Do you think the reduced solubility is something to worry about? I agree about keeping them separate if possible but he said he's only using 3 dosers plus one for pH. Would you increase the concentration of micros to make up for it? I'd think with chelated micros it'd be fine, but I'd like your opinion as well.
Also, you mentioned making a concentrate bottle and then pouring that into a main tank? Wouldn't he just siphon straight from the concentrate bottles w/ the dosers?
The micros will mix in just fine with any other component, even in high concentration, but it is always best to avoid any scenario where solubility is even in question, and reduced solubility could potentially lead to residues clogging filters or lines, which is never good.
As for what I was trying to describe when I mentioned mixing a smaller tank first to help with dissolving, I must not have said that clearly enough, but @Savage Henry understood me and said it in some other words for me to maybe help you guys understand what I was trying to say:
If I may chime in, some salts are difficult to get fully dissolved, especially in large quantities in a large resevoir or stock tank. In practice I've come to mix them in the amount bound for a larger volume of water in 2-3 gals of water (0.0ec). You get a paint stirrer and attach it to a drill and whip em in the small container until dissolved, then pour it into the final volume.
But, as I said, some are more difficult than others. Calnit dissolves super easy whereas k2so4 is a bitch. There's a chart floating around somewhere (maybe science in hydroponics) that outlines maximum solubility of salts.
My experience with dosers has always been in large gardens, so that advice it really directed at concentrate tanks that are too large to shake or stir easily (20gal+), but it sounds like the tanks for concentrate solution being used in this garden are only 5 gallon, which would be easily mixed and shouldnt need any preliminary mixing.
(This post is technically my 1000th comment! I hope no one minds a quick photo bomb on this thread to celebrate, the 1600+ plants in this room are all fed for a total cost of 50 cents worth of nutrients each day, using nothing but the dry salt recipe I have outlined in past posts!)