# Oase Biomaster 250



## Robert Fletcher (5 Apr 2021)

I have had a Biomaster 250 for almost 2 years. In that time it has been fantastic, easy and reliable. That is until recently when the flow was impeded and a loss of fish.
I have rebuilt the tank and cleaned every part of the filter. With some difficulty, I got it to prime.
Now I have just done a water change. I used the prime pump and water syphoned into the body of the filter. But then the air was bubbling out of the intake. When the bubbling stopped so did any flow. I did not see any flow from the Eheim spray bar outlet. Physically blocking the inlet with my figure and pumping would get the flow running properly.
I am feeling that the priming pump may have failed it just has little flap valves. I could replace this but I don't want to be wrong. Up to now it has been the easiest filter I have every worked with.
Robert...


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## orxe87 (5 Apr 2021)

I've always found primers problematic when half primed which can happen after maintenance - some water in but not completely full, hoses half full but the pump is in air so can't pull down the bubble in the intake line. You cn get spare flappy bits I think which implies they can degrade or fail - presumably they have to seal against air so need to be quite smooth, any algae or biofilm or damage might affect them. 

Raising the pump (lifting the filter) has helped, and if not then draining the hoses completely and re-priming normally works for me.

Do you have _some_ water in it? If so then if able you could try turning the entire filter upside down (I know, heavy and awkward) and turning it on - that way all the reminaing air is removed from the motor housing and it'll run OK and overcome the . Then very slowly turn it right side up until the air is evacuated. Possibly do-able with a 250 sized filter, but it'll definitely make your arm muscles hurt


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## Robert Fletcher (5 Apr 2021)

Found the problem it was the "Priming head valve seal" it was all packed with gunk. I have given everything a good clean. I will let it dry out then have a look tomorrow. I may have to go for a replacement. When it is working properly priming is just one pump. Thanks for your help.


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