Newbie needs help - what are isolation valves?

[xnightowl]

I'm planning to clean my Jandy DEL 60 filter. Reading through the manual the instruction after "open air release valve" says to "close the filter isolation valves on the system to prevent flooding." What are these valves, what do they look like, and where are they located? I have an IG pool and spa with a spa spillover and 2 sheer descents and with all Jandy equipments: AquaPure SWG, No-Lox heater, 2.0hp pump.

Also, what does it mean when my PSI only dropped from 20 to 18 after I backwashed and added more DE? How long does it take to backwash? This is the first time I backwashed (new pool since Mar '07) and most of the DE was flushed out in about 30seconds. It didn't seem like there was much there from what I can see on the ground. The rest of the water that came out was mostly brown dirty water but no DE that I can see. I start and stopped the backwash process about four or five times for about a minute each time. I couldn't get the water any clearer than that. Now I'm thinking that clear means pool-water-clear so I think I need to open the filter and see what's inside.

Thank you for your help.

 

[JohnT]

Isolation valves are usually installed when the equipment is installed below the water level. They keep the water from flowing out of the pipes when working on the equipment. If your equipment is above or at the water level, you probably don't have them.

 

[xnightowl]

Thank you John T. My equipment is above water level.