Tabs in the skimmer
Trichlor tabs are acidic. Sitting in a skimmer, they dissolve into a concentrated, low-pH slug that runs straight through the pump, filter, heater, and salt cell every time the pump starts.
That is how heat exchangers corrode and why some equipment fails years early. Use a proper feeder or a floater, and count the stabilizer those tabs are adding — because they are.
Routine acid washing
An acid wash removes a layer of plaster. It is a legitimate tool for a badly stained or scaled surface, and a terrible habit as a periodic 'cleaning.'
A pool that needs acid washing every couple of years has a chemistry problem nobody has addressed. Fix the water and the surface stops needing rescue.
Shocking at noon
UV destroys free chlorine fast. Shocking a pool at midday in a Texas July wastes a meaningful share of what you just added.
Shock in the evening with the pump running so the pool holds the level overnight and does the work.
The rest of the list
Adding stabilizer 'to be safe' without testing. CYA does not leave on its own.
Backwashing a DE or sand filter weekly out of habit. It wastes water, dumps media, and never removes the oils and fine debris that actually load a filter.
Turning the pump off during a heat wave to save money. That is the exact week the pool needs circulation most.
Brushing only the floor. Waterline, steps, corners, behind ladders, and the shady wall are where algae starts.
Ignoring the filter pressure gauge, or leaving a broken one on the tank. It is the cheapest diagnostic instrument you own.
