Question about DIY Under Current system

I have built a 4 site under current system. I used 3 inch current culture bulkheads and 5.3 gallon square black buckets. I have a 700gph water pump circulating the water but that amount is too much for my chiller so i also have a small 290gpg water pump that runs inline and connects my control bucket to my chiller. Both the chiller and control bucket are outside the tent.

My question is, what is the proper size return hose and are inline filters absolutely necessary?

The fittings that came with this water pump are only 1/2 inch and im wondering if that is big enough and ive never used an inline filter, are they crucially needed?

 

I've never used an inline filter and I've ran single bucket DWC and had the pump in the bucket running the water thru a chiller and it never clogged. I dont think an inline filter is 100% needed but I found out that this pump will actually run a 1" hose so i was able to run a larger return hose. The larger return hose is more important than an inline filter. I think im going to make a small change after this run and make the return hose into a return pipe that is 1.5 inches and then reduce it to 1 inch to go into the pump and that'll keep water flowing easier and faster but ive had plants in the system for roughly 10 days and theyre absolutely loving it and so am I.
The pH is rock steady. I set the pH at 6.2 and its still at 6.2
This system is hands free other than filling the reservoir, LST and defoliation. The control bucket pumps and chiller being outside the tent keeps my environment at 77-78° the whole thing is actually wonderful and i wish i had done it sooner. I used to do basic DWC a long time ago without any recirculating and i loved it but ive been using coco now for ever it seems and i dont know why.