How do you remove black stain patches caused by using a stainless steel wire brush to clean off algae throughout the bottom of a concrete pebblecrete salt water inground pool?

Answer 1

Black stain patches??? Can you scrape them off? If so, it may be black algae. But I can not see how you got black algae with a salt system if you are operating it properly. Just how long are you running the filter and salt feed. Are you maintaining chlorine levels at 1.5 3.0 or higher? If you are not doing the required maintenance procedures then you are doomed to have a poor quality pool.

For white plaster only. You have to treat with "Algban" "Algaekill" granular chlorine. FOLLOW LABEL INSTRUCTIONS!!!!

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Here's another answer. I wanted to put it here because your question is perfect. Everybody always thinks black stains are algae but if you cannot scrape off any of the stain with anything less than sand paper then you may have the same thing as my pool. See if this sounds familiar: 2 years ago we had our in-ground pool replastered and at the same time installed a salt system. The pool guy added the salt about 1 week after the plaster went in (WAY too soon, supposed to wait 4-6 weeks before adding salt). Within another week we started seeing dark stains appearing first on the bottom and then on the sides of the pool. These stains became progressively more black and slowly took over more than 50% of the white plaster. The brand new metal ring on our pool light became corroded very, very quickly. Nothing we did stopped the damage. Nobody knew what was wrong. Our chemical levels were perfect but all contractors involved blamed "chemical abuse" and walked away (smugly). For a solution we tried acid washing but nothing less than a 100% solution even touched it. We achieved about 80% reduction of stains with the acid wash but then, within a week, the stains started to darken up again until they were worse than ever. Next we tried an acid soak where we saturated the water with like 12 cases of acid and let it soak for a week (nightmare dangerous - a pit of acid in your backyard - yikes!). Don't bother. It didn't even touch the stains. The final solution? Replaster to the tune of $5,000.00! Added a pozzalan called Metamax, which is a brand name in So. Cal. Pozzalans, when added to the plaster mix, reduce chemical staining and etching by 22%. Anway, nobody is sure why we got all the staining but the best answer we have gotten is stray current from an improperly grounded salt system (ours in a Polaris). If the salt system isn't properly grounded there will be stray current in the water. Maybe you've felt a tingle when touching metal components or on the wet deck in bare feet but maybe you haven't (we didn't)? At any rate, this stray current somehow leeches the metals out of your metal components and deposits them like concrete on your plaster job. There's a guy name Greg Garrett at Applied Chemical (or something like that) in Arizona. Whenever you mention this guy to anyone in the western pool industry you hear about what a genious he is. Anyway, you can get his number if you call the National Plasterer's Council (see their website). He is the best pool chemist in the west and will come out and diagnose your problem for about $400.00. I thought that was too expensive and put it off for 2 years while I slaved away on my own trying to find answers that, as I'm sure you've noticed, don't exist online. In the end, Greg said I should try to torch the stains off (yes, torch) and then acid wash the torch marks off. It's the only thing he's seen work. Bottom line though is that you need to get an speciality electrician (see your local pool store rep) to make sure your salt system is grounded or anything you do to remove the stains is a waste as they'll return right away. My solution was to remove the stupid salt system. Beyond the staining, I learned in all my research that the salt ends up eating your pool equipment (filters, motor, heater - which makes sense) AND corrodes metal components AND eats stone surface decking AND the grout between your tiles. I certainly saw all that damage in progress so we removed it. You may want to as well. I know it was expensive but it wasn't as expensive as what you'll have to do to repair everything! Trust me. E-bay that sucker before everybody finds out how screwed up they are and it's worthless!