Hi nini...sorry for late response... mine is 1400 x 700. When installing the bathtub, suggest u take a look before they conceal the sides, to ensure the tub is sitting firmly on the concrete they place below. This will ensure the tub does not crack on the base because of weight/pressure. this was an advice from someone in this line to me...
DIY spa... hehe, using bath salts, scrubs, essential oils... or milk bath... depending on what sort of treatments u intend to use. In fact, u can find a lot of tips thru search engines on the internet... =p