Vacuumed to waste/discharge, did a sand change and even a full filter replacement and the powder still returned. I have tried vaccuming this but it does not seem to be working. I am a new pool owner and I have my pool looking crystal clear, except there is white scum looking stuff settled on the bottom. The pool and heater is brand new so I hope it's not corrosion! Growing Area of White Powder "15 years ago, we had tile put down in our kitchen (wet bed) over a crawl space concrete floor. By adding these products at the same time in the same area you created a situation which prevents the calcium from remaining in solution in the water. This year there had been a huge amount of pollen in the pool, I think we have mustard algae because when you touch or brush it the pool is cloudy. The floor dried out with the assistance of a dehumidifier, the floor was cleaned, and the efflorescence was gone.Be extremely cautious when using strong acids and realize that merely rinsing them with water does not eliminate their presence. When you run your fingers along the pool in some places there is white powder residue. I backwashed prior to brushing and vacuuming the bottom and today, noticed that my psi did not change in my filter so therefore my assumption. I’ve had several pools that turn milky white and have heavy deposits of white powder resembling “flour” on every square inch with heavier concentrations in the creases 24 hours after adding, on average , 10 pounds of alkalinity increaser along with 4 pounds of calcium increaser. They said that my water though was at a high saturation index and scaling would become a problem. With today’s technology, there are epoxy-based moisture management products available. When it dries, a hard white-colored coating remains.One note: The grout most likely is not the source of the issue, but rather the residence of the efflorescence. [fa icon="calendar"] Jul 30, 2019 9:30:00 AM / by I am also a Marine corp wife, where we are currently doing a recruiting b-billet. Fine debris such as dust, sand and dirt is carried into a pool on the feet of swimmers or … A white powder could be many things. You can post now and register later. The water is kept at 84 F. My own belief is that calcium did precipate out of this. Is the residue soft and powdery or hard? My comment to them was that instead of shocking, wouldn't it be wiser to kick up the swg a little bit. If the floor did not have the appropriate vapor barrier installed under the concrete when it was poured, you may not be able to stop it. I am not an expert on plastic floor tiles, but what has occurred on your floor is the result of sealing the floor with a non-breathable covering. In this example, defective roof flashing led to excessive moisture, which in turn caused that ugly white powder on the grout joints and tile.In another situation, the problem could be the result of moisture from the soil under a basement floor or wall and might require a vapor migration membrane instead.The important point is to find the source of the problem and solve it so efflorescence doesn't reoccur. My areas are teaching chemistry & Biology at Secondary & University levels. Normally, these residues can be washed away with a very mild acid solution and a bristle brush while being careful not to harm the stone (always test first to be certain the acid will not alter the existing finish). There has to be a recent moisture intrusion into the wet bed (mortar or mud bed). Yes, I do use a heater (325000 btu Jandy Lite2) as I live in Canada but the summer has been gorgeous and the heater was mainly used in May and up until the middle of June. Attempting to clean it with a dish detergent was a good idea since most of these products will break down cooking grease and oils. Ironically, their analysis of the water showed the exact same calcium hardness number (190) both before and after this episode.