costs

In light of the responses to my first post (https://www.fishforums.net/threads/thinking-about-getting-into-fishkeeping-would-like-estimates-of-the-likely-costs.480202/), as well as some further research, I've been able to nail down what I might start with if I get into fishkeeping slightly more...

In some other posts/ forum things i have mentioned that i am looking into upgrading my tropical tank from a 90litre to maybe a 240litre tank. i was just wondering if anybody knew how much it costs in running i.e. for the electricity per month. Bit of a weird one but any help would be great Thanks