Good point. I thought about that, but it's not cost effective, because I would have to use a lot of bottled water. So, I don't feel I have any choice but to rinse it with tap water (25-30ppm Nitrate). I know that rinsing it out as thorough as I do after a re-charge, I am already adding to the total nitrate burden for the freshly re-charged resin. When I leave it in salt solution for 2 hours, or overnight, I will use water that the resin has already partially "de-nitrated", but that still leaves in sitting in water that is 5ppm (at least), but I think less than 10ppm nitrate.
Unless I am missing something obvious, and not thinking straight, I can't think of a way to rinse it in nitrate free (or nearly free) water. Well, I could use bottled spring water which comes up as nearly undetectable nitrate on the API test, but it would be a significant financial impact, because I am re-charging the resin most days, and I like to rinse out the resin bag REAL thorough to make sure all the salt is off.
All this faffing does take me closer to moving to the RO/Tap option, (I live in hard water + high nitrate), because my dream is to get more into dwarf cichlids like you. Well actually, German Blue Rams are first on my list, followed by some of the smaller Acara species. But I will be moving home in anything between 3-6 months time, and don't want to mess with the plumbing yet, and there is the cost of RO waste water to consider.
Consider this is a bit dumb, I don't blame you, but I am not too keen on nitrate filtration that involves anything to do with plumbing right now, no matter how straight forward it might be. I am also not to keen on adding nitrate reducing agents to my tank directly, perhaps paranoia, perhaps sensible? There was a good review by
@MaloK on here about Tetra Nitrate Minus, I think it was
@MaloK
I heard good things about Seachem Matrix, I mean proper geeky (which I love) reviews on other forums, not just gossip. Matrix is marketed toward the whole nitrogen cycle burden, but apparently, the media design is very receptive to nitrate reducing bacteria, regardless of water flow levels through the filter. Seachem De-nitrite, I believe, relies on slower flow.
My plants I have been ordering over the last month are mostly all taking off, quick growers like hornwort, salvina natans, najas grass (think it's still settling in, deciding if it's going to flourish), hygrophila difformis and some elodea densa (think that might be on the way out, although it might now be adapting to 74 F). I've also got some pothos in one tank to see how I get on with that. Early results on nitrate levels, the jury is out, possibly too early. As things stand, I think I might just fall in love with the hornwort, as I like the shade of green, it's doing well, and it can float. I use TNC lite fertiliser as recommended by the late and great Byron, as it apparently does not add additional nitrogen like others.
What do you think about the recharging and nitrate free water issue to recharge/rinse? Just grin and bear it, I think.