Hot Tub Helper

Hot tub chemistry sounds simple until you're standing over the water with four test strips, a sun-bleached chart, and a cabinet full of chemicals with names like "pH Up," "pH Down," "Alkalinity Increaser," and "Non-Chlorine Shock Oxidizer."

I built SpaSync in Lovable — a full web app with three tabs: Test, Dose, and History. I fed it my hot tub's specs (a MIRA GH72P-NL, 375 gallons), the complete owner's manual, and the full chemical list from the pool store with each product's active ingredients and concentrations.

Now I run my weekly test and enter the readings — pH, total alkalinity, chlorine — and the Dose tab tells me exactly what to add and how much, calculated against my tub's volume. The History tab tracks every reading over time and charts the trends so I can see when something is drifting before it becomes a problem.

The first time I used it, the water hit its targets on the first pass. That had never happened before.