Air getting into system

[GlenP]

My first post to this site, at the end of last season my pump was drawing in air to the extent that the heat pump was under performing, and the filter a large 36" Lacron (above the level of the pool) was filled with so much air that when the pump was turned off the air would blow back to the pool leaving the pump strainer empty of water it would even pop out the skimmer basket. After pouring through posts here I realised I had a leak on the vac side, so have overhauled a lot of the fitting in front of the pump (thanks for the all the tips I would never had thought about the strainer drain plug) and think I've fixed the air leaks. The pump stainer now only has a few air bubbles (the size of 6 to 10 peas) trapped under the lid, I can see the water level in the filter is near the clear (opaque in my case) lid maybe 3" or 4" down after several days running, and when the pump is off its strainer sits full of water. So hugely better, heat pump is working really well now too.

However when the pump is off there is a glugging noise in the Multi Port valve like its drawing in air? and although difficult to see I think the water level in the filter is dropping away. Should I be looking to service this valve, the backwash/waste is open to air should I put a valve on it? I have never opened up this valve before. Any ideas please?

[Denniswiseman]

Does water come out of the backwash if not then you don't need to valve it
Your suction side seems OK by your description
It would probably be a good idea to replace the spider gasket in the MPV as this is where problems could occur

[GlenP]

Thanks for the response, no water is not coming out of the backwash. Its just when the pump is off lots of glugging noise around the MPV and hissing sound of air? I'll replace the spider gasket (when I can identify the valve and find a supplier in the UK) I think the filter is a Lacron 36" and the valve 3" says SM30- on the face plate at 3 o'clock.

Should the filter be normally full of water?

[Denniswiseman]

Did you purchase the filter complete with the MPV here in the UK. If so you could go back to the supplier and identify the part. Otherwise a lot of Googling
My pool and filter came from South Africa and I have to have parts shipped in albiet they are cheaper than purchasing from here if I can find the part
I can't see inside my sand filter but I think there is an air gap