So, I'm reading a couple of other threads and came across something I may want to consider. I don't think the filter I have is going to be big enough for the tank I'm running it in (285 gallons tank/35 gallon sump). So what I am looking into is getting 3-4 20 gallon Rubbermaid trash cans, dividing them into 3 sections (mech. filter top, bio-balls in the middle and return reservoir in the bottom), putting the pump in the bottom and running a hose straight up the middle back up to the top of the tank. Basicly making a giant canister filter. I'm figuring I can get some round pieces of plexiglass and drill holes in them to separate the 3 layers.

# Assembled Depth (in.) : 19.5 in
# Assembled Height (in.) : 22.875 in
# Assembled Width (in.) : 19.5 in

Those are the dimensions of the trash cans I'm looking at. I'm thinking I will need 4 because I don't plan on filling them right up to the top. Can't go much bigger because they won't fit under the tank in the cabinet. I guess my question is, how many gallons are necessary for a 285 gallon tank? I believe I read on one of the other threads that a sump needs to be 1/4 of the tank volume. Also, how much bio-media is necessary for something like this? I'm also considering storage totes instead of garbage cans. I'm figuring I need 72 gallons for the filters. Any thoughts?

Yes, I've also read information about how big a sump filter should be, and people suggest it should be 1/4 the size of the aquarium. However, you search the Internet and see if you can find any information that explains exactly why this is, I as of yet have not been able to find any information whatsoever.

I actually think the volume of the sump filter if not quite as important as what is actually in your sump filter. People normally use some filters so they can increase the amount of media the system has on it. You can also hide all your equipment such as pumps and heaters. I have got a sump filter on my 300 gallon + aquarium. When you actually add up the dimensions it comes to less than 75 gallons, however the amount of media it holds would easily serve a system containing over 3000 gallons of water.

Until you actually get a sump filter you want realize how much media it swallows up.

I don't think you really have to have a sump filter that is exactly 1/4 the size of your aquarium. I would say a 50 gallon some filter would be perfectly adequate. If you are going to go to the trouble of installing one of these filters, you might as well do it properly. Put in lots of different types of mechanical filtration. It will contain two, may be three different types of mechanical filtration, these will consist of brushes and sponge filtration. We are also contemplating making one of the compartments a wet dry system just to make the whole filtration that much more efficient.

I have seen people install sump filters and put in thg bare minimum filtration and, what is the point of going through all the trouble if you're going to do this?

Just my opinion

Well, what I'm looking at and thinking of doing is getting 2 22-25 gallon totes. Put one on each end of the tank with a 1000 gph pump in the bottom of each one. I will mount a bulkhead on the bottom side of the tote and pretty much fill the tote with bio-balls. I will have foam rings in the overflows as a pre-filter and will have another layer on top of the tote above the bio-balls. I'll put another bulkhead on top of the tote mounted into the lid to feed water into the filter. I think this should be sufficient. This should solve my problem of getting the filter out if I need to. I was thinking it was more important to have the gph higher as opposed to the size of the filter. I guess I'll see soon enough lol.

The reason behind the size of the sump being a 1/4 the size of the tank minimum is due to over flow. If the pump stops some water is still going to flow from the tank into the sump and unless you want it on your carpet you'll need to have room in the sump. It's far more important in multiple tank set-ups.
I have a three tank set up that I'm going to sump soon so I've been scouring the internet for ideas
I have 3 X 48 x 15 x 12 tanks on a rack so I'm going to get another 48" for the sump
It'll give me a whole of around 400 - 450 litres

Think I'm probably going to have a go at drilling the tanks as I can't find any other way for it to work other than suction / siphon and this causes problems if the siphon fails.