pump loses suction when sand filter is connected

[mikeyonker]

I have a 16 x 32 Doughboy dug down to ground level ( top of pool is level with ground) . My equipment is about 4' above pool level . The problem I'm having is when the sand filter is in " filter " position , I lose a tremendous amount of suction . I have replaced the pump with a 1 hp inground pump but , I have the original tan Doughboy sand filter , maybe 20 years old ? When the valve is in : recirculate" position , it works fine , it's when I turn it to filter position when I have the problem. Should I replace the sand filter ? Is there above ground and in ground sand filters ? I replaced the sand last year and I backwashed it yesterday until the water was clear

 

[duraleigh]

What is the psi with the pump off?

What is the psi with the pump running and in "filter"

What is the psi with the pump running and filter in "recirc".....zero, right?

Can you see air in the pump strainer basket when the pump is running?

 

[mikeyonker]

The gauge isn't working correctly , I have to replace it . No air in the basket , I've checked for air leaks at every connection .

 

[duraleigh]

I'm pretty lost without some psi readings. Put a new gauge in there and post them up.....I'll bet it helps us help you.

 

[mikeyonker]

OK new gauge - on recirculate the gauge reads 1-2. on filter it started at 17 and climbed to 21 before I shut it off. on filter it progressively got slower as pressure built

 

[duraleigh]

It sounds like you are clogging your filter with debris.

on filter it started at 17 and climbed to 21 before I shut it off.

So backwash it again for about two minutes or so and turn it back on. Does it go from 17 to 21 again?

What does your water look like?

Can you post test results for FC and CYA?

 

[mikeyonker]

hovering around 9-10 right now - I guess i need to backwash more frequently ? Water is a little cloudy