Hi
@Anthony81 I'm assuming you're aiming for the 10x turnover rate 'rule' often quoted?
I thought I'd have a quick look at the filtration that comes with it first as I'm not familiar with it so please bare this in mind, I'm just trying to offer suggestions that might help. Good circulation is just as important if not moreso than turnover in an aquarium and it seems that your filter just has a small outlet nozzle which I think you will struggle to get good circulation from.
A couple of suggestions that may or may not work:
-measure the outside of the nozzle from the filter and see if making a spraybar is something you could do which would then run the width along the back of the tank, this is about the best way to get good circulation in most situations. I could help advise you on making it, sourcing products etc - assuming there isn't one that just slides on.
-on top of the above you could (assuming I'm right - first time for everything!) simply upgrade the pump in your filter
this
compatibility chart shows the Eccoflow 1000 is *compatible with the Lido 120 so assuming this means the Bioflow Filter M then that's your easy answer topped off. I'm assuming it's the 'M' filter housing the 1000 pump is compatible. I hope that makes sense? If not ask and I'll try to explain better. This second part is also maybe an optional if the spraybar alone isn't sufficient.
Alternatively think about external filtration if you are going down the CO2/high tech route which would give you more space in the aquarium for plants, a simple inlet nozzle and the output to a spraybar would be my suggestion for the best circulation too.
Either of these
should do away with the need for an extra powerhead on top of filtration.
All of this is just my input/opinion so doesn't mean it's right.
Let us know how you get on
Andrew