I posted a question a few weeks ago on filters and everyone suggested eheim pro 2080 for a large discus tank (240 gallons). Question the eheim pro is rated for a 400 gallon tank but I know filtration is critical for discus. If I had the dollars do I need two of these to be safe?

No you dont need two of them but on that size tank it would be your decision, Ideally you need a MINIMUM of 880gph of water turnover(filtering).
On my 210 I use the 2080 as well as a sealife systems aquapro400 with twin model 12 mag drive pumps. I clean the eheim ever month and the wet/dry sponges every week.

If you have the cash for two, go for it you will not be displeased at all.
I also found that extending the spray bar cuts back on the pressure coming out of it as well, it used to blow my discus around when they got close but I attached 3 more sections and no more just a nice steady gentle flow.

Not cheap, no matter which way you go. Big tanks = big money.

i was told about the eheim pro 2080 as well. for my 135 gallon set up. unfornitully i had to break down the tank b4 i bought the eheim

I built my filter for my 240 gallon (drilled and overflowed) tank. I think it is better than any I could buy and I built it for that reason rather than price. If I had pictures posted I would show you. This is my second generation of the same design because the first one worked so well. I used the first one on a 110 gallon tank that is now my sump. The first one was built in a 55 gallon trash can and had one stack but worked so well I refined the design for my new tank. The new tank has two “stacks” and even has a trap with a 1-1/4” hose and ball valve that I can use as a vacuum system. The water from the vacuum is returned through a fine felt bag that I take out and wash when I am through.
Each stack was made from four, five gallon hardware buckets. The one on the bottom (bucket 1) has a number of about 1” holes drilled around the outside edge as close to the base as possible. The next one (bucket 2) sets down in it like it was stacked for storage. The bottom of bucket 2 is covered in 3/8” to ½” holes. For discus I use Ehime substrate in that bucket (in a cheap mesh bag) but you can use carbon or Chemi-Pure. I placed several ½” PVC tubes inside around the edges and cut them off so the next bucket (bucket 3) would sit down about 3 or 4 inches, leaving room for the bio/mechanical section. The water line should be near the top of bucket 2 but not over the top lip. The bottom of bucket 3 is drilled like bucket 2 and it too has PCV tubes inside to hold the top section up. I cut a 3” hole in the side of bucket 3 and used plastic gutter material to extend above the sump then placed a small fan in it to keep air circulating through bucket 3. Bucket 3 is filled with plastic bio-balls and is a wet/dry arrangement. Bucket 4 is cut off (about 3 or 4 inches) so that when it sits on the PVC tubes in bucket 3 the top is just below the lip of bucket 3. The bottom of bucket 4 is drilled like bucket 2 and bucket 3. I use a felt bag on the return tube from the tank and fill it with floss to catch the solid waste. That sits in bucket 4.
I drive this with a 1200 gallon Coralife external pump but the pump type is completely optional. I used a piece of 4” gutter on the inlet and put the finest mesh 4” plastic rimmed filter bag in it to make sure nothing got into my pump. The fitting I used has a 4” opening and expands out to maybe 10” so there is free flow around the bag and the plastic rim of the bags fits like a glove and does not have to be attached. The suction holds it in place.
To top it all off I have the heaters in the sump and a small submersible pump like used for a lift tube to keep the water stirred up in the sump and to provide final aeration before the water is returned to the main tank.
I am not sure of the full benefit with discus but I used three Coralife 12”, 36 watt, UV sterilizers in series on the return to the tank.
One of the neatest parts of this is the sump and pumps are in my garage, on the other side of the wall from my display tank, so I can service the filters without disturbing the tank or having to be a contortionist to get to it, and the only noise is the gurgling of the overflows.
Since I do not use any carbon or other chemical filter I can maintain black water using Blackwater Extract and I maintain the vitamins and minerals with Discus code. I change out about 100 gallons every weekend and do all my filling in the sump but use a hose to vacuum the tank outside rather than through my nifty vacuum system.
My aquarium store probably would not recommend it because I haven’t bought fish in two years. They are healthy but some of the “slow growers” are looking old so we are contemplating re-stocking.