Possible Calcium Scaling

[TKH]

I'll start by saying that this site has been very informative and I feel like I'm learning a lot. But it seems the more I learn, the more I realize that there is so much I don't know.
So here's my novel. Please bear with me.
My story is pretty much the same as so many others on here. Bought a house with a pool. Hired a service because we knew nothing about pools and went along happily for a year or so.
Well, sort of happy. According to the service, we battled mustard algae regularly and once a week service couldn't cut it. So I found myself going to the pool store and spending a ton of money on top of paying someone to take care of my pool.
My husband finally said enough is enough. We let go of the pool service and I took over upkeep. Found this site and started the TFP method. The pool has never looked better. I, of course, discovered that my CYA was way too high thanks to pucks. From what I could tell with a 4 to 1 dilution it was around 280. Calcium was 675 - probably due to the constant shocking for the algae.
Through reading, I discovered that what our pool guy kept calling a mustard algae was actually metal staining. No wonder it never went away when he was shocking the heck out of it!
I did the ascorbic acid treatment with wonderful results, but thought I saw evidence of calcium scaling. We did a series of partial drain/refills with a lot of help from the all the rain and have gotten those numbers down.

The latest set of numbers are:
Water Temp 86-89
FC 5
Ph 7.3 (pool likes 7.5 but trying to keep it lower to help with scaling?)
TA 90
CH 275
CYA 40
Borates 15 (will bring that up to 50 when I get the other stuff sorted)
Salt 1180 (added based on several people recommending it on this site)
According to pool math, this has my CSI at -.12. I believe that is good.

I have been using ProTeam Metal Magic to sequester the metals. Two days ago I decided to add Scaletec Plus to see if it would help with the scaling. Last dose of Metal Magic was a week before. I added 128 oz of the Scaletec which was about 60 oz short of what was recommended. Within a couple of hours the pool went pretty cloudy. I panicked a little but read somewhere that this could happen. So I let the filter work and it is almost perfectly clear. Pre TFP I would have said it is clear. Then today, I found a chunk of white, gritty "rock" that crumbles easily in the basket part of my filter pump. I have attempted to attach a picture of it. Can someone help me determine whether it is calcium? Did this come off my pipes and if so can I assume more is in there?

And most importantly, did I totally screw something up by adding too much "stuff" to my pool?

Thanks for any advice/ help with this.

 

[Richard320]

Welcome

How big is that rock?

It could be Calcium scale, it could be a piece of errant concrete from around the skimmer well, or it could be some hardened up pool stuff if the old pool service was fond of pouring chemicals into the skimmer. The test for Calcium is to drop some muriatic acid on it and see if it fizzes. Sadly, scale, concrete, and Cal-hypo pool shock will all fizz, so it doesn't narrow things down much. I suppose if it didn't fizz you'd know it wasn't Calcium, so it could be some hardened up miracle pool treatment from the past.

Real scale is grow-your-own sandpaper. If you see smooth blotches, it's probably a crummy plaster job finally showing up. I have a lot of that. As time goes by, I can see trowel sweeps.

 

[TKH]

Thanks for the welcome, Richard.

It's about 1 1/2 inches across and maybe 1/4 inch thick. It definitely sizzled with the acid and is very rough and somewhat porous. It has the appearance of having been inside a pipe in that it is somewhat curved/smoother on one side. It's still porous and rough, just not so much as the side you see in the picture.

So, maybe I didn't start some terrible chain reaction where 14 years of calcium build up will break loose from all the pipes and rush towards my pumps and ultimately cause all of my equipment to fail at one time?

I kid. But not really.

Should I lay off the Scaletec?

 

[duraleigh]

Maybe I am not understanding but why are you using the scaletec? Your numbers show no indication of a scaling condition and you have no visible evidence of scaling, correct? Seems to me you could do without it.

 

[TKH]

My first set of numbers that I ever got with my TF100 test kit were:
FC 9.5
PH 7.8
TA 140
CH 675
CYA 280ish

Pool Math came in at a potential for scaling, which at the time, I didn't really think much about because as soon as I brought my numbers to line up with TFP recommendations, it read as balanced.
My current numbers are after a couple of months of doing my own maintenance and going through several drain/refill cycles to bring down CH and CYA.

When I did the AA treatment last month, lots of staining lifted off, but these grayish (at least against my white plaster) splotches/streaks stayed behind. I think they might look like scale. I'm not 100% sure. But, since the pool is 14 years old, and it could have had those original "potential scaling" numbers for a long time, I decided to do the scaletec thinking it could possibly help with the scaling and if not at least act as a sequestriant for the metals since I have to treat for that now.

 

[onBalance]

That chunk of rock does not appear to be pure calcium carbonate (as in scale), but also contains aggregate.
Therefore, I am pretty sure that is simply a small chunk of original pool plaster that broke off, probably from within the main drain, and got trapped in your basket.
Nothing to worry about, and chemical treatments did not cause it to develop.

 

[chiefwej]

I did have scaling in my pool. Years of water not being balanced and the tile surface on the benches in my attached spa felt like sandpaper, only sharper. Once I found TFP and learned to balance my pool chemistry, I began to keep a close watch on the CSI. I kept it very slightly on the negative side to avoid any further scaling. To my amazement, over the next few months all the scale in the pool began disappearing. The calcium level in the water went up as the scale dissolved back into the water. Then it got so high (over 1,000) that I ended up having to drain and refill, but the pool was free of any scale, and it was done without having to do an acid wash.

Moral of a long story, keep a close watch on the CSI and scaling will never be a problem

 

[chem geek]

Note that the same negative CSI that allowed for calcium carbonate scale to dissolve is the same that can dissolve plaster. It's just slower with plaster since the calcium carbonate is bonded and mixed with aggregate and calcium silicate hydrate. This is why having the CSI not be too negative is important, especially if plaster is not well-made.

How negative was "slightly negative"?

 

[chiefwej]

Well within the range listed as safe on Pool Math. Usually it was around -0.1 or so. Like I said just slightly negative. Nothing even near the -0.6 that Pool Math allows. I still keep my CSI neutral or very slightly negative to avoid scale, since my calcium levels are so high. High alkalinity and high calcium in my fill water makes things a little bit of a challenge.

 

[TKH]

Thanks, onBalance. That makes me feel better.