In case you do not have valves in your suction line between the skimmer and the pump is to use your vacuum hose. I have an adaptor for the end of the hose that plugs into the bottom inside of the skimmer where the water leaves the skimmer. I put the adapter on the vacuum hose and plug the adapter and hose assembly into the bottom of the skimmer, after removing the skimmer basket. I just let the hose hang out of the skimmer. I can then open the pump basket or remove the suction line or any thing else with no water from the pool leaving the pool. If I really need to work on the pump and filter as a whole, after plugging the adapter and hose into the skimmer, I connect the filter end of the return hose on the bottom of the skimmer. This completely bypasses the pump and filter and keeps all the water in the pool. Tis is what I do when it's time to clean it he pump basket and change the DE in my filter.