Bath tap 'flow straightener' restricts flow

[essayer]

In the summer we had our bathroom done and they installed a Grohe Concetto bath mixer
The flow from it has always been duff and I blamed the fact we have a gravity water set up, cold tank in the loft and cylinder on first floor etc.

SWMBO was complaining that it had got even slower - and whipped off the 'flow straightener' to find it full of gunk - like like scale but slimy.

Anyway I noticed that if I took this straightener off, the water pissed out faster than George Best getting home from the pub, filling the bath far quicker than ever before.

It restricts the diameter by probably 50% plus has a few layers of fine mesh, so no wonder we get a slow flow.

You can see it here on the diagram,
http://cdn08.grohe.com/lib/1/tpi/1590364.pdf part 46162

So the question is, are 'straight through' flow straighteners available? Could multiple ones (LP/HP) have been included with the tap and the plumber just used the wrong one?

[essayer]

bernhund said:

Why not leave it out?

Without it fitted it splashes back over the tiled area at the back of the bath.

I'll keep an eye on why there would be the sludge in it, maybe it wasn't flushed through when it was first fitted? None of the other taps have exhibited this problem.

[essayer]

Measured it now.. With the straightener cleaned out, both taps full gets me about 16L/min.
With it removed, 25L/min.

Seems like a big loss just to have 'straightened' flow !

[essayer]

As always, the OP wants a peaceful life, and the degunked straightener has achieved that so far. It would be nice to gain some small increase in flow rate (in hindsight buying a huge bath was also a silly idea)

I wonder if they are all the same measurements, which would let me swap some low pressure generic version off eBay..