Once I got my overflow box running correctly, I have had zero problems, but I wish I had a drilled tank. All a matter of money, and if you can get it drilled. Most shops won't gaurantee your tempered glass bottom against breakage when they drill it.
I dont know whats in cluded in your etc so i will jusr make it up
DSB = Deep sand bed this is the subtrate in the bottom of the main tank it is around 4" deep and does the job of filtratio there are thousands of little critters tha remove wast and bacteria tha removes the nitrate.
Sump = Basically this is just an extra tank (or any fish safe container) underneath the main tank in it you can place most of your equipment in so its out of the main tank
Refugium = Is a sump with a dsb in it many people will have organisms in there refugium that aid with filtration/ nutrient export.
Protein Skimmer = This removes alot of the pollutants out of the water that are bad for marine livestock
just to recap a bit as i've not been around long,
i have just added 25 kilo of oolite sand, which gives me a sand bed of about 2.1/2" to 3", in places, as i didnt take the rock out, just tried to spread it around as best i could (the tank is occupied)
will this be sufficient once its seeded, or should i add a bit more.
i wanted it for decor more than filtration, i rid my tank of all its sand a while ago, cos i had a really bad cyno prob, but the wife and kids kept saying it looked bare (sigh). i have about 50 kilo of l/r atm but will be adding another one or two box about xmas time
to cope with filtration, i believe this is called the "berlin system"