Spa & hot tub guides

Hot tub chemistry runs by different rules than pool chemistry. The volume is far smaller — typically 250–500 gallons — so every chemical addition hits harder and imbalances develop faster. Water running at 100–104°F accelerates bacterial growth, increases chemical consumption, and drives pH up constantly from jet aeration. And because more people are in fewer gallons of water, contaminants accumulate quickly between uses.

The sanitizer choice you make upfront shapes your entire maintenance routine. Bromine is more heat-stable, produces less irritating byproducts, and recovers quickly when you add an MPS oxidizer. Chlorine is faster-acting and less expensive, but CYA management is critical — dichlor (the most common granular spa chlorine) adds CYA with every dose, and CYA builds up fast in a small volume. PoolChem Tracker supports both systems.

Both systems need more attention than a pool, and neither can run indefinitely without a water change. TDS (total dissolved solids) accumulates until the water becomes chemically exhausted. Most hot tubs need a full drain and refill every 3–4 months — sooner with heavy use. These guides cover the full spa maintenance picture.