I too made the mistake of buying a couple of tiny powerheads for my fry-tanks, and a load of heaters to replace my ancient ones.
the powerheads were quite silent the first few weeks.
Now they're not so silent anymore, and NO amount of clearing the sponges or the moving parts will make them so.....
the heaters ALL produce different temperatures, despite having the same wattage, turned at the same temperature, and so in.
Highly irritating!!!
IMNSHO it's rubbish; ripe for the bin.
as Buzz so eloquently said:
Sometimes you get what you pay for
couldn't say it better myself; it's trash. cheap, they soak up twice the amount of electricity a similar sized Eheim does, noisy etcetera....
do yourself a BIG favour: stick to quality.
Although I'm Dutch myself, I have to say: Dutch industry does NOT produce anything worthwile for the aquariumhobby, especially not mechanics (internal Jewelfilter anyone?
![Rolling Eyes :roll:](./images/smilies/icon/rolleyes.gif)
), save from good medications, filterwool or carbon.
Stick to the German-made "grundlichkeit"; stuff like Jaeger, Eheim and the like, and you will not be disappointed. French stuff like Rena is also good.