Spa draining when pump is on

We have a kidney shaped pool with an attached spa that overflows into the pool. If open up suction for both pool and spa and have both jets on the spa side tends to drain. It seems if I have enough water in the pool this does not happen. The backflow from the pool fills the spa quickly enough. The problem is the water level only holds for a couple of days.

There is usually only a 1/2 to 3/4 inch of above the overflow cut out. The spa has two drains in it. I am curious if normal evaropation might lead to water levels dropping just enough to where the flow from the pool is not strong enough to flow an amount of water = to what is being drained back into the spa or if a leak is indicated. The pot on the pump has no air if all drains are open but if I close off the spa suction the pump pot does not fully fill, it looks like there is air in the system. The same also happens when the pool suction is off and spa on.

For now I have the spa suction off with returns on for pool and spa so there is some circulaton. Partially I am doing this because if I have leave both drains on, the spa drain pulls leaves and pine straw to the bottom and my sweeper can't there. Could this be due to normal evaropation since there even a small water loss can affect the flow between pool and spa or could it be a leak?

From what you're describing it sounds like levels are critical. Where you live I would believe evaporation could be significant. Only thing I can suggest now is do you remember how things behaved in prior years? Evaporation can vary greatly year to year and season to season. Last year in early spring I chased a ficticious leak for a week only to have it stop. This year, nothing like that. Just strange combination of water temp, air temp, relative humidity and wind. Best I can think of for now.
Al

Welcome to PF!!

The way [i]we[/u] design our spillover spas is to run with no spa suction when in spillover mode. In theory, the spilling over acts like a skimmer and sends surface debris into the pool to be claimed by the pool's skimmers. The only time we open the spa drains is when the spa needs cleaning (debris can be swept into the spa drains for filtering) or we manually vacuum the spa seats and floor.

Due to the vaguerities (sp?) of each system set-up - how could you possibly be able to select "that perfect valve setting" to enable you to be able to insure that the spa won't eventually fail to overflow? :confused:

However, if it's worked for you in the past, I can only suggest that you don't ever let the skimmer baskets/ MD become congested enough to block any suction through them.

Thanks guys. I am kind of new to this. First pool. Came with the house. I think the pool has been there since mid 1980's but having only been here about 6 months so I am not sure what is normal. :) I wasn't sure if it was evaropation since temps are getting in the 90's now here in South Texas or if it was something else. Thanks for the help.

I am glad to know the design is to only run suction in the spa if you operating spa only. If I replace the heater that thas is there but been taking out of the circulation loop, there might reason to only circulate the spa if it is being heated. No heater no need for that. :)