A good tip for dechlorinator is to buy Pond Dechlorinator rather than Aquarium Dechlorinator. The savings you will make are immense.
Pond dechlorinator is exactly the same stuff but more concentrated, and they have to sell it cheaper because nobody wants to pay £500 to dechlorinate their pond.
I bought a 500ml bottle of 'Kockney Koi Pond Dechlorinator' from Ebay for £8. I change 75 litres of water every week, and the 500ml bottle will (in theory at least) last for just over 9 years. Beat that for value!
Pond dechlorinator all the way is my advice. Once the bottle has 'Aquarium' written on it, they charge about 20 times as much.