I have a Hayward sand filter for my pool.When I turn the control to backwash,nothing comes out.No backwash ,no pressure

SOURCE: No green comes out in backwash

Alge will quit often go through filter so first you need to kill the alge by super chlornateing the pool. You can take a water sampel to your pool store and give them the size of your pool, they can test your water, for nothing in most cases and recomend what you will need for this. Then you can start cleaning the mess up as the dead alge will turn to dirt. This dirt will be very fine and may go through your filter also so a cup full of D.E. in your skimmer after backwashing will usually coat the top of your sand and catch much finer dust and dirt. Do this as you clean the pool and backwash 1-2 times daily till clean. Follow all directions given to you at store to kill the alge first, this is very importiant.

SOURCE: I have 7 year old Hayward ProSeries, S-244S, H/R Sand filter. I've notice that when I vacuum the pool, dirty water returns to the pool. I've backwashed and the spider gasket is fine. No sa

sand filters only have limited filtration. If the dirt is very fine such as dead algae, it will go right through the filter. Use a clarifier to help give the filter finer filtration. Do not vacuum until you can see what you are doing, then vacuum on 'waste'

SOURCE: My new Hayward Pool Sand Filter won't backwash.

Hey!
Mine was doing the same thing. I had the hoses switched up. I had the hose from the pump connected to the port marked RETURN (on the Hayward vari pump valve). Not good! I also had the return line hose (from pool) connected to the port marked pump. It happens! The problem is I tried EVERYTHING ELSE before I found my error. This includes a trip to Leslie's to buy a brand new multi port valve (good thing they have a return policy) AND changing out my relatively new sand in the filter AND taking apart the vertical tube and each individual flange at the bottom to clean them out. Please check your hoses FIRST if it won't backwash! By the way...I've been a pool owner for 17 years. I think my experience worked against me since I didn't recheck my work at setup.
NOTE:
It might SEEM like your filter is working because you get suction at the skimmer and water rushing thru the return line into the pool. It's not working if your lines are backwards like mine were! My water started turning green!