Strange growths on surface as of late

May 17, 2016
Fort Worth
I've been having some strange growths along the sides and floor of my pool, which I'm assuming to be gunite.

More recently: An algae-like substance, that takes a lot more work to scrub off than the usual buildup during SLAMing, which I just completed a few days ago. It's also more brown. I rubbed it with a lime, which had some effect but didn't take it all off. I wouldn't say the results were much more of an improvement over some hard brushing. If I could correlate some event to it, maybe it's after I added a phosphate inhibitor (phos-free type of Leslie's chemical) but that's all I can think of. The phos-free was pretty old, and had sat outside, though not in direct sunlight.

Overall for the past year or year and a half: Small dots (but all over the pool) of these very, very hard deposits of what look to be calcium (silicate?). They are very hard to remove. Is this going to require a scaling chemical solution or am I going to need to chisel them off? It wasn't always like this in my pool. Not sure what is changing in the chemistry. We did have a massive drought a couple years ago and then a massive few months of rain, enough to fill up all the lakes again. Possible issue there?

I will note that I did drain the pool a year ago and left it empty for a bit longer than I'd liked to. It did put some emphasized cracking on some cracks that had already developed. Those cracked locations began to develop a white substance that is similar in color to these hard deposits. Is this indicative of a pretty serious underlying issue? My pool is not losing water.

I am in D/FW, TX. I am fairly new to these pool forums, so forgive me omitting any pertinent information or any ignorance.

Pool Test:
TDS: 500
Copper/Iron: untested
pH: 7.8
Alk: 80
Free/Total Chlorine: 0/0 (just cleared up the pool and added phos-free, which requires low chlorine to my understanding)
CH: 220
CYA: 0
Phosphate: 0


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I will post an image of the cracks once I figure out how to make it allow further attachments.


Last edited:


Bronze Supporter
Dec 22, 2016
Arlington, Texas
Howdy Richard. Looks like we need to get you away from Leslie's. They just want your money. You need to get your own quality test kit. You need either the Taylor k2006 or the tf100. With you having an inline chlorinator, I bet your CYA is not 0 unless you haven't been using tabs.
May 17, 2016
Fort Worth
The chlorinator has not been refilled yet. Though i do smell that lovely heavy chlorine smell when I turn the system on, so maybe there's a little.

I will check out those kits, thanks.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
Any understanding of what might be happening here?
Yes, your pool is chronically under chlorinated. Getting it cleaned up and crystal clear is reasonably simple but will take some physical effort and, primarily, a mental effort to tune in to the TFP way.

My suggestion is to Please read "The "ABC's of Pool Water Chemistry" up in Pool School. You'll have questions after that and we'll answer them but you need to under stand that that green algae is a lack of chlorine.