Sounds like you need to mix it up more.I do the full line up at 5 gallon each watering day and dont get that.
In my opinion this is the particulate that comes in the Big Bloom from the organic ingredients such as EWC and guanos. Shake the bottle well each use and stir a LOT when adding to water. This is just residue and not the evidence of a chemical reaction in which some elements have precipitated to the bottom as sometimes occurs in hydro res. If feeding in soil or any system clogging is not an issue dont worry about it. If using a drip or even an ebb system where it could be a problem just run it through a screen or filter all the needed elements will make it through and you can still throw that (sand) into an outdoor garden
In my opinion this is the particulate that comes in the Big Bloom from the organic ingredients such as EWC and guanos. Shake the bottle well each use and stir a LOT when adding to water. This is just residue and not the evidence of a chemical reaction in which some elements have precipitated to the bottom as sometimes occurs in hydro res.