Not to nitpick but there is no such thing as a day trading account. It's either a Cash Account or a Margin Account. If you choose to day trade, each type of account has its own requirements/limitations for such trading.
In the US, a Pattern Day Trader (PDT) is someone who executes more than 3 day trades (options and equities) in a rolling 5 business day period in a margin account, provided the number of day trades is more than six percent of the total trading activity for that same five day period.
A PDT must maintain a minimum equity of $25k in a margin account on any day that trades are made and must be in the account prior to the day trading. If the account drops below $25k, no day trades will be allowed until the account is restored to the $25k minimum equity level.
Day trading is defined as the buying and selling of a security within a single trading day. If you are buying at close today and selling at the close tomorrow then you are NOT day trading.
Practically speaking, a minimum of $25k is needed to open an account but you need a bit more because A PDT must maintain a minimum equity of $25k on any day that trades are made. It must be in the account prior to the day trading. If the account falls below $25,000, the PDT will not be permitted to day trade until the account is restored to the $25,000 minimum equity level.