Dirty Plaster

  • Last Post 08 August 2022
Steveinmypool123 posted this 07 August 2022

In groung pool rectangular, 32 feet by 15 feet, 2-1/2 foot to 5-1/2 foot deep , 11 foot spa with water fall, salt water, chlorine gen, approx 13.5k gallons. Pool is 14 years old, I have owned it since 2016, Location Charlotte NC  

Uncovered  the pool in April, water looked good/actually great,. couple of worms and leaves got into the pool under the cover during the winter. Cleaned the pool filled to normal level, put in two lbs shock , ran for two days took water sample down to local pool store had water tested, results perfect. 

Plaster has stains, some dark some barley noticable, appearance anwhere from light gray /brown/black to very black. Have tried most/all of the recommended remedies from various pool stores etc etc.  The stains cannot be removed by brushing. They appear to be ingrained in the plaster which is light blue. 

Is my only recourse to drain the pool and have it acid washed, and if so what do I do to keep the stains from returning. 

Thanks in advance for any advice 

Steve G

InyoRich posted this 08 August 2022

Hi Steve, I would not recommend draining and/or acid washing the pool until you know what the stains are.  I'll assume they are not organic.  I get stains from worms & leaves that sit on the bottom of my pool for a few days, but they eventually go away from the chlorine.  

I'm not a fan of algaecides in pools - especially gunite pools (some contain copper which can stain your plaster).  Try to SLAM the pool (shock level of chlorine and maintain the level) to see if that helps it.  Scrub the stains while you do this - you may need a more aggressive brush than what you usually use (like this 10" Pool Algae Brush with metal bristles).  That will remove the stains if they are algae (there are a lot of different algae out there - mustard algae and black algae are the most difficult to remove, so be patient).  Black algae can develop roots that are trickier to remove.

If that does not make a difference, get something like Jacks Magic STAIN ID KIT to see if they are from metals in the water, and then use the appropriate Jack's cleaner to remove them.  

Please keep us updated!