A month ago I read (on Polish forums) about tanks made of Optiwhite glass. It received very high ratings from customers and therefore encouraged by the price I bought one tank 300 l. The price is similar to a normal tank price. Tank came in excellent condition and seemed to be ordinary (maybe glass seemed to be darker), but after water poured into it turned out what is the strength of this type of glass. It disappeared. You do not see it and the water and the fish seem to float in the air. I was skeptical about the innovations in this area, but the effects have passed my expectations. Optiwhite glass is an excellent product.