First off those dimensions are incorrect for a 125gal. Standard 125 g LxWxH = 72 x 18 x 21 inches or 6'x1.5'x1.8'
A 6ft x 2.5ft x 2ft tank 'assuming' the width is 2' equates to a 225gallon aquarium. So if you have measured this tank and these dimensions are indeed correct you have a /\/\0N$T3R TANK!
Sorry for the minor derail I just wanted to clear that up because filtering a 125 or a 225 is a massive difference!
If I were you I would go with Cobalt PH, cheap price and solid:
http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=24144-Great prices and free S&H! They are made to fit sponge filters, Skimmers, reactors etc.
OR you could do what I did:
Tee'd two air outputs into one that goes to the same sponge filter and man is it powerful, relatively cheap airpump and you can adjust output. Just an idea.
On another Important note you definitely want one of those sponge filters running on air that way if you have a power outage you can hook up a battery powered airpump
http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=3693 Not only will it circulate water but since some beneficial bacteria will be housed inside the sponge it will help with ammonia~nitrate conversion. I have my airpump hooked up to a battery backup unit made for computers, bought it at goodwill for 5$ and it keeps it running full blast for almost 24 hours, if I dial the pump down to medium sure I could get 36 hours.
Or if you got the money here's a good suggestion
http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=8120
Pretty Rad imo but whatever way you choose to go I wish you the best and I hope it is a 225

:beer::beer:
×Go S Vettel #1 Infiniti Redbull! 3x WDC!!!×
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Cheap way to decrease nitrates and keep your fish healthy:
[url]http://monsterfishkeepers.com/forums/showthread.php?t=504763 [/URL]