Went to the lfs today to pick up Harlequin Rasbora(after reading so much positive comments about them) bought ten and put them in my QT with a few of my guppies. Went online to view pictures of them and to my surprise found out I had Glowlights instead. After reading about them am kind of happy with the switch. I am in the process of installing a 240 gallon (48x48x24") aquarium in my house and plan on stocking with large quantities of small fish. Maybe 20 corys, 20 cherry barbs, 20 zebra danios and 20 glowlight rasboras now with lots of plants any suggestions?

Make sure you don't overload your qt. Most aren't ready to receive 10 fish at once, let alone keep 10 fish due to size. Of course, I don't know how big your qt is.

With a tank that size you could have 40 of each species and be fine. Wet/dry filtration?

That tank could be spectacular, and could also hold a lot more fish. People see a large tank and want to put an oscar in it. As the large fish grows, it makes the large tank look small and cramped. Keeping small fish in huge tanks makes a stream - it lets you imagine a natural habitat and watch all the interactions and movement in all their complexity.
You have a neat project in mind there. Aquascape on!

I roughed in for wet dry filtration as this is going in our new house we are currently building.
I try to keep up on the QT tank by keeping some of my male guppies in there when not in use, then do a 50% water change before introducing quarantined fish.Kind of new to this but trying to get an understanding of water quality and do things in the best interest of the fish.

Thanks kind of my thoughts exactly am hoping to get a very active tank with lots going on.

Plan for zones. Hengeli rasboras look fantastic in 'forests' - as they move through vegetation in semi-shaded zones, they are show stoppers. I would start looking for some Cryptocorynes to plant.
You should see the spawning of those fish - they become so beautiful it's hard to believe they don't burst with their colours.
We're getting lots of weird Danio species in our stores here - no glofish frankenfish or man made sports, but things like Danio kiyathit, as an alternative to zebras. We don't have petsmart type stores, so that may save us from the usual dull selection, but these oddities are cheap and commonly available outside of the chainstore zone.
The Rasbora and Danio families are really worth exploring - there are a lot of uncommon and beautiful fish there.

I agree, sounds like a wonderful tank, please start a tank build thread so you can post pics for us .

Ok looks like I have another enjoyable night of searching the web for ideas!

Plan on a diy cave wall to hide the return lines from the filter with three outlets to spread the flow. Hoping this way I can have a couple of well planted areas.

As soon as I get to that stage in the construction I will.