i've made the choice to go with Hagen products, as i've always used them without any problems. [/shameless plug]

Equipment:
-filters [2 aquaclear 70s (300 gph each -- 600 gph total)]
-heaters [2 tronic 150w submersiables -- 300w total]
-lights [flourescent whatever]
-gravel [60 lbs of small, natural gravel (i dont like sand)]
-decor / plants / rocks / roots
*maybe a powerhead [eheim aquaball?]
Questions:
1. are 2 - 150w heaters enough for a 55g?
2. should i get a powerhead?
3. will 60 lbs. of gravel be enough for a 55g?
4. i picked AC filters, but would canister filters (fluval?) be a better choice?
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Fish:
-8 yoyo loaches (i have 2 in the 10g. already) Showpiece

-2 angelfish
*maybe 2 dwarf gouramis
*maybe 4-6 hatchetfish
-some dither fish [danios, barbs, rasboras, tetras, etc.] (give me ideas)
-2 clown plecos or 1 bristlenose
Questions:
1. would dwarf gouramis go well with the other fish?
2. i know that dither fish make loaches feel safer, so they go play more, so give me some ideas on species and numbers.
3. could i get some hatchetfish to inhabit the top-level in the tank? i was thinking 4-6, but they are optional.
thanks,
brett.