Spa empties into pool when the pump is off.

One of my properties they i own has a pool and spa thats has a DE filtration system. the spa is attched to the pool an it has a waterfall effect, that when the system runs, the water flows into the pool. Also, the spa is elevated about 2 feet above pool level. My problem is that when the pump is off the spa somehow empties into the pool. but not through the waterfall. I believe the spa drain and the pool main drain are connected. I have two valves. One for the skimmer and one to the pool. I have tried moving these valves but had no luck. Ihave ruled out any leak because when i turn the system on, after about 10 minutes the water level in the spa raises to normal.

Trying to diagnose system flow problems, without exact knowledge of the piping and system involved, is not very practical.

If you want to send photos and a sketch to poolforum AT gmail. DOT com, I'll post them and we can go from there.

There is usually a check valve in the return (jet) line to keep the spa from draining when the pump is off because of gravity. That is the first place I would look. There should also be valves to isolate the spa from the pool when you want to use the spa. There might be one or two,depending on how your system was plumbed. If the valve has worn it can allow water to flow backwards and into the pool even though the valve is not turned that way.

Without seeing pics it's impossible to say more but what I described are the most common causes of what you are describing.

If your system is very simple (since you said there are only two valves)you will always have water flowing into the spa and have a valve to control whether the spa drain is open and the pool drain and skimmer closed (thereby isolating the spa from the pool so it can be heated) or the other way so water flows into the spa, spills over, and then goes into the pool skimmer and drain. You might also have a second valve to control the pool drain and skimmer, opening one or the other or both. There is often also a check valve in the return line to the spa to prevent water from flowing backwards when the pump is off (which it will do because the spa and therefore the water level is elevated).

Thanks, Waterbear.

Thanks for all the advice. There are also two valve actuators. I will try to send some pics.

Here's the pic you sent. However, you might want to take enough for WaterBear or someone to see the entire piping layout.

https://lh5.googleusercontent.com/-L....42-upload.jpg

Here's a link to a larger version: https://lh5.googleusercontent.com/-L....42-upload.jpg