Make sure you have all of the tools and supplies you will need: basic hand tools, filter pump, drain plugs, gauges, cartridges, sight glasses, timer pins, summarizing chemicals, cover pump, garden hose, return eye balls, skimmer baskets and other accessories i.e. ladders, handrails, etc.
First you want to try to clean off the cover as best you can while it is still on the pool. This means sweeping leaves and dirt, and spraying off with a garden hose. Many times the cover will fill with water over the winter months and will need to be pumped off with a cover pump. Place cover pump on the cover of the pool and let it drain until cover is dry.
Typically above ground pools use covers that are secured by cable and winch. If so, loosen the winch to pull out the cable. If using a Loop Loc cover, make sure all spring are removed from the anchors and screw anchors back down into the deck/patio. If using a hard cover with water bags, drain out all the bags, fold them up and store them in a safe place where they won’t get punctured. Have a partner help you fan fold the cover, remove and deflate the air pillow, and store in a safe, dry location.
Remove the plate from the skimmer mouth and reattach the skimmer to the outside wall of the pool. Remove any plugs from the wall returns and skimmers, and then reinsert return eye balls and skimmer baskets.
Use the input hose to reattach the bottom of the skimmer to the front of the pump, then the middle hose from the pump to the chlorinator to the filter unit. (If no chlorinator, then attach directly from pump to filter) Then the output hose connects the filter to the return jet on the wall. Insert drain plugs in the bottom side of the filter, return the gauges and sight glass to their designated locations and insert the cartridge into the filter (cartridge filters only).
Pools with Salt-Chlorine Generators, summerize the Cell according to manufacturer instructions. Heater trays can be reinserted into gas heaters but a trained pool professional should do this work. Once complete, turn on valve for gas supply.
Fill the pump with water so it drains into the skimmer lines. When the pump fills with water, insert the pump basket into the pump and screw down the lid making sure the rubber gasket is properly aligned into the groove making an airtight seal between the lid and the pump. Once the filter and pump are completely reconnected, plug the pump into the power outlet and turn the circuit breakers back on. Start up the system and add D.E. into the filter through the skimmer (D.E. filters only). Now you can attach all accessories such as diving boards, ladders, handrails etc.
Use a chemical test kit to check the chemical levels. A heavy dosage of shock should be added to help clear up the water and add other chemicals as needed such as Total Alkalinity, Calcium, PH, and chlorine tabs. It will take a few days to balance the chemicals to the right ranges (see Guide to Water Care).
Use a power vacuum to remove heavy debris off the floor, or vacuum the pool on waste to avoid clogging the filter and lower the water level to the midway point on the skimmer mouth. Brush algae and remaining debris stuck to the floor and walls.
Let filter run for 24 hours until water is showing improvements. Backwash the filter later that day or the next morning. Do a follow up vacuum the next day and add more shock if water is still green or cloudy. The more often you backwash your filter at this stage, the quicker the water will clear up.
Continue to test the chemicals daily until they are all within range and reinsert the timer pins into the timer clock to go back on an automatic running cycle.