There is nothing wrong with this salt, it has been proven safe and consistant for many many years; however, I am not saying that there are not better salts formulated to have higher levels of some elements that are more suited to reef tanks vs FOWLR.

I am happy with IO

i can guarantee you that thousands and thousands of successful systems also don't us IO.

it was / is not my intention to bash IO or say there is anything wrong with it. i have only been in SW for about 7 or 8 years and had never used IO. i bought a few pails at the BA's boxing day sale because of the price and all the online praise of the salt. from my testing it was low in all the important params, mixed poorly, had stuff floating on top and left a residue on my heater and mixing pump.

maybe i just expected to much after years of reading how good the stuff was.

A happy IO salt user after I found easy (and still cost effective just to buy Ca and Mg and supplement before adding to tank.

Not always, seems to depend on pail, find a bit of a brown line on my SW mix can after a little evaporation. Never seem to notice a film on the water though.