. We are planning to get a typical home water softener for the house tap water in the next few months, but my understanding of home softeners is that they are typically not able to easily put out the massive amounts of soft water that would be required to fill a pool in any reasonable amount of time. I can currently fill our pool with the harder city water in less than 30 hours using a garden hose --- I'd be concerned that it might take weeks (and tons of salt & many, many system regenerations) to be able to fill the pool with a water softener involved. There are companies here that will bring you tank trucks full of pre-treated water for pools, but it's quite expensive. I think it cost us about $150 in city water to refill our pool in Sept 2019, and my neighbor (who is currently in the process of putting in a pool) said that his research was indicating that trucked-in pool water would cost somewhere in the range of 5-10 times what I paid for the city water.

I'm looking forward to getting your specific advice on how best to proceed in reducing this flaking/scaling tendency in our pool.

Thanks, Eric.
 
ejhutchens1 said:
We are planning to get a typical home water softener for the house tap water
Click to expand...
You would not fill the pool after a drain with it as you need a CH of the pool water of around 300 ppm to protect the plaster. You would use softened water for make up water due to evaporation. I suspect that is about 50-60 gallons per day, give or take, in the summer. If there is any way to plumb in a line to your autofill from the softened water system, do it.

Your TA / pH battle was not necessary. Your TA (and pH) rises due to the addition of your high TA fill water. Aeration raises the pH. So when you add acid due to high pH, your TA comes back down. I find my TA balances around 70-80 ppm by adding acid when the pH reaches 7.8 or so and dropping it to 7.4. That works great until your CH gets to around 800 ppm. Then the scale issue starts to happen and you need to force the TA lower, say down to 60 or so. You do that by reducing your pH to 7.2 when it gets to 7.6 or so. It will take acid to maintain that.
 
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MKnauss, thanks for the response. I suspect that, once we get our home water softener, it might be relatively easy to plumb a softened water line to the pool auto-fill source. We have a pre-plumbed home softener location in the garage, and the pool auto-fill source is located just on the other side of a stucco-ed exterior wall.

The only reason that I got sucked into that Alk-pH battle was that, after many months of stability, the Alk appeared to have *dropped* 20-30 ppm out of nowhere. Of course I was using test strips for water quality checking back then --- perhaps I opened a new bottle of strips, and was getting a falsely lower Alk reading from that batch of strips? Who knows at this point...

The consensus I'm reading here so far here seems to be that I should consider draining some or all water from our pool --- but would I need to drain it completely? Could I get enough relief by partially draining & refilling? About how fast should we expect to see the CH increase naturally over time in our pool? Is there a recommended maximum CH which, when I see this result via water testing, should always trigger me to perform a drain/refill?

Just trying to get a little smarter about CH --- in our pool specifically, this seems to be the thing that is most likely to sneak up & bite me over enough time....
 
The issue with partial drain / refill, is math. Say you do a 1/4 of the pool volume. Your current CH is 900. So you would have 3/4 of pool volume with 900 ppm CH and you would fill the other 1/4 with 225 ppm fill water. So your result is a CH of 725. Not much effect.

If you had your water softener up and running, then you could do partial drain and refills. It will take alot more water, but it would reduce the CH more substantially.

Not sure what your cost of water is there, but a full drain and refill will make your life easier (and eliminate the snow globe effect).

If you continue to use the un-softened water, then you would need to drain/refill in about the same time frame you just saw. Around 2 years. You could do partial drain refill when it gets to say 500 ppm or so, especially if you have softened water (but do not have it plumbed to the autofill).
 
OK, so could you walk me thru the specific steps I would need to take to do a drain/refill, and then restore the recommended pool water quality?

I would guess that the basic steps would be:

1. Use our pool circulation pump/system to drain out some (or all) of the pool water --- drain as much as necessary to bring the CH down to the desired starting level.
Time required for this step would be ??? hours --- I can't seem to find the rated flow for my circ pump in the documentation.
If draining out all the water, seems like I might have to use caution & close observation at the end to avoid running the pump & system dry?
Any concerns about drying out of the pebble/plaster surfaces during the draining & refilling period?

2. Refill the pool with city water (appx. CH = 225) using a garden hose.
Time required for this step would be about 28 hours (if the pool was completely emptied) based on previous fills.

3. Once pool is full, test the water & restore water chemistry to recommended levels. This is where I'll need some help.
Before I start the process, it would be good to re-validate with you the generally recommended water quality test results for my saltwater pool.
Also, it would be good to know exactly which chemicals I would likely need, and approximately how much of each chemical.
I assume I would need quantities of pool salt, muriatic acid, CYA, maybe some liquid chlorine? (to get initial CL levels up before activating the SWG).
Am I likely to need baking soda (for increasing TA) ? Am I likely to need something to bring CH up to around 300? (if I completely fill my pool with our appx 225 CH city water)
And what about the borates you mentioned earlier --- what chemical is that & how much to use (this is not anything I'm currently familiar with).

4. Any other less obvious things that I'm forgetting that could throw a monkey wrench into this process?

5. ASAP, get my home water softener installed & plumb a small line over to my auto-fill source so I can start auto-filling with softened water.
One question --- If I do this, it should help to keep the pool water CH lower, but couldn't this cause my pool water SALT levels to creep up instead?

Thanks, Eric
 
To drain the pool, get a sump pump rental from Home Depot. They will normally provide hoses too. Find out where you can drain the pool water too. Some municipalities say the storm drain, others say the sewer cleanout at your home.

Your size pool should drain in 5 hours or so.

Then refill. Once full, add 30 ppm worth of CYA and 3 ppm FC worth of chlorine. Adjust the pH. Then start to add your salt.
You will not need baking soda. Borates can wait for another day.
After things are settled, raise your CYA to 70 ppm and start your SWCG.

The water softener will not add salt to your pool. You will want to get your CH to about 300-350 ppm and then keep it there. You will still be adding acid to manage pH and TA, albeit at a less aggressive stance than when your CH is 900 ppm.

Only real concern on the plaster is letting it sit dry with summer sun beating down on it. So the sooner you can do this, the better.
 
[EDIT} we posted at the same time.. what he said 👆

1) rent a pump from Home Depot or buy a cheap one from Harbor Frieght type store.. also double check your ground water thing.. I would hate for you to pop your shell. In Arizona I would expect you to be fine

2) you more than one hose.. it goes faster

3) You will need CYA, Salt and CL. Get the FC level up with liquid chlorine and then let the SWG take over... everything else we will deal with when you test your refilled pool.

4) 🤔

5. Yup :salut:
 
How do I roughly determine the quantities of salt, CYA, chlorine, and other chems that I would need to treat the new pool water once the pool has been refilled? I guess the maximum quantity case would be if I fully emptied the pool. If I have most of the chems I need on hand before I start, I won't have to make a bazillion runs to the store for more chems.

If I completely empty the pool & refill with city water, the city water CH is about 225 ppm. What chem would I use to bring the CH up a little bit (300-350), if necessary?

Also, is there good technique for actually adding larger quantities of chems to the pool? I remember watching the pool company just slowly pouring bags of salt into the skimmer inlets when they started up the pool originally. Is this a good way to add larger quantities of chems?

As far as a sump pump (rental or purchase) what kind of flow rate should the pump be able to put out? Just want to make sure I'm getting something appropriate that can do the job in a timely fashion. Since you are recommending an independent sump pump, I assume this means you are NOT recommending using my pool circ pump to push water out for some reason?
 
You can use Poolmath Effects of Adding Chemicals for volumes.
You will not need to add any calcium. Just use Non softened water for fill up due to evaporation for a couple months and your CH will rise.
www.troublefreepool.com

Recommended Pool Chemicals

Which should I buy? TFP's recommended pool chemicals are cheap, easy, and won't unbalance your pool water.
www.troublefreepool.com www.troublefreepool.com
In the above article, for each chemical add to deal with chlorine, CYA, pH, etc, it explains how to add that chemical to your pool water.
Salt you add about 2/3 rds of what you are targeting. Then test the salinity after the first salt add is fully mixed (takes a day or two) then add what is needed based on your testing. Do not pour any chemical directly into the skimmer. It can damage your pool equipment.
The sump pumps from HD typically will move 3000+ gallons per hour if you use the large hoses they provide.

You really do NOT want to use your pool pump. If you lose prime as the water level falls (pulling from the main drain), you can destroy your pump.
 
Last edited:
So test your fill water to get an idea of where you are starting from chem wise. I expect your initial values of FC and CYA to be zero.. I wouldn't make that assumption with the salt.. "Don't guess test" as they say... Who is "they" anyway that says these things.. I will own it, there I just said it. ;)
 
It took me awhile to round-up everything required to do a drain & refill of our pool (to get rid of the high CH / lime scale issue) but I think I finally have everything I need.
However, at this point I have a few questions:

1. The delay in getting organized since late April/early May has allowed the daytime high temperatures here in AZ to increase into the 105-110F range for awhile now, and they are forecast to continue to stay like this awhile. I have read that high temps and direct sunlight can do damage to a pebble surface. I'd like to be able to get rid of my "snow globe" issue during the summer swim season, rather than having to wait for cooler temps in the fall. Could I pull an "all-nighter", and try to drain & mostly refill the pool once the sun has gone down in the evening? Or would I be risking damaging the pool surface if the pool wasn't completely refilled by sunrise? The temperature typically drops into the high 90s once the sun drops behind the big hill in the backyard, and is down around 80F when the sun comes up in the morning.

2. I have seen several different recommendations concerning which order to add chemicals once the pool has been refilled with water --- is there a consistent standard for this? Do I add chlorine & CYA first to establish disinfectant, -or- adjust pH & TA first to insure water is not corrosive, -or- ???? The only advice I've seen that's been fairly consistent is to add the salt last (and don't activate the SWCG until the salt is well mixed into the water, maybe as much as 24 hours after adding the salt).

3. I was planning to have to add acid (for pH), sodium bicarb (for TA), bleach (for initial chlorine), liquid CYA (for chlorine stabilization), and salt (for chlorine generation). Don't think I'll need any calcium chloride since I have so much calcium in my fill water! Any chemicals I'm forgetting?

4. There wouldn't be any need to shock/SLAM the pool after the refill, would there? My only real issue with the pool has been CH slowly increasing to sky-high levels, resulting limescale & "snowflakes" (which I'm hoping to prevent, or at least slow down, in the future by piping soft water to my auto-leveler).

Thanks again for all the help so far, this has been a serious learning experience!

Eric
 
1. The drain will take about 5 hours with a 2hp sump pump from Home Depot. The fill will take at least 16 hours and probably longer. So the plaster will be at risk. There are claims Pebble is not as effected. Believe that at your own risk.
Other idea is to exchange. See Draining - Further Reading
With high CH, salt, and your fill water most likely warmer than your pool water, a low power sump pump in the deep end and hose filling at the surface should work well. Do 100% of your pool volume.
2. Chlorine, CYA, and then salt.
3. You will never need baking soda. Chlorine, acid, Cyanuric Acid, and salt.
4. If you have active algae now, yes, SLAM the pool after it is refilled, Add 30 ppm CYA and follow the process.
 
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