Nitrate Weirdness

[johnnyjtaylor]

I noticed my toadstool wasn't looking so good and not extending its polyps for a few days(at first I thought it was shedding but it wasnt) then my gsp's stopped looking so good. Out came the test kits and to my horror the nitrates were up to 30ppm or so So I made up 25l of water(a big change in my tank 125l) and just out of curiousity before I did the change I tested it for nitrates it was 20ppm I had just changed to aquamedic reef salt getting myself a big 25kg bucket and so assumed I'd got a dodgy batch (as the water out of my ro unit tested 0ppm).So I went and got a bag of a different brand from lfs. Made up another 25l left it mixing and heating overnight and tested it this morning 20ppm nitrate
So I tested water from my ro again 0ppm, then I mixed some of both brands of salt in clean glasses with ro water both 0ppm, then i took apart my mixing pump and fished some of the sludge out from inside(its just mineral build up the pump has only ever mixed up new salt water) dissolved loads of it in ro water tested it and theres just a tiny trace of nitrate(as I would expect as it just came out of water with 20ppm nitrate).
This leaves the bucket itself looking like the most likely candidate. Has anyone ever heard of a plastic bucket leeching nitrates into water? Its a decent food quality bucket made for fermenting which I assumed would mean it wouldn't release chemicals into the water.
I'm currently heating and pumping some plain ro water in the bucket which I'll leave going for the rest of the day and test later to see what happens.
Any ideas anyone?? Your thoughts would be much appreciated.

 

[n3ont3tra]

This is just a guess, but aren't the test kits for saltwater? RO is freshwater, so it wouldn't work right for RO water, I don't think.

 

[Filmoholic]

how deep is your sandbed? do you run a skimmer?

 

[Musho3210]

i would blame the tank rather than the mixing container.....

 

[littleme1969]

This is just a guess, but aren't the test kits for saltwater? RO is freshwater, so it wouldn't work right for RO water, I don't think.

Very good point!! It could be a test issue as well as other minor problems.

 

[andywg]

I haven't heard of buckets leaking nitrates, but I have heard of tests showing nirates with pure RO+salt water, even up to 100ppm. I tend to blame the tests (I found API tests particularly awful for nitrates).

 

[johnnyjtaylor]

This is just a guess, but aren't the test kits for saltwater? RO is freshwater, so it wouldn't work right for RO water, I don't think.

No the test I use is a nutrafin liquid test it does both FW and SW with a different colour chart for each.

how deep is your sandbed? do you run a skimmer?

Indeed I run a skimmer a mce600 which is rated for a much larger tank than mine(so no problem there). Sand is about 2" depth.Anyway the main issue seems to be in the mixing bucket not the tank.

I haven't heard of buckets leaking nitrates, but I have heard of tests showing nirates with pure RO+salt water, even up to 100ppm. I tend to blame the tests (I found API tests particularly awful for nitrates).

That was my first thought Andy but I mixed a sample up in a glass container and that reads zero nitrate.(possibly the extra few degrees C when heated messes with the test result?). However I made up another batch yesterday afternoon and used an air line to stir it instead of the usual pump(which I said in my original post has some slimey mineral build up inside) and that currently reads 5ppm.
I'm still scratching my head on this one!!