Calcium Crystals

nopain00

Member
May 27, 2017
17
Warren, NJ
Moved from here.
I'm jumping on this thread because I have the same issue. I've winterized my pool many times before and this is the first time I found calcium crystals. The only difference this year was that last year we got a new Hydrazzo plaster. At the time of closing, my parameters were:

Cl 10 ppm
pH 7.7
TA 80 ppm
Ca 360 ppm
CYA 60
Salt 3400

When I opened the pool and filled with new water, the parameters were

Cl 0
pH 8.5
TA 70 ppm
Ca 300
Salt 2500
CYA 20

I did not check the water prior to filling. I found sharp crystals only below the winter water line, only on the plaster and grout, and not on any other surface like the tile faces. My vacuum was picking them up by the bagful. In my search, I found the Orenda blog that others have talked about. I understand their point. My LSI and CSI were balanced at the time of closing, but since temperature is a factor, water that's balanced at a summer temperature (>80°F) becomes corrosive at a winter temperature (<40° F).

I wanted some advice on anyone that has used SC-1000 or another method. I've balanced and heated my water and brushed the walls. Some of it has come off, but some of the crystals remain. From what I understand, SC-1000 is a chelating agent. It chelates many ions including calcium, reducing the effective concentration of calcium, which drives the solution reaction to help dissolve the crystals. I also understand that it binds chlorine.

Has anyone else used this stuff? Does the split-dosing system work, where you add a fraction at a time, allowing the chlorine to build up between additions?

What does the calcium level measure as you are using this? Does it go up since more is being solubilized, or does the test read a low level since the Ca++ is chelated?

I'm really hopeful that this can be fixed without an acid wash.
 
Last edited:

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
33,058
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
"00", while I personally have not used SC-1000, I have used other such products and found them to not be worth the $$ or effort. In addition, they tend to mess with other chemical levels and create more problems. What you are experiencing at opening isn't totally unusual since your pH shot-up during the winter. I would use the PoolMath APP to load all of your test results, then adjust the pH back down to the mid-7 range and increase your CYA a bit - either a 30 min CYA if the SWG is still off, or to about 70 in in preparation for SWG use. Using the PoolMath APP, take note of your CSI and keep it in the -0.1 to -0.3 range for a week or two. With that lower (slightly negative) CSI and consistent brushing you should see those crystals begin to disappear. If not, let us know.

Since your first question was focused on the SC-100 product, post back as much as you need to for replies.
 

nopain00

Member
May 27, 2017
17
Warren, NJ
Thanks, Texas Splash for your quick reply. I'm trying to understand my goals for the LSI/CSI better.

I understand that a high saturation index leads to scaling. I always thought a low LSI/CSI would lead to etching of a plaster pool, but this article says that another consequence are these crystals as the water is drawing calcium out of the plaster.

Now that my pool is open, it's once again balanced.
FC 5.0
pH 7.7
TA 80
CH 360
CYA 30 (and rising as I slowly add more)
Salt 3400
The CSI calculates to -0.02.

At this point, if I keep the LSI/CSI negative, would it help dissolve the crystals like you say or cause more crystals (as it did over the winter)? By the same token, will a high CSI help stop creating these crystals or make it even harder for them to solubilize?

In any case, I'm brushing often with hopes that it will correct it. I'll wait to hear what others say about their experience with SC-1000.
 

onBalance

TFP Expert
LifeTime Supporter
In The Industry
Jul 25, 2011
1,186
Utah
Nopain00, you are correct that a high LSI/CSI index means scale may develop, and that a negative index means that etching may occur. Crystals are not caused by aggressive water and a negative CSI/LSI as is suggested by some. My research on this topic indicates that sometimes new plaster contains excess calcium chloride, which exits the plaster surface along with some soluble calcium hydroxide and leads to crystals developing on the surface. (That is why the pH rose so high). This crystal formation occurs when the pool water is within a balanced range, not in an aggressive condition. As you stated, etching is caused by aggressive water by dissolving and removing calcium from the plaster. That negative index condition does not cause calcium crystals to form.

Adding SC1000 may help to dissolve crystals, and also from forming in the future. There is a less likelihood that crystals will form next winter as the plaster had furthered cured. But it may happen again the second winter depending on the amount of excess calcium chloride added to the plaster mix.

It is always best to the balance the pool water by planning and adjusting for colder water temperatures to prevent etching.
 

shoot_the_goalie

Well-known member
May 15, 2018
57
NY
I had this same problem one year after opening my Hydrazzo pool. Small crystals all over the pool walls, only under the waterline, easy to remove but a pain to clean cause of the amount. The crystals would also bubble when pouring vinegar on them. I'm still not 100% sure what caused the issue, but I read the Orenda article as well as other sites, and decided that in the future I would keep my CH pretty high at closing, so if my water was starved for calcium, it wouldn't leech it out of the plaster. (the opening it happened, by CH read 200 at opening) I still am not sure why it happened or why it's hasn't happened again, but every closing I make sure to keep my CH at or above 450 (and at opening it's usually around 350), and the problem has never reoccurred. So take that for what it's worth.
 
  • Like
Reactions: nopain00

nopain00

Member
May 27, 2017
17
Warren, NJ
OnBalance, thanks for your response. I was skeptical of aggressive water causing crystals. I would expect crystals to form when there is an excess of a chemical and it deposits on a crystal nidus. Your comments about CaCl and Ca(OH)2 make sense as the pH went up.

@shoot_the-goalie, what did you do to remove the crystals? Metal brush?
 

shoot_the_goalie

Well-known member
May 15, 2018
57
NY
OnBalance, thanks for your response. I was skeptical of aggressive water causing crystals. I would expect crystals to form when there is an excess of a chemical and it deposits on a crystal nidus. Your comments about CaCl and Ca(OH)2 make sense as the pH went up.

@shoot_the-goalie, what did you do to remove the crystals? Metal brush?
It was a PITA but I brushed as much as a I could (it came off with a regular brush) and then ran my Polaris over and over and over (and over) again til all the crystals were vacuumed up. Please note that 1) the Polaris bag will fill up fast and 2) the crystals are heavy so you’ll know you have to empty the Polaris when the Polaris rides on its side cause the weight of the crystals is causing it to lean over. I also had to go through 2 Polaris bags cause all the weight did a number on the mesh bags and roughed them up good. Good luck!
 

nopain00

Member
May 27, 2017
17
Warren, NJ
Thanks. You're describing my situation exactly. I emptied several full bags and had the issue with the scrubber wearing down, as well as the bag, as you said. The bagfuls of crystals has stopped, but I am seeing some white powder at the bottom of the pool, which I assume are smaller crystals that go through the bag. I'm brushing daily and running the Polaris over it with hopes that it will get better. I don't have an objective way of checking to see how much of the crystals are left. The walls still seem rough, but I can no longer see the white crystals on the walls.

How long did it take you to get your smooth walls back?
 

shoot_the_goalie

Well-known member
May 15, 2018
57
NY
Hey nopain00. Once I got all the calcium crystals out, my walls felt like they originally did, but it took a while (probably over the course of 3-4 weeks). The good news is I highly doubt you'll need an acid wash. I dealt with the fine crystals (almost looks like dust when it kicks up), by changing the Polaris bag to the fine mesh bag that they manufacture. Then finally, I brushed and brushed and got the filtration system to do the rest. (I kept sweeping toward the main drains) Then after that, I had to clean the filter and filter cartridges as a good quantity of crystals were stuck in there. Like I said, it was a PITA. I have a Dolphin robot now...and I would imagine with the fine mesh screens installed, it would at least save some of the labor.
 
Thread Status
Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.