I too made "receipe 1" and like you, finally managed to disolving it in almost boiling water, about a week later a significant amount baking soda (NaHCO3) precipitated. I had no problem with the Magnesium (MgSO4) or the Calcium (Ca++) solutions.
I'm going to make up a new batch of baking soda solution today, but I'm going to modify the receipe so that everything is mixed in 2 gallons of RO/DI water instead of one, same proportions greater dilution. The extra water is no great shakes to me as I lose more than I dose on a daily basis.
Hopefully, the new concoction will prevent the baking soda from precipitating.
Right now I'm using two Kangaroo 324 enteric pumps to deliver the "Alk" and "Calc", running 8 cc/hr (1/2 strength solutions) to a 90 gal with 65 gal sump which is maintaining my Alkalinity at 10.2 dKH (stable) and 420 meq/L CA++ (Salifert), although today the Ca++ was up to 440, so I may need to make an adjustment when I test again tomorrow
I want to pick up another pump to dose the Magnesium at the same time. The nice thing about the dosing pumps is that once you have it more or less dialed in you can make very small adjustments.
I'm storing my solutions in Kent 5 Gal. AquaDose containers, as I really don't want to make up fresh batches more than once a week. Modified the "standard" Kangaroo feeding bags to adapt them to the Kent containers as the tubing they provided couldn't be used with the pumps.
Little trick I learned working as a Nurse (RN) repairing leaking micro naso-gastric feeding tubes, i.e. snipped off the feeding bag, cut a short length of 1/4" plastic tubing (same as used on RO filters), then superglued (gel) the tubing inside the 1/4", then superglued the 1/4" inside the 3/8" plastic tubing (like RO only 3/8") that Kent supplied with their tubing set.
It would be easier if I could find a plastic 3/8" MPT to 1/4" compression plastic compression elbow, or even a 3/8" compression to 1/4" compression adapter.
Anyway, `nuff said. I agree that it would be nice to maintain a thread for those using Randy's system.
BTW, where did you find the Dowflake? I had to order it on line and the shipping expense was outrageous in comparison the the cost of the product itself.
Regards
Noel