First Time Opening, New plaster last season: scaling and sharp crystals

jeffr47

Bronze Supporter
Oct 19, 2018
118
Rockville, MD
Hi,
We just opened yesterday and I'm sad to say that the previously china-like surface of my new plaster is covered with deposits of sharp crystals. After running overnight, the sweeper was full of crystals as well. Running my hand over it, it feels like a very coarse sand paper. Calcium carbonate, right?

The pH is very high, I don't know how high yet because it's off the top of my testing kit's scale (8.6).

Full numbers (before adding chemicals)
FC 1.5
TA 80
CYA 25
pH > 8.6
CH 300
CSI 0.68

I've added 80oz 31.45% muriatic acid and will continue to add/wait/retest until the number gets down to 7.2 or so. Brushing with a nylon brush did not seem to dislodge any deposits, at least not yet. Should I get a metal brush? I don't want to do anything rash and cause damage.

Is it possible to get back to a nice smooth surface after this sort of thing?
 

kimkats

Mod Squad
LifeTime Supporter
Jul 10, 2012
44,828
Tallahassee, FL
NO!!!!!! I know your heart skipped a beat when you saw in :( Can you please take a few pics of the pool and what your cleaner is getting up. This will give us something to work with.
 

JamesW

TFP Expert
Mar 2, 2011
18,482
You're probably going to have to begin dropping the TA until the scale begins to dissolve. You might have to go to zero TA.

If you have to go that low, I would take the system offline and remove any metal from the pool.

Brush everything well. Get a wide nylon brush.

This is a risky procedure that might not work and might even cause unintended problems.

I can't recommend it due to the risk.

If you choose to do it, you do it at your own risk.
 

jeffr47

Bronze Supporter
Oct 19, 2018
118
Rockville, MD
NO!!!!!! I know your heart skipped a beat when you saw in :( Can you please take a few pics of the pool and what your cleaner is getting up. This will give us something to work with.
Was "No!!!!" a cry of dismay at the scaling, or a response to a metal brush?

I'll get some pictures later today when the light is better. I tried yesterday but the reflections made it pretty hard to see anything helpful.
 

jeffr47

Bronze Supporter
Oct 19, 2018
118
Rockville, MD
Here's what I'm looking at. The crystals are from the sweep, after they dried. On exposure to acid, they bubble.

I've got the pH down towards neutral now and the CSI is negative again. I can brush with my nylon brush, although at least initially that seemed to have no effect.
 

Attachments

JamesW

TFP Expert
Mar 2, 2011
18,482
You're in a difficult situation. To get the scale to dissolve, you're going to need to get aggressive with the TA.

I would probably lower the TA to 0 with the equipment off and drained.

Then brush until all of the scale dissolves.

The pH will be about 4.5, which is aggressive to metals and the plaster.

You should remove any metal from the pool.

After the scale is dissolved, bring the TA and pH back up and restart the system.

This is a risky procedure and you have to decide if you think that it's the best choice.

It might not turn out like you want. There might be unanticipated damages.

Due to the risks involved, I am not recommending the procedure.

If you decide to do it, it's at your own risk.

Maybe consult with a local professional expert to see what they recommend.

You can try lowering the pH to 7.0 for a while and brushing frequently to see if that eventually works. That might be the safest option.

Sulfamic acid (Jack's #2 copper and scale stuff) might work but it will lock up the chlorine for a month or two.
 
Last edited:

jeffr47

Bronze Supporter
Oct 19, 2018
118
Rockville, MD
You're in a difficult situation. To get the scale to dissolve, you're going to need to get aggressive with the TA.

I would probably lower the TA to 0 with the equipment off and drained.

Then brush until all of the scale dissolves.

The pH will be about 4.5, which is aggressive to metals and the plaster.

You should remove any metal from the pool.

After the scale is dissolved, bring the TA and pH back up and restart the system.

This is a risky procedure and you have to decide if you think that it's the best choice.

It might not turn out like you want. There might be unanticipated damages.

Due to the risks involved, I am not recommending the procedure.

If you decide to do it, it's at your own risk.

Maybe consult with a local professional expert to see what they recommend.

You can try lowering the pH to 7.0 for a while and brushing frequently to see if that eventually works. That might be the safest option.

Sulfamic acid (Jack's #2 copper and scale stuff) might work but it will lock up the chlorine for a month or two.
I think I'll stick with lower pH and lower TA, but not as aggressive as 0. For brushing - nylon brush or metal?
 

JamesW

TFP Expert
Mar 2, 2011
18,482
I would try the nylon first and switch to stainless steel if necessary. Don't use stainless steel bristles on tile.
 

jeffr47

Bronze Supporter
Oct 19, 2018
118
Rockville, MD
How low can I "safely" go for pH if I want to try a gentle approach? I'm at 7.2 now. I was thinking of going down to 6.8 or so. I don't have a heater but don't want to damage my pump, light, or DE.

We aren't going to be swimming for some time anyway, so I'm willing to give the process some time...
 

JamesW

TFP Expert
Mar 2, 2011
18,482
Metal is most susceptible. I don't know a "safe" low pH.

pH is a logarithmic scale. So, a pH of 5 is 100 times more acidic than a pH of 7.

The lower you go, the better the scale will dissolve but the risk is also greater.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
16,163
Northern NJ
I would lower your CSI to around -0.6 to -0.7 by lowering the pH which gets the water aggressive and give it a few months.

As James said the lower you go the better and quicker the scale will dissolve. But a something less agressive can dissolve the scale, it will just take longer.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
16,163
Northern NJ
 

JamesW

TFP Expert
Mar 2, 2011
18,482
Jack's #2 copper and scale stuff is sulfamic acid. It might work, but you can't let it make contact with anything copper like in a heater.

It will also convert the fc to cc for a few months, which is annoying, but manageable.
 

jeffr47

Bronze Supporter
Oct 19, 2018
118
Rockville, MD
I don't have a heater, so I think this might be worth a shot.

The big issue is the FC level... I'm a bit concerned about the availability of bleach right now. Couldn't get any of the HDX germicidal from Home Depot I usually use.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
26,826
Laughlin, NV
Look for liquid chlorine. Home Depot typically has it in the Garden Section. Walmart too. Menards is reported to have it. Household bleach is hard to find, but liquid chlorine is reported to be available.
 

jeffr47

Bronze Supporter
Oct 19, 2018
118
Rockville, MD
Thanks. My Home Depot doesn't carry liquid bleach and we don't have Menards. Nearest Walmart does seem to have it, so I'll keep that on standby. It's not all that nearby and I've actually never been!
 

Drewb4

New member
Jul 26, 2019
2
Bolton, MA
Jeff do you have an update to this?

We opened our Northeast pool Friday to the same problem. It was a new plaster finish from last summer. My first opportunity to check chemicals was early march-- was frozen most of the winter. I added some acid... however still encountered this problem.

There was another thread where someone took a pole sander with 200 grit. Wondering if that would work....
 

jeffr47

Bronze Supporter
Oct 19, 2018
118
Rockville, MD
I've added 192oz (for a 24000g pool) of Scaletec and have been keeping the pH near 7, so my CSI is strongly negative. I've been brushing regularly with a metal brush as well. I think it's getting slightly better, but it's hard to judge and I can't feel the bottom of the pool at all. The water temp is still in the low 50s.

Once I can get in the water I might consider a pumice stone. The polesander is another idea - with wet sand paper I suppose?