Filtration - I am highly considering switching to a wet/dry with sump (should not be a problem with pressurized CO2) as I really dislike cleaning canisters. From what I am gathering - a single SunSun403B is not nearly enough filtration. There seems to be quite a few threads debating pros/cons of each, and I am not really looking to start that debate here, but I am looking for a 'recommended' amount of filtration. Do I have enough? If not, canister recommendations and quantity.
I run 2 tanks: a 65 gal display tank with a 20 gal sump and a 135 gal with 2 canister filters - Fluval FX6 and a Hydor.
Both have their pros and cons.
With the sump you will have to consider the following:
1. Loss of CO2 - gal to gal, I use more CO2 in the 65 gal but there may be other variables apart from filter choice
2. Overflow and related noise (with the right design you can get a completely silent drain)
Like you, my inspiration for the 135gal was @Greggz
setup. For this set up I opted for two canisters. The set up is an overkill but will allow me to keep a larger fish load. The Fluval FX6 is a monster and I use it exclusively as a filter. The Hydor feeds the inline heater, RG reactor and UV light filter.
I do not see much difference in filter maintenance: I give the sump a quick clean every weekend and a detailed clean every two months. The canisters are cleaned alternately every month.
With regards to surface skimming, I use an Ehiem surface skimmer on the 135 - works great.
As far as recommendations go: if you go for a sump, use the largest tank you can accommodate. I really like my Jebao DCT pump. For CO2, I use a dedicated pump to feed my Cerges reactor. Lot of choice for filter media.
For canisters, my choice of filters was based on reviews. filter ratings and the killer prices I got from the LFS. Having said that I have read positive things about the Sun Sun filters. Retail price of 2 of them is similar to one FX6!