Filtration For My 4' 160 Litre Tank. New To This So Advice Appreciated.

Hi Jeff,

I would definitely use the Eheim external - Eheim is one of the best brands. With Eheim filters, the quoted flow rate is pretty accurate as they use a figure for a filter full of media; most other makes quote a flow rate for an empty filter, and the rate drops as soon as media is added, sometimes it almost halves. The manual gives two options for media, I'd go for the option with substrat pro rather than the one with sponges - but leave out the carbon sponge, use more substrat pro.
If the Eheim is second hand, check the seal as a worn seal can leak. Replace if it doesn't look in good shape. Lubricate with vaseline.

I had to google the aquatopia filter as I haven't come across that make before. I can't quite fathom out the media, but you have the filter so perhaps you can tell me  One site says

Located inside the sponge is activated carbon

Does this mean the sponge is impregnated with carbon or that the sponge has a hollow middle filled with carbon granules?
As you can probably tell from my comments on the external, I don't like to use carbon full time in a tank. It is a hangover from decades ago when the nitrogen cycle was not understood. If the sponge is impregnated with carbon, I'd replace it with plain sponge, any make cut to the same size. If it's hollow with carbon granules inside, I'd empty it and fill the hole with sponge. That's what I did with the hole-full-of-carbon style filter in my betta's tank. Other than that it looks like a good filter as it has both sponge and ceramic media, though I have found comments saying to check regularly for clogging.

The aqua one filter - I have the 101F which came with my betta's tank. I didn't use it as the flow was too strong for a betta and I already had a cycled filter from his old tank. Mine has just one sponge but yours, being bigger, has two.

I think in your situation, I would use the Eheim with substrat pro etc rather than sponges and the aquatopia provided that the carbon is removed. Then I'd keep the aqua one in the cupboard. There may well come a time when you actually do need to use carbon, and this filter is ideal. All you need is a mesh bag and some carbon granules and put this in place of the sponge.

The filters will say to replace the media every so often. The only media that needs to be replaced is carbon (if you do use it as it gets used up) and filter wool/fine white pads as they do get clogged and don't usually wash properly. Sponges and ceramic media just need to be washed in the old tank water you take out during a water change.

If the Eheim is second hand, check the seal as a worn seal can leak. Replace if it doesn't look in good shape. Lubricate with vaseline.

Rather than vaseline, which I have just learned can cause the rubber to break down, aquarium safe silicone lubricant should be used on the seal.

You learn something new every day