Hi! I'd like to ask if I can keep two frogs in tank with following dimensions: 74cm x 29cm x 35cm(29,13" x 11,42" x 13,78"). As You can see, the dimensions are very close to 20L gallon tank(19,84 In fact). I've read that in 20L I can keep 3 ACF. Is it truth?

Another thing is filter selection. I can afford only HOB filter, but I don't know if it is good choice because of sand substrate. Frogs will put up the sand into the water column and I don't want it to be sucked by the filter. Anyway, better will be filter with flow 1200 litres per hour (317 US Gallons) or 800 litres (211,34 US Gallons) Both have very well-regulated flow so I'm about to buy the first one. As filtration media I intend to fill the whole filter with bio-cermics and put some prefilter to the sucking tube. These filters are produced by quite good(in my opinion) Polish firm and their names are: AquaEl FZN-3 and FZN-2. I don't know if they are available abroad.

What do you think?

PS. I think that my post was understood completly. If you can't understand sth, just tell me and I'll try to clarify it.