ok so i have a 75 gallon tank that i am planning on putting in an oscar, a green terror, and a fire mouth. What would be a good filter for them. im thinking about getting a fluval but im not sure which kind of filter i should get. im thinking anywhere from a 205, 305, or 405. and also can you say how many i should get to keep the water clean and healthy. thank you.

if you are thinking of a single filter you want a minimum of a 405(400L rated) or a pair of 305's(300L rated). an even better option is a pair of 405's or a single fx5. if it was my choice on a 75g i would have 2x405's.

The 305 and the 405 have the same flow rate anyway...it may say its 100 litres more but that's bullshit. Take a look at the pump and voltage specifications on them they are Exactly the same.

I say this because Two 305s would be the cheaper option for you

STAFFIE wrote:


this may be the case but the 405 has more media thus it can filter a bigger tank!!!

The bacteria occupy about 99.9999% of the tank anyway..Its not worth the extra 30 quid compared to a 305 for a couple of handfuls of plastic media/space is what im saying...

Two 405s would be an extra 60 quid compared to two 305s ...for little or no gain.

Most of the bacteria live in the filter, and if you have more media you can have more bacteria

It depends where you get your filters from. I just checked ebay and the price difference is about £14 each. I would always buy 405's over 305's. It gives you more media and thus filtration and if you ever upgrade a little you dont need to buy a new filter

Plus it gives me more room in my cupboards

And there is a hell of a lot of bacteria in your substrate depending on what you use...

do you think i could put play ground sand in their tank or would gravel be better

Sand or Gravel is personal choice. Some love sand, others love gravel. If you go with either just make sure you rinse it REALLY really well!!!!

Thomas112393 wrote:


x2 with Nicki... personal choice

I started with sand (sump filter though) and had lot of issues with sand in my filter material. It was a "challenge" to clean too. You don't want to suck up the sand but you need to clean it. You have to rinse the heck out of it and when you first put it in the tank, it still makes it cloudy. It can take a few days for it to settle. Mine eventually started to turn black underneath and I didn't like the look of it. I'm sure that had to do with bacteria/bioload stuff. I have since gone back to gravel. You just can't syphon sand like you can gravel. My Oscar likes to move the rocks around too... gives him something to do!! In the sand, he just made deep craters with his tail... I could see the glass bottom in some spots!

wow that really sucks. i just like sand because it looks a little more natural to me but if that black stuff that you were talking about shows up i might consider going to gravel.