Question
We have a Juwel Lido 200.
The black filter box was on the right side of the aquarium; but we wanted to move it, so we removed the silicone and re-siliconed it on the left-side of the aquarium instead.
However, when we moved it we weren't careful enough about the height at which we put it; and it's a little higher than before - perhaps 1cm or so.
The heater is still submerged (and over the minimum water line on the heater); but the pump is only partially submerged now. The impeller and output are submerged; but not all of the rest of the pump.
If you look at the pictures on the Juwel website (https://www.juwel-aquarium.co.uk/Products/Filtering/Pumps/Eccoflow-pumps/), the water level covers three of the five gratings on the black box-part of the pump.
I know ideally these should be fully submerged; but all I can find on this online in general is that it "may reduce the life of the pump" because the water also helps cool the pump.
Are we likely to have a problem here - should we remove the silicone, drain our tank again and move the box down? Or will it be OK, just louder/hotter/less efficient?
Answer
The pump needs to be fully submerged - not only for cooling, but for lubrication of the bearings in the pump.
So if the pump is noisy you need to lower it or add more water to your tank. One more thing - the bacteria in your filter are dependent on a constant flow of water to stay alive.
Always use aquarium silicone for underwater use in your tank.
I added a picture of the rotor/impeller and axle, these are the parts that need to be under water.
Answered By - trond hansen