Fluval Vs Aquaone Power Filters.

[polerz]

I need another 200L worth of filters. I have a 640L tank and I am unable to use a cannister filter as I have no where to put it. I have already two internal fluval 4 power filters running with only 4 fish in there. Its a new tank so I think I have a little bit of time before I need some more filters?

Questions:
a) how much time do I have? The ammonia is at about .25-.5ppm (but its a new tank -around 3 days old- so thats acceptable atm.). PH is spot on.

B) The two fluval 4s will cover the filtration needs for around 400L of the 640L tank. So I need another 1-2 filters to do the rest of it. I was looking at these:
2 of these:
http/www.theaquariumshop.com.au/shopexd.asp?id=189

or the much more expensive fluval ones (around $89 each).
1 of these:
http/www.theaquariumshop.com.au/shopexd.asp?id=386

My question is, whats the difference between the aquaones and the fluval. I mean they are a simple design, sponge, bit of air pumping water through the spunge.

Am I right with the aquaones? Or should I spend the extra money and get another two fluvals ontop of the two I have.

c) Are there any differences between internal power filters like the ones above or external power filters like: http/www.theaquariumshop.com.au/shopexd.asp?id=372

Thanks alot guys

p.s. the tank is cold water, I have about 4 gold fish in there.

 

[Ginge]

If you are going to buy from this websit i would say.
http/www.theaquariumshop.com.au/shopexd.asp?id=741 x2
or http/www.theaquariumshop.com.au/shopexd.asp?id=377 x2

 

[polerz]

If you are going to buy from this websit i would say.
http/www.theaquariumshop.com.au/shopexd.asp?id=741 x2
or http/www.theaquariumshop.com.au/shopexd.asp?id=377 x2

I cant use a cannister filter, its impossible to place it where my tank is situated.