Return pump losing power?

[Peekay]

Here's my situation - I'm using a Jebao DCP Sine Wave Water Return Pump (DCP-5000) and when I turn it off, let it rest a few minutes, then turn it on, my overflow fills up perfectly to nearly the emergency drain. Then after about 10 minutes it seems the water level in the overflow drops to the main drain as if the return pump loses flow power. Has anyone else experienced this? What might be the causes of this? Scale buildup on the pump? Bad pump? It's a bit frustrating. Thanks

 

[ca1ore]

You sure it’s not the drain taking a few minutes to fully purge air? That’d be my guess.

 

[Sailingeric]

I would pull it out and test the flow rate in a bucket or something to see if it is dropping.

 

[jd371]

You sure it’s not the drain taking a few minutes to fully purge air? That’d be my guess.

That's what I thought as well.

 

[Peekay]

Help me understand - so as the system is purging air from the drain line (gravity fed), this will slow down the drain rate of the overflow and I should just adjust my return flow (i.e. open it up more) through the ball valve?

 

[ca1ore]

Assuming it is siphon drain air purging, you want to wait until the system completes the purge, then adjust either the drain or the pump to maintain your desired water level. In your case, it’s probably necessary to close down the siphon a bit. My system is similar. When I first start up the main pump a significant amount of water goes down the secondary. Once the primary has purged, about 5 mins, the water through the secondary is just a trickle.

 

[Peekay]

So, I decided to buy the exact same return pump as a backup. It came in today, and I swapped it out, and am able to hold the water level in the overflow just at the emergency overflow top. My guess is that I had some build up on the old pump. Currently, soaking that in a 10% muratic acid bath for a couple of days and will swap it out again should the new pump lose pumping power. Thanks for everyone's input and help!

 

[Jay Z]

I noticed on my simplicity in my salt mix tank that when all the way up it would throttle the flow back by itself after 20 seconds or so then go back to full after a couple minutes. It would just repeat this cycle. That was only on the max setting. 1 click down and it would run fine. I figured it was a pressure or heat related issues.

 

[Peekay]

I noticed on my simplicity in my salt mix tank that when all the way up it would throttle the flow back by itself after 20 seconds or so then go back to full after a couple minutes. It would just repeat this cycle. That was only on the max setting. 1 click down and it would run fine. I figured it was a pressure or heat related issues.

I wish I would have thought of that. I run my return at full power, dialing it down and opening up the gate valve a bit might have helped. If the new pump loses power, I'm going to try that. Thanks!