Arise dead thread and live again, muahahahahaha... er, yes, moving on.
In case anyone is interested, I finally got round to replacing my dead Aqua Gleam filter and went with the 11litre Daqua one filled with MB-115 (link in the OP) in the end.
Here it is next to the Aqua Gleam for a size comparison;
Just a bit bigger...
I ordered it late on Sunday night and it arrived the following Tuesday morning, so the service from Daqua couldn't have been better.
So, tested it out today; TDS readings - on the right is water straight out of the tap, on the left it's from the filter;
That'll do me.
A couple of things to note; the Daqua filter comes exactly as seen above, there's no hozelock connectors to attach it to the tap/hose like there was with the Aqua Gleam (which also comes as seen above with that little bit of hose and the two connectors), so if you don't have a couple spare then you'll need to buy those separately before you can use it properly (not forgetting the length of hose between the tap & filter of course).
Also, I discovered the first time I used the Aqua Gleam filter that it builds up a bit of pressure so when disconnecting it from the tap I experienced what what Debbie must have felt like when she visited Dallas, namely a face-full of fluid. The Daqua filter, being bigger, builds up much more pressure so when you come to disconnect it remember to turn the tap off but let the water flow for a bit before disconnecting anything, especially if you're using a spray gun or have it connected to the pressure washer.