hi how much does a external filter rrp for in england or a under gravel filter rrp for can sommbody help me im only 14 does any one no witch one i should go for or withch one is better

Personally speaking, I would go with the external filter.....not that UG's don't work, it's just hard to keep them clean.

I don't know what rrp is, is it anything like gph (gallons per hour????)

i realy dont know what those mean i would just go with the most powerful or most expensive one

I have 2 Eheim and their Recommended Retail Price is £65 each.

I found this - http://www.aquariumsuperstore.co.uk/mall/eheimecco.asp