New member here - filter question

[wardmolly]

Hi,

I have a 30 litre tank, which had a build in filter (Superfish Qubiq pro 30 to be precise), but was making a very loud rattling noise, went back to the shop and they ordered a new propeller, but noise started again. Since then, retrieved an old filter from the attic we had used previously for not a long period of time at all and made sure to clean it well (Superfish Aqua Flow 200), and has really solved the noise issue (tank is in my bedroom) pretty much! Obviously it is for 100-200litre tanks which is a huge difference compared to my 30litre, but it is on the lowest setting possible, and is moving the top surface layer of the water, but seems to not be causing any water movement under it.

I'm aware theres such a thing as no too big filter for a tank, but what are people's opinions on my current situation? To me, it looks ideal apart from the whole top layer of the water is flowing, but the fish (only currently have 1 guppy, 6 harlequins - am aware it is a small tank so won't be adding too many more), and they actually seem to be enjoying it and playing in the current quite a lot. However, I know there is a distinction between fish struggling to swim in a current vs. playing, but mine looks like the latter. Any opinions/advice welcome, am aware I can purchase the Aqua Flow 50, but my current one seems largely fine.

Thanks

 

[AbbeysDad]

Although it's parroted a LOT, the statement "There's no such thing as too much filtration" is FALSE. The Dirty Truth about Filters is that they merely aid in water clarity, but do very little for water purity. Detritus trapped in the filter decomposes to pollute the water.
Although some fish in the hobby are wild caught in fast moving streams or rivers, most are tank, vat, or pond raised and never see fast moving water. So turbulent waters in the aquarium can cause stress for many fish.
Without actually seeing it, I can't really visualize how much turbulence your (sounds like over size) filter is generating - so you'll just need to use your own judgement. However, you can often offset surface turbulence with decor that allow fish resting places with low flow.
Look here for a deep dive into Filtration and Water Quality.