in need of advice

[patrickc22]

Hello fellow fish keepers

I have my new tank I'm setting up at the moment a slow process

I am wanting to put a undergravel filter witch is a 40 Gallon Size: 119 x 29cm

here is what I am thinking off from Hollywood fish farm

http://www.hollywoodfishfarm.co.nz/detail/view/clear-n-clean-undergravel-filter-40-gallon/m/998/

My tank is 122cm wide 45cm high 44.5cm deep and it has bracing on the bottom the photo shows it

as you can see it starts about 40mm in and stops 40mm from the sides

and if I put it in their I would have to sit forward or the pipes will be on a angel

I was wondering what I could put underneath it I was thinking sand to make it flat or just the stones they are 3mm to 6mm witch is the better option

my other question is how well do they work are they worth it

[Caryl]

Under gravel filters work very well but need to sit flat on the tank base with the substrate on top. You can't have fine substrate, like sand, as it gets sucked through.

You also need at least 5cm of substrate on top of the filter plate if you wish to successfully grow plants.

I would use UGFs in a small tank, up to around 60cm wide but not on larger tanks unless I also had supplementary filtering, or several outlets along the plates.

[hovmoller]

Agree with Caryl.

I would not use it on a big tank either. In fact I would never use an UGF for any tank. I'm not saying they are bad but there are so many other, in my view, more practical and efficient ways of filtration nowadays. For that size tank I would use a good sized external canister filter.

There are so many uncertainties with UGF's. How much flow will there actually be through the substrate? and how much bacteria will any given substrate support? who knows... and if you want the substrate layer deeper in some areas then the water will flow through the least resistance i.e. the shallower areas and that may reduced the filtering capacity but again who really knows..

They certainly had their day but I think their time on this earth is over, or should be (many will disagree with this)

If you are keen on an in-tank air driven system you could look at doing a HMF (Hamburg Matten Filter) which in my view is a much better and easier system than a UGF.

[Adrienne]

I like undergravel filters but not really for a tank that size. They do need to sit flat so would need to sit between the bracing. FYI plants aren't the best in them as like small fine gravel, the roots get down under the plate and block the flow. You also need a good thick gravel base to make it work - a thin base won't filter anything.

Your tank is just over 240 litres, I used to use a CF1200 on my tank that size and it was adequate.

[patrickc22]

I will be getting a aqua pro external filter 1200