We have hard water and use hemp doublers and inserts (just a few) and I don't have any stink issues. We did when I tried Charlie's Soap and Rockin Green, along with instant ammonia rashes. One wash with Tide and it cleared everything up. I know Tide isn't "eco friendly" but it's the only thing (or All Free/military) that will work with our water.
I've seen many mamas say this about the Tide. I'm just going to start off with Tide HE from the very beginning I guess.
I couldn't use Tide due to DH's eczema, so maybe that is why we had issues with hemp? Not sure - we had well water that was high in sulphur and iron which also could have been the culprit.
I've used Dawn dishwashing soap with great success with hard well water high in metals. I had a top loader before, but I used about a tsp of soap to each load and a downyball of vinegar. From the threads Ive read at DS, I should be able to do the same thing with the front loader, just less, 1/2 tspish, and vinegar directly in the fabric softener dispenser..
I like tide though, so that's my current plan but I do think you can do hemp with hard water and no tide. Ive heard of adding a pot of boiling water every now and then through the detergent dispenser to get hemp super clean. Our washer is on a different floor then our kitchen, so that sounds like alot of work. I also think its really important to prep hemp thoroughly or else you are always fighting stink issues because the natural oils arent off.. and they get on everything else.