Plaster issue - pool plaster turning white

[saltybp]

I know I will be asked so I will start with the stats ( I have a Taylor K-2006 test kit) but the numbers below are from Leslie's Pools today:

FC- currently low
CC - currently low
CH - 360
TA - 110
CYA - 50
PH - 7.3
No heavy metals

The issue appears to have developed over the winter, it was like this when I opened the pool this year. The pool configuration is a hot tub with a spill over into the 18,000 gallon SWG pool. When I lower the water and blowout / cap the pipes for winterizing the hot tub and pool at that point are separate bodies of water. I make this point because the pool has the issue, the hot tub does not. The folks at Leslie's were no help, a knowledgeable friend told me to use a wire brush. I would prefer to know what the issue is before trying different things.

I will add that before I knew better I used clorox 6 in 1 shock powder every 1-2 weeks during the swim season. I also used it when closing last year. I keep PH and TA in check with baking soda and muriatic acid. I have switched over the HDX liquid chlorine from Home Depot for the swim season weekly FC pickup.

The plaster should be the dark blue with specks seen in the floor of the hot tub (the walls look black in the photo but are not). The other picture is a step in the main pool, but just about all of the main pool looks whitish. The plaster is quartz plaster.

Any feedback would be appreciated.

Thanks
Bill

 

[ajw22]

Likely blue organic color was used. Read Not All Color Pigments are Good for Pools

 

[saltybp]

Thanks for the reply, my question would be why does the hot tube look fine? It is all connected, all the same finish. Is it possible it is temperature related?

 

[saltybp]

I took an 8oz water bottle and filled it with 50/50 water acid. I applied the acid solution to a small area under water and took the white right off. so I am thinking this is some type of calcium or scale? There is no way I can do the hole pool with little water bottles. Should I really be needing to drain and acid wash a 3 year old pool? Are there any other options?

 

[ajw22]

You can try keeping your water at an aggressive CSi around -0.6 for a season or two and see if it slowly erodes the scale. That us a very slow process.

 

[mknauss]

I assume you have a heater. If you do any acidic treatments, even low CSI treatments, you need to bypass your heater.

There are aggressive methods, but they take care and diligence.

Can you post a set of test results from your own test kit?

 

[saltybp]

I just drained and replaced about 25% of the pool water. I was using the 6-1 pool shock and despite what the Lesly pool test result was, my CYA tests were over 100. I finished filling to pool early this morning and just ran my test:
FC .2 (I added 128oz of hdx liquid chlorine after this test was done)
PH 7.2
TA 80
CH 255
CYA 60
Temp 76
CSI -.58

 

[mknauss]

What is 6-1 pool shock?

 

[saltybp]

Clorox Pool&Spa XtraBlue Shock

 

[mknauss]

Clorox Pool&Spa XtraBlue Shock

OK - Dichlor with copper.

Evil stuff. One of the reasons you CYA is very high. The copper will eventually stain pool surfaces and does turn blonde hair green.