I have just fitted the second external filter to my tank.
It's an Eheim 3 pro. The other oneis an APS with UV.
I can't believe how quiet the Eheim is. I am going to buy another one and sell the APS in the classisifeds.
Does Eheim do a filter with uv and in built heater?

Eheim make filters with built in heaters, but not UV, for a very simple reason. UV built into filters is not effective - there are scientific reasons for this which I have a link to somewhere but it's related to the way water flows through. Essentially the size of UV bulb built in to these filters is too small to actually kill much if any bacteria at the flow rates the filters produce. UV is more likely to be effective when it is used as a standalone add-on, using roughly 20 watts for a 250 litre tank turning over 4x per hour (1000 lph filter). The placement in the filters can mean not all water passes the UV bulb too.

Whether UV is useful at all in a freshwater set up is questionable, even with Discus, especially with hardier domestic strains and many keepers prefer not to use it as unless you go for more expensive standalone units the benefits are negligible and the cost of replacing the bulb every few months is quite high.

This online shop has the Eheim Professional 3 Thermo Filters at a decent price, and if you look in the sticky threads at the top of the member's lounge you'll find a discount code for FK members to use with that seller.

Thanks, contacted them.

I used to have an Eheim thermofilter *sobs*
it was marvellous.
Until I crammed a nitrate removal pouch into the filter for the duration of a 2 week holiday (as I would be missing a weekly water change). This caused the filter to leak slightly while we were away, and as the filter sits in a washing up bowl inside the cabinet, water built up around the base of the filter and shorted the heating element - can't be fixed, although it still works fine as an ordinary filter - beware!

I thought my APS one was fairly quiet... you can't hear it if you have the TV on.. and barely when its off. In my current situation I can't justify spending an extra £100 to get some which does the same job.. :(. But then I'm sure my APS one will die once the warranty is up!

IME the heating elements on eheim externals break very quickly, personally wouldn't bother with the thermo ever again

the filters are amazing though