Suggestions For 2nd Tank

As much as I like MA, I would not get an AquaTropic tank again.
Although the dimensions are similar to those you mention, and they are reasonably cheap, the section at the top that opens is quite small. It is fine for feeding fish, but makes tank maintenance quite difficult, and I had to resort to removing the lid completely whenever I needed to syphon the tank.
https://www.fishkeeper.co.uk/product/aquatropic-80-aquarium-set

Will your second tank be in the same room as the first tank? If so I would suggest getting the same brand of tank/cabinet so they match.
If not then I find the Fluval Roma tanks easy to use.

Don't forget to have a look at some second hand tanks, you may find a bargain.

I've also got a Fluval Roma. Mine has a drilled bottom - I don't know if Fluval still do those. I can't decide if the drilled base is a good thing or not. It is good in that the pipes are pretty discrete. But there is no flexibility on their location.

I also quite like the pipe seal on the cannister filters. I'm not going to jinx anything by directly mentioning the reliability, but I've had my tank 8 years.

Again I can't decide on the cabinet. It looked good when it went in, but we've upgraded the furniture in the last 8 years and it no longer fits in quite as well. But the cabinet doesn't have a complete back and that makes things easier for cable access.

I think getting a bigger 2nd tank is a no go, mainly due to the boss but also tanks will be upstairs and want to watch weight.

Is there any make of tank which is best to avoid?

A little off topic i know.

Just a quick note when buying a second hand tank' those of you who don't know make sure you have a suitable stand to hold the tank as many insurance company's use this as a loophole and wont pay out if it leaked.

I know Lloyds are one as i am with them and was told this when i notified them i had a fish tank.

My only one problem with the tank was the access, which may have also been due to my lack of height.
If the access section at the front had been just slightly bigger I would have been more than happy with it. 

The 50 litre tank I used to have came with a smaller version of this filter; I didn't use it because the tank replaced a 60 litre tank that had sprung a leak and I already had a fully cycled filter from that.

But the filter looked a good one. The media was just sponge, but this is one of the best media for both mechanical and biological filtration. However, I would go with the 200 not the 160. On paper the 160 looks powerful enough but even on maximum it has 500 litres/hour turnover. The 200 has a max turnover of 570. And the instruction manual does say

By pulling out or pushing in the output nozzle, the performance of the pump can be regulated for maximum or minimum efficiency. The flow direction can be set within a range of ±90°.

so it does not have to run at max turnover.

You would need to insect the chip. If it's above the water line it's not a problem but lower down it would depend on exactly where and how deep. For example, a chip right on the corner could leave just a sliver of glass coated with silicone.

You'd need to physically see the tank yourself to make your mind up. If the advert calls it a "slight" chip, well... what does that mean? 1mm in diameter? 2-3mm? Larger? Not only the diameter, but the depth needs to be seen, too as a small chip in size might run deep into the glass.

If you can't see it when the tank is filled it's probably on the inside. You can buy aquarium friendly epoxies (look for E45T or E45TM in the description) that should fill in the chip. Once cured, the epoxy will be inert so it shouldn't cause any harm to your fish.

If you've got time to fill in the chip and let it cure before adding fish, and the chip is really only cosmetic, then the epoxy should do the trick, though it would be another £10-15 for the epoxy set and I don't know how much you're saving on the tank in the first place so it may not be much of a cost-saving compared to another tank.