Concrete pool with "knots" along the bottom edge

I was wondering if anyone had any idea what these knots are. I'm not sure how else to describe them. I bought a house in January and it came with a swampy concrete pool. With the help of TFP, I now have a sparkling clear pool. Now that I can see the bottom clearly, I noticed these knots along the edge of the pool. Most of them are in the shallow end (3'6" deep) and by the skimmer (4'6" deep).

A little history about the pool as I have been told by the previous owner:

It was built roughly 1950's
The previous owner drained the pool every single year because he said it was easier to start with fresh water :shock:
It has about 3 different paint layers of different colors...meaning he painted over the old paint each time
The shadow at the bottom of the pool in the post TFP method pic is actually a painted killer whale

This is an image from the appraisal showing the swamp
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This is the pool now post TFP method
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These are the "knots"
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20160619_094703.jpg
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If anyone has any idea what they are and if I should be concerned about them. I definitely don't want them to get any bigger. I do plan on doing a pool renovation next year but for this season I just wanted to be able to swim in it.

Thank you!
 
I want to see a better picture of the killer whale! That looks neat!

How do those knots feel? Any give to them? Are they chipping off? Are you losing any water that you can tell?

I would not do too much to them just in case. We ALL want you to swim and enjoy your pool!

Kim:cat:
 
I have yet to get in and actually touch them but when brushing they seem solid. It's hard to tell if there are cracks in them or the cracks are the paint cracking. I have noticed a small amount of water loss but but I have cleaned my filter a few times and yesterday there were quite a few people splashing around. I will check them better tomorrow and will post a better picture of the whale.

Thanks!
Bridget
 
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