Overflow Box

Morning I'm thinking of switchibg to an overflow box n sump set from cannister filter..  preferably not having to drill holes in my tank but not a massive problem if i have to... looking for suggestions what to go for.  Its for 500 litre freshwater tank.. oh and pump suggestions would be grateful to !

Tia...

I used to have a freshwater planted tank with a sump but I had to replace it.
I did consider a tank with a sump as a replacement but I couldn’t justify the initial outlay.
After a couple of months I did look into purchasing a sump and the overflow kit you mentioned.
There are 2 types of overflow kit (internal and external). I only looked at the external type but found I couldn’t accommodate one as they are quite big.
AllPondSolutions have a sump and overflow kit that I originally looked at. This would give you a basis to explore further solutions if required.
To give you an idea the sump I had with my original tank (250 litres) was about 75 litres in volume. So you would probably need twice that (150 litres) or bigger if that’s feasible.
For the return pump you would want a turnover between 5-10 times the volume of the tank per hour (2500 - 5000 lph).
Eheim ContactON 3000 pump or something similar would probably suit your situation.