Feel free to join the Seahorse Singapore Facebook group with lots of information organized in various topics which can be useful for Seahorse Keeping:
https://m.facebook.com/profile.php?id=415347352226203&ref=content_filter
you need to get a DC pump with SINE technology...... cheapest one is Jebao DCP pump, cheap and good. You can opt for the DCP5000 or 6500 for your 4ft tank which is less then $150