Pump Performance

[REX222]

I am new to the hobby and set up a 120ltr aquarium in December with approximately 30 community fish and live plants. I have aTetratec EX700 pump suitable for up to 200 litres. The problem I have is that the pump performance (flow rate ) drops off considerably after 7/8 days, the water is not circulating and the fish not getting enough oxygen. I have tried to overcome the problem without much success, there does not appear to be any blockage in the system and no air ingress on the intake, if I switch the pump off and prime it for a few minutes the flow recovers for a few days or after I have cleaned the filter it is o.k. I am quite frustrated as I am going on 2 weeks holiday soon and feel I cannot leave the set up. I have tried to contact Tetratec but they don't have a help line, I have emailed the technical help site of the supplier (Zooplus) but they haven't responded.
Can anybody help?
Rex

 

[Colin_T]

Take it back to where you bought it. They might swap it under warranty.

Most powerfilters lose water flow as they get dirty. From your description it sounds like it is simply slowing down due to gunk build up.

 

[Tolak]

I agree with Colin_T, the flow rate on most filters I can think of have their rate stated empty, with no media. A little buildup of normal aquarium waste products will easily slow them by 25% from what I've seen.

Surface motion is what creates O2 transfer, if you are worried about low O2 levels, drop the water level a little, letting the output of the filter create more surface motion.