Jebao MDP-2500 not stable work

[klifort]

Hello everyone, I have a question about the Jebao MDP-2500 pump. The pump works smoothly, but sometimes it suddenly starts working strange and the revolutions are not stable ( going up and down) and at that moment the water level in the sump begins to drop by 4-6 cm, and in a few minutes the pump returns to normal (the revolutions do not fluctuate) and the water level returns to normal. It's hard to say when it happens - it may repeat twice in an hour, or it may work fine after 3 hours. There is no cyclicality. What can be the reason of it?
Regardless of whether it works at 100% or 75%.
Does not show errors.

My reef tank -
53 gallon (200l) + sump 13 gallon (50l), pvc 1” hydraulics. Height to which the water rises - 148cm.

 

[Gumbies R Us]

Bumping your post!

 

[klifort]

I'm closing the topic.
I decided to change the pump to Maxspect JUMP MJ-DC6K.

After long searches on the Internet, I reached certain conclusions and can write my review.

The pump is good and relatively quiet, only for an aquarium with a panel.
I do not recommend it for an aquarium with a sump, because the maximum height to which it raises water is about 180 cm and the diameter of the pipes is no more than 16. Especially since the instructions specify a maximum height of 150 cm, and on the packaging it is 250 cm, At heights above 1 m, the pump loses lifting power and does not work properly.