Filter needs backwashing almost every 12-14 hours?

Last week I setup an Intex 24'x52" pool with the SX2800 filter.

On initial setup, I put roughly 70lbs of sand to get to the middle between max and min on the filter tube. 

I backwashed until the water ran clear. Then rinsed until the view bulb was free of sand. 

​I am fairly certain my setup of the hoses is correct - 2 pump inlets come off the side of the pool into a y-pipe, into the "pre-filter/strainer bucket" which goes into the pump, out of the pump, into the side of the sand filter barrel when then runs back to the pool side outlet. 

My filter will run strong for about 12-14 hours or so and then flow will drop to almost nothing. 

A quick 30 second backwash will result in roughly 3-5 seconds of "sand colored water" being exhausted out of the drain port. I will then follow this with a 30 second rinse cycle to clear the view port of sand, and the pump will run very strong for another 12-14 hours or so before flow will again drop to next to nothing. 

I have triple checked my connections and cannot find any leaks. Pre-filter chamber stays full with a very small bubble in it.  

Pool chemistry seems decent enough. Water has only been in the pool for about a week. We have no algae issues. 

Is this normal? Are daily 12 hour interval backwashings just common for this pump/filter setup?

If not, what am I doing wrong?