I have a davey xb 150 pump running my pool filter and suddenly it now has air in the system ( i havent touched anything),what can cause this

Use chisel to break off plastic portion, then wrench to remove remaining threaded insert.

Air bubbles in pump pots or basket filters are common and will not hurt anything. If you are saying the filter pressure gauge is reading 25lbs that is not low but high unless you have a floor cleaning system or a long run with a lot of piping.

Jason
this sounds as though there is no water going through the strainer into the pool. check the gate valves to make sure you have water going to the pump and that water can get back to the pool.
check and valves or backwash valve on the pool to make sure the filter is open to be able to let the water filter to the pool.
something is stopping the water flowing to the pump or preventing the water to move through the pump into the pool.

Rod
US Parts Center

Three areas that can cause low flow 1) the intake on the pool, if you are using the pool sweep basket feature, then undo the connection at the pool wall and you will find that the wall filter is plugs with fin bug particles that can not make it past the wall screen. Clean and replace the hose to the wall. 2) the filter is clogged and dirty, clean the filter clean the filter compartment and replace, 3) you have an air leak allowing air to enter the pump system causing air to restrict the flow of water. Check the hose connection for leakage, check to make sure the bleeder valves are not loose or over tightened, as both will cause an air leak.

Check your pool cleaners filter screen in the in-line filter system and make sure that it is clear of debris. Also check the skimmer, basket, pump basket, and pool filter to make sure that they don't have anything blocking suction. A loss of suction would definitely make the cleaner stop moving. Make sure that your hoses and connections do not have leaks that could be causing air to to escape.

If the pool filter is blowing sand and debris back into the pool, it is most likely due to backpressure. This is cause by air in the lines. You most likely have a crack somewhere in your system. Start by checking all of your connections and plumbing with your filter and pump. Then start checking your pipes, etc.

If you pressure is low on these pool filters, there are several things that you will want to check. First, make sure that your system strainer baskets are not dirty or clogged. Also, check the suction side of your pump to make sure that there are no leaks. Make sure taht you filter cartridge does not need to be replaced or cleaned. Make sure your pump is properly primed and that the pump impeller vanes are not blocked. Make sure that your strainer basket is not broken to allow debris in.

Make sure you have your tube completly filled with water. hold one end at the discharge while pump is running when full make sure both end of hose stay under water while connecting. I also leave the bleedee cap unscrewed just a bit to let air escape from the system HAVENT HAD A PROBLEM YET

check for air leaks, cover o-ring is common culprit. anything in front of pump can cause this.

we have changed the sand in our filter but now we cant get the back wash to work we have a davey tagelus 230 i need a diagraham to show how to put the muliti flow value on again