Aqualisa shower head replacement very heavy All aspects of plumbing questions and answers, help, tips and information

[PennyPurple]

I replaced the existing (non Aqualisa) cheap shower head in my apartment with a spare Aqualisa one I had from my last place. It works well but is v heavy and I'm worried it'll strain the "holder" to keep it up. So I purchased a lighter weight one, which looks like the one I had at my last place, but the threads aren't the same (this new one is longer) so it doesn't work. Aren't they all interchangeable? Is there maybe a different thread for electric showers versus normal ones and I've got the wrong one (got it from ebay). Any idea how to ensure I get the right one? Really want to buy used to save money, not new.

[PennyPurple]

PS the one I've had on a while that's heavy is Varispray. The one that doesn't fit (that I got from ebay recently) is Harmony, which seems to have a longer thread. The shower itself is a standard shower (not aqualisa) fed with hot water - NOT an electric shower - with a bog standard hose.