I have a sunken on ground pool that has metal walls, sand bottom and liner. There is no drain at bottom. The soil is clay and there is alot of groundwater around pool. There has been barely any rain last couple weeks but there is alot of water under the liner, the edges are floating and vacuum sucks up liner since it's loose. I read to take part of liner out and siphon water.. How exactly do i siphon without using a pump? Should I look into adding some kind of a sump pit? Looking for the cheapest option but seems like this is going to be a yearly thing.