Is 45mg/l nitrates bad?

Hi all,
I am still suffering from high Nitrates and have come to the conclusion that my eheim 2229 wet/dry filter is the cause, dose anyone else use this filter with success or am i the only one:headshake2:.
I have emailed Ehiem to ask the question as their litrature states they are for marine use, so why the high Nitrate output? and await a reply.
My water is spot on, all life is healthy if a little hungry no signs of algae and regular water changes keep all dirt form the tank. I now wash my fluval 304 sponges out in tap water then RO every two weeks and in this filter is only ultra-lith.
:help:any suggestions welcome,thanks all.

There are no cartridges in my 2229 just the media (substrat pro6) which seems to always be quite clean, i think it just makes nitrate:sad:

OK, i have cleaned out both my ehiem and fluval externals.Both were quite clean, the sponges in the fluval i cleaned in tap and then RO water also the canister its self + baskets. Washed the phos remover still in its bags in tank water ( quite dirty)
Washed the ehiem bottom basket of media in tank water, threw out all the small balls which had worm casts on them,and washed canister sponge and baskets in tap then RO.
I have also added a standard polyfilter to the mix in the fluval top basket under the phos remover after the ultra-lith (dose this work well in a canister?)
Just tested water stats :-
sg 1.024
temp 25.6 c
phos 0
nite 0
amo 0
Ph 8.1
KH 9dKH
nitrate 35mgl
I have spoken to both the shop that sold me the Ehiem and also a good retailer the seller thinks that my Nitrate is OK "all shops run the same if not higher its not important"
My trusted retailer wants to help me get them down but also says it's manageable.
Should i just let be?

Getting there <35 now

What do you run at Grins and how do you do it???? :help:
I originally wanted a sump on this tank but was informed not to as a juwel cabinet has been known to fall to bits because of the humidity caused mind you that was by the man who sold me the Ehime.....