Water Dropping in Hot Tub
This is a question we received via email, and it’s a very common question with usually a pretty simple fix.
Question: Recent first-time pool owner. We have an inground gunite pool with an elevated spa. After my first DE filter backwash the water level in the spa began to decrease to the water level of the pool when the filter was turned off. I thought that the problem must be the check valve, so I replaced that, but the decrease continues. Any thoughts or suggestions?
There seem to be two reasons this happens, but first understand what’s going on here – Gravity! Gravity is causing the water to balance out when the system is off, which means the elevated water in the hot tub is dropping to match the level of the water in the pool…which means it has a way to escape through the spa main drain.
Now that we know there’s something going on with the spa main drain, we need to figure out what’s causing the main drain to be open.
If the valves are on automatic actuators, the spa main drain valve could be stuck in the “open” position, allowing the water to slowly drain back into the pool. This could be a faulty actuator, or something as simple as a stuck relay switch. Sometimes turning off the breakers for 60 seconds will reset the relays, and when turning the breakers back on, it could fix itself. If not, it’s time to have a pool service company take a look at it.
Another very common reason for this is a faulty check valve. Check valves are in place to only allow water to flow in one direction. If the check valve goes bad, it allows water to freely flow in both directions, and leads to the nightly drain of the spa. This is usually remedied by replacing or installing a new check valve.