sus water quality, help please

[shnapper20]

hi after struggling to get corals through the qt stage, I have been conducting icp test on water. The water is mixed in a poly 230lt garbage bin using ro water and aquaforrest reef salt , the icp aqua forest supply for the batch says its good, The triton icp says it has high iron and zinc. The ro water I believe to be ok as it has new filters, a new membrane and a new resin filter. The bin I have scrubbed spotless there was rusty like residue in the bin from previous mixes, which ive been told is normal when mixing salt. The only other culprit which could be giving me these readings is the mixing pump which is a Hailea HX-6540 which is supposed to be good for marine. Is this pump ok for mixing? what pump would others recommend to replace it? The pump runs 24hrs when mixing and is then removed from the bin. any ideas on what else can be causing the contaminates? there are no hose clips or metal in the bin , only the stator of the pump.
thanks john

 

[LeBon]

are you checking the tds, at various points, i.e pre and after membrane and di?

actually a tds of 0 doesnt mean its clean but thats another story.

cant imagine a powerhead leaching if it doesnt have tell tale signs.

any 5 dollar powerhead can do this job.. with obvious caveats

 

[shnapper20]

at one stage I had a corroded hose clamp on the mixing pump and I had left it in the mixing bin for over a month before I picked up on it. That was about 6mths ago and I have scrubbed and cleaned the bin until I could no longer see residue on the paper towel I was using to wipe it down. Could the iron and zinc still be leaching from the bin?
I checked the tds after installing the new filters and got 0.

 

[shnapper20]

The pump I stripped and cleaned it looked fine

 

[LeBon]

at one stage I had a corroded hose clamp on the mixing pump and I had left it in the mixing bin for over a month before I picked up on it. That was about 6mths ago and I have scrubbed and cleaned the bin until I could no longer see residue on the paper towel I was using to wipe it down. Could the iron and zinc still be leaching from the bin?
I checked the tds after installing the new filters and got 0.

i doubt it,but for peace of mind just switch it out for the sake of ten bucks maybe. I just use like 100l garbage bins

 

[shnapper20]

maybe ,I thought I should make up some salt in a new bucket and icp test it , it would rule the leaching possibilty out . I have already icp my ro water im waiting on a result.