Joe Laurino on Smart Pool Water Management

Balanced pool water is not just a “nice to have” for clear water. It is the core defense against corrosion, staining, and surface damage that shortens the life of plaster, heaters, and fittings. Water is naturally aggressive, meaning it will try to reach chemical balance by dissolving what it needs from whatever is available. When calcium hardness and carbonate alkalinity are too low, the water can pull calcium and carbonate right out of a plaster surface, slowly etching and weakening it. With vinyl liners, low alkalinity can even draw out plasticizers, leading to wrinkles and premature liner problems. For pool service professionals and homeowners, using water balance targets and the LSI (Langelier Saturation Index) is a practical way to avoid “hungry water” that quietly destroys expensive surfaces. 

 

A big part of pool water balance is controlling pH and total alkalinity as a buffering system. Keeping pH in the 7.2 to 7.8 range supports effective chlorine sanitation while reducing the risk of metal corrosion. When pH drops below 7 and metals are present, corrosion accelerates and dissolved metals can later redeposit as stains. That is why heaters are often the first expensive casualty of poor chemistry, especially gas-fired units where low pH can attack the heat exchanger. Total dissolved solids (TDS), temperature, and overall water age also matter because they influence how stable the water is and how it behaves over time. Clear water can still be “ugly water” chemically, loaded with byproducts that make problems harder to manage even if the pool looks fine.  

So when should you drain a pool? A helpful guideline from public pool standards is to consider water replacement when TDS rises about 1500 ppm above the starting point, measured after balancing and after adding salt for a salt pool. This is not a perfect marker, but it acts like a warning light that the water is carrying too much dissolved material, including disinfectant byproducts and other contaminants that accumulate with time. Cyanuric acid (stabilizer) is another common driver for partial drains because there is no easy chemical way to remove excess CYA once it builds up. Importantly, draining is not risk-free. Never dump all water from an in-ground pool without knowing the groundwater conditions because the shell can float or “pop” out of the ground. Vinyl and fiberglass pools also have structural and liner risks when fully drained, so partial drains with refills are often the safer approach.  

Before jumping to an acid wash, consider a no-drain metal stain removal approach. Acid washing removes stains by dissolving part of the surface itself, leaving plaster thinner and often rougher, so it should be the last resort. A smart sequence is to start with the mildest effective treatment while the pool is still full, often using ascorbic acid first, then citric acid, and only moving to stronger options if needed. Oxalic acid is stronger and requires careful handling with gloves and eye protection. Surface type matters too: plaster is porous, can calcify over stains, and gives metals places to hide, making older stains harder to lift. Vinyl liners and fiberglass are smooth polymer surfaces without pockets, so stains often release faster and more completely. Pairing good testing, proper pool water balance, and a thoughtful treatment ladder can reduce damage, save water, and deliver better long-term results for metal staining and pool maintenance.