I have never used that particular model Tseeker, but most any PI will work in the salt water. You will have some trouble with ID-ing metals though and you will just have to dig it all. Eventually, it is possible that you could auditorily discriminate some, but you should dig it all for a year, till you really know your machine well. Many times a bobby pin or nail will double beep, but so do broken rings, earrings and some chains, how bout them apples? I used PIs (Garrett Mark IIs) my 1st 2 water hunting seasons.
Realistically, the best thing to do is spend the money for the Excal, imo. There are used ones available all the time here on the Classifieds, even though I do not recommend buying a used water detector, unless you know that it has been well maintained and taken care of, OR a closet unit. A closet unit can be great! That is the guy who buys this new detector and thinks he is going to find a treasure chest out there, when he only finds a few pennies and pulltabs, he finally loses interest and sticks it in the closet, THAT is the unit you want, and MAYBE he never sent in the warranty card and WALLA! You could probably get one for around $800. You can pay it off, with one good find, been there done that!