Calcium Deposits on pool wall

[onBalance]

Yes, temperature change will expand and contract the pool plaster and consequently cause the plaster to lose its bond to the old plaster. Draining the pool also dries out the plaster and causes it to shrink.
Generally, on new or orginal plaster jobs, the bond is so good and tight to the gunite (both a mechanical and chemical bond) that draining the pool won't cause any delaminations. But on re-plasters, it is very difficult for the plasterers to get as good of a mechanical bond (and no chemical bond), so delamination is what can happen. Sometimes, the loss of bonding happens immediately and nodules show within a couple of months, and sometimes it takes several years for delamination to occur, especially after draining the pool. It all depends on how well the plasterers bonded the new plaster to the old plaster. And pH balancing has nothing to do with it.

 

[Moses Whippy]

Hi.

The white deposit is due to a crack(s) in the shell of the pool wall when the shell was built.
Water from outside the swimming worked its way through the crack(s) and as it passed through the crack(s) it carried with it the uncured chemicals of the concrete with it and deposited the lime etc., outside of the crack.

When the pool was plastered directly of the unsealed crack the same thing happened there with the water now passing through the finish also.

If the shell had been waterproofed/sealed after being shotcreted or gunited the leeching probably would have not occurred.

The solution here is remove the plaster finish where the leeching has occurred and seal off the crack in the pool shell first and then redo the plaster.However this will look awful so the best thing to do is to install a mosaic tile design there instead.

I hope that this will help.

 

[onBalance]

IMO, a crack in the gunite shell of a pool and leading to a crack in the plaster finish is plausible, but not probable. It would have to be a very large and long crack that was able to have movement to result in cracks in the plaster layer.
Yes, the gunite shell can have some very small surface cracks caused by shrinkage, but the purpose of pool plaster is to seal and water-proof the pool gunite shell.

If this pool has been replastered (five years ago) with new plaster covering the old plaster, then the gunite shell would probably not be an issue. When delamination of new plaster occurs, it will also cracks at those sites. One can tell if the plaster is delaminating by simply tapping next to the nodules with the handle of a screwdriver and listen for a "hollow" sound and compare to areas away from the nodules.

 

[carolina pool]

+1 on what onbalance said about shell cracks.

These voids are usually a result of the plasterer trying to lay up too much material and it slumping away from the surface. They show up as bubbles during the process and instead of scratching them out, they just pop them and smooth them out. You can chip them down and smooth them out with a worn carborundum stone.

 

[trident]

I just found this thread. I have the same type of deposits and spots on my pool! I bought a stainless steel wire brush but the spots won't budge.

Here is what else I know:

My pool is about 40 years old, maybe more. I just bought the house less than a year ago so I have no idea how long these spots have been on the pool. The pool was probably replastered a few years ago but I have no idea when. I did notice a crack in the wall a couple of months back but I have no idea what to do about it.

So should I worry about the crack on the side of the pool? How do I get rid of the spots like the guy had in his pics? My spots look exactly like that.

Sometimes I wish I hadn't gotten into this but here I am.

 

[onBalance]

Cracks in the plaster surface generally means "delamination" of the top layer away from the substrate. It generally does NOT mean that the entire pool shell is cracked, which would be a serious issue. You can scrape the calcium nodules off, and then use epoxy to seal the cracks.

Other than that, at some time your pool may need another re-plaster job.

 

[trident]

Thanks! That's better news than I thought.

Still, how do I get rid of the calcium? Can I do it chemically?

 

[onBalance]

If you are talking about removing calcium (if it is high) from the pool water, then draining some water out and refilling with softer water will do that. Can't do it chemically.
But pool water always needs a certain amount of calcium in the water to keep it from being too aggressive.

However, if you are talking removing the calcium nodules chemically, then that is problematic. It really is not feasible. Making the water aggressive to remove nodules will also make it aggressive to everywhere else, and that will just etch the rest of the plaster surface. That is why I suggest scraping each nodule to remove them. If there are a lot of them, then maybe it is just not feasible to do that.

 

[ElementZero]

FYI someone asked me if I had solved this question so I wrote him back this...

My pool was kind of bad off and I was thinking about getting it refinished so I'm getting that done soon so I didn't bother too much with this after decided to go that route.

That being said, I tried brushing it off with some steel wool and a steel file and that only managed to leave a mark on the cement and didn't really take the stuff off. I did use a screwdriver and chip a piece off and then put some muriatic acid on it - the stuff completely dissolved. So I lowered the water level some and the spots that were near the top of the water line I just threw acid on them and they completely vanished.

The problem is the spots on the bottom of the pool. For that I thought about it and I was going to try something like this

http://www.amazon.com/Purity-Pool-OS-St ... m_sbs_lg_1
or http://www.poolsupply4less.com/Jandy-St ... 4AodeEgArQ

or just a long piece of pvc (cheaper but way more difficult as you have to cover the top so it holds the air in and then lower it straight down without the water getting in) and then you could basically basically put that over the spot and pour the acid on it right on the spot. I know the pvc would probably work, the stain remover looks like it would work as well, just never tried it (would just need to make sure it had a hole on the bottom for the spot to fit in - it it's completely flat on the bottom it wouldn't work obviously so you'll have to go the pvc route).

There was another suggestion someone had to get some fine sandpaper and just sand the spots down but given how many spots I had and the fact that some of them are eight feet down under water AND the fact that I had scrubbed them hard with a file and a steel wool to near no effect that seems a little more difficult or even impossible.

Anyways, being able to apply acid directly to the spots seems like the way to go on this. Hope that helps some!

 

[onBalance]

Yes, using acid directly on the spots will dissolve the calcium nodules. However, understand that the small areas immediately around the calcium nodules will also be etched in the process.
The nodules will dissolve quicker and easier than the rest of the plaster surface, so it is possible you will be satisfied with the results.

 

[samanthar]

I am so so happy to see this posting!! yes I know its a super old post but I have been looking and looking for a solution to these mystery white crusty things in my pool. I am vigilant with my water chemistry so this was making me nuts. Had our pool replastered 5 years ago and these things started showing up about 6 months ago. I can tell you they do eventually flake off and take a chunk of your plaster along with it. I will be much more careful about choosing the next plaster company...a job I hadnt anticipated for another 10 years

 

[onBalance]

See this below link for a better understanding of how and why calcium nodules are formed.

Calcium Nodules in pools

 

[Limey]

I think I've joined the calcium nodule gang. Noticed a few of these after the pool light was switched on at night at the bottom of the gunite pool. The pool was replastered in 2011, and the pool was emptied in March 2018 for remodel work of the deck . I guess that played a factor.

 

[CFlaPool]

I think I've joined the calcium nodule gang. Noticed a few of these after the pool light was switched on at night at the bottom of the gunite pool. The pool was replastered in 2011, and the pool was emptied in March 2018 for remodel work of the deck . I guess that played a factor.

I know, this is old thread, but it’s exactly what I need. After a re-plaster three years ago, I am finding these same nodules on walls, benches, etc. Searching the forum is always the best first step. You all, especially OnBalance are great!

 

[proavia]

I know, this is old thread, but it’s exactly what I need. After a re-plaster three years ago, I am finding these same nodules on walls, benches, etc. Searching the forum is always the best first step. You all, especially OnBalance are great!

It would be best to start a new thread and link to the old one if you need to reference it.
This thread hasn't seen a reply for over 5 years.

 

[CFlaPool]

It would be best to start a new thread and link to the old one if you need to reference it.
This thread hasn't seen a reply for over 5 years.

I did not see an easy way to refer to this thread, and i just wanted to say that old threads are worth keeping around.

 

[proavia]

I did not see an easy way to refer to this thread, and i just wanted to say that old threads are worth keeping around.

When viewing an old thread - click the address bar, select copy and then paste the link in a new thread of your own.

Old threads aren't going anywhere. But there is a Thread Status warning notice at the bottom of threads that haven't seen a response in over 60 days. That's a hint to start a new thread.

Thread Status
Hello <your_user_name>, This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.

Most of the time, necroposted topics are resolved and/or irrelevant in today's terms. When someone necroposts, it clogs up the first page with resolved and outdated topics that are no longer relevant, taking attention away from newer, more relevant topics.