Acid Wash white plaster pool

[DebiA]

I purchase a home in southern Texas in March. We have a in-ground (36x16) 18,000- to 20,000 gal. pool,White Plaster. I had a small crack in the bottom so we decided to have the whole pool re-plaster by a professional company.By April it was finished. The Pool guy we hired came out the day it was finished and said to fill it, and he would acid treat it once it was filled. when filled he poured in the acid and brushed the pool with wire pool brush, and had us brush it everyday for about 6 weeks. It is now August, we have a build up on the walls that looks like sand (rough). it started to turn green so our guy shocked it, but the green is only were that build up still remains. It comes off if i scrape it with a putty knife. but i do not want to damage the plaster. can you tell me what is going on?
DebiA

 

[jblizzle]

Welcome to TFP!!!

Please post a full set of test results (pool-school/read_before_you_post)

What was the intial start-up pool balacing done for the new plaster?

It kind of looks like you let the pH get way too high and then calcium scaling occured on the walls (the roughness) and then you let the chlorine get too low and algae started (the green).

 

[ping]

To start can you give us a full test of the chemical levels which will includes the following and how you got them:
FC
CC
pH
TA
CH
CYA

Please put all of your pool equipment in your signature. Did you use well water or is it municipal? Are there any known metals in the water?

It looks like the calcium levels got too high for your pH level and you now have calcium scaling with algae inbedded in the rough spots.

 

[DebiA]

IG,Sand, Hayward pro series S244T, Whiteflo 1.5 HP Pump,White Plaster, 20,000 gal., polaris, attached Spa
FC-1
CH-240
CYA-20
TA-120
pH-8.0
and i am not sure what CC is because it is not on my test results from pool place.Knowing nothing about pools when we purchased the house, we hired someone to do the water testing, and we work all day. so we are trying to learn but prier to the last 3 weeks we do not know what the water chemicals have been. the home was built in 1980, therefore i do not know how old the pool is. all of the equipmemt is dated 2008.

 

[jblizzle]

If you are intending to take control (or even if you just want to be more knowledgeable), you should read through Pool School {button at the upper right of the page} a few times. Also, you should realize that we do not put much faith in pool store testing which has repeatedly proven itself to be worth what you pay for it. As such, one of the Recommended Test Kits is suggested to truly understand your water.

While your CH is not very high, the pH is and if it was allowed to get much higher could very well results in the calcium scaling you appear to have. Additionally, the FC is too low based on your CYA level which is also a little low. You should not let the FC get below 2ppm or algae can start: pool-school/chlorine_cya_chart_shock

You can read about calcium scaling in Pool School as well: pool-school/calcium_scaling