Newbie dilemma: Spa attached to the pool suddenly lost water

I just moved in this house with a pool. This is my first encounter with a house with a pool/spa. There is another 'pond' that also has pump and other equipment but I don't know of its purpose. I will be learning from your extensive content and hopefully become better informed to take care of my pool so it does not become 'an expensive pit in the backyard' as a coworker sympathetically put it when he heard I bought my first house with a pool.

There is a hot tub/spa next to the pool. The pool system is set to circulate every morning and I see water flowing from the hot tub into the pool during that time.

I observed a strange phenomenon this afternoon. Between 1PM and 4PM, the spa/hot tub lost much of its water and it is now level with the jets that would normally push water inside the spa as if it has drained through them.

Someone at the diychatroom suggested it is siphoning which may be logical but what could have caused it and how do I fix it?

Thank you.

Hi New;

Some years ago, I decided that this would pretty much be a pool only forum, rather than a pool and spa forum.

There are a bunch of reasons for this, but the main one was that, while it's possible to keep a pool sanitary within the limits of what people are willing to do, it doesn't seem possible to keep a spa sanitary, without requiring more maintenance than most people will do.

In other words, pools are broken and I can help you fix them, but spas are also broken and I can NOT help you fix them!

I've never felt this was the wrong decision. However, this line has been blurred from time to time by pools with attached spas, like yours. So I'm leaving your thread up.

That said, you have a piping, valving & control problem. They are very hard to troubleshoot well without accurate information. In this case, that means a set of digital photos of the piping, filters, and pumps and an explanation of how the piping works (or should work) as you understand it. Send them to poolforum AT gmail DOT com, and I'll post them.

Good luck

Welcome to the Forum!

If you can provide the pics Ben asked for, I'll do my best to tell you how things should work and what might be wrong.

There should be a check valve to keep the water from flowing out of the spa and back into the pool. The flapper mechanism inside them does wear out and need to be replaced from time to time. That would be the first thing I would check.
Your post also seems to indicate that you have an automation system with valve actuators turning the valves. It is possible that one of the actuators has malfunctioned. or the valve itself is leaking.
As both Ben and Ted said, pictures of your setup would be most helpful.