Im building a very small (2.4gall uk) freshwater, planted tank, and thought that having a small internal filter could knacker my plants and therefore wondered if there was a way to diy a very smally external filter. Many thanks mattb22
I think making an external would be more trouble and cost than it's worth, TBH. There are a few non-internal filters for tanks of that size- George Farmer and others use these (http/www.aquatics-online.co.uk/catalogue/aqua-vital-hang-on-filters.asp) which, at about £10 once postage is added isn't a bad price. Eheim also make HOBS, but I'm not sure what they're like. There's only one small external I know of and that's the Eden one, available on Ebay only AFAIK, but a bit pricy.