Curious. I wonder if the precipitate might be magnesium carbonate. That doesn't normally happen, but if magnesium and pH and alk are high, it might. 
I have been gone for so long. sorry to let the thread die off. The above posted test results are consistent with multiple batches, never allowing the batch to sit for more than a few days, always circulated.
In any case. i switched to the red sea blue bucket. i developed a miinor cyano issue almost immediately with the Coral Pro. my params are all in check, and it is a slow battle, though today i am on the winning side. i do believe there is something in the coral pro that adds to the development of cyano. switching to the blue bucket has shown to keep my params almost spot on, allowing me to use biopellets again, however, i have increased my alk dosing via kalk for now.
I switched to Coral Pro 6m ago and immediately got Cyano as well. Have been fighting with it since but just switched to ESV B-Ionic and have done 2 water changes and mysteriously enough, the Cyano is now going away. Go figure.
I do think I had a bad batch though because it mixed up with the following @1.0264:
CA=440
ALK=9.8
MG=1300
It claims to be evaporated real sea water and contains bacteria?
Could that be the problem. I see a very similar case(cyano) developing when one doses too quickly with vodka and or vinegar
I'm beside myself right now.... When I got into this hobby a year and a half ago, I made the mistake of mixing up my instant ocean reef crystals and immediately doing my water change. Finding out soon after that doing that is harmful to the fish by burning their gills, I stopped. I would mix for 24 hours prior to water change after being told that was the correct way. I switched to Red Sea pro a year ago and have been doing it the same way this whole time. I've fought with low Alk and dying Sps, never understanding why. After dealing with the "brown residue" in my newly mixed water, I would periodically turn my power head on/off over the 24 hour period. This actually helped the browning, but my alk has still been low. Long story short, you guys are saying you're having high alk issues with Red Sea pro and I've never seen anything over 8.4. Also, mixing for no more than 4 hours and doing the WC following the mixing period won't harm the fish?? If this is true, sounds like I now know what I need to do aside from dosing. Also, I've only experienced one brief bout with cyano while using Red Sea pro. I would fight cyano once a month with instant ocean.
That may explain why the inside of my reservoir was growing mold on the sides. I tried using this salt, but between the residue on the bottom, the cloudiness for days and the mold I discovered growing on the sides of the mixing reservoir, I went back to ESV. I still have half a 5 gallon bucket of RSCP remaining which will never be used in my tank.
Unfortunately that wasn't my experience. I cleaned out the mixing reservoir or I'd take pictures. The ESV leaves nothing at the bottom when mixed and is ready to use in an emergency, as soon as it's mixed.I've been using Coral pro for almost a year now. I have a 30 gallon brute that I mix my salt in and there is no mold or any residue. Red Sea has been the fastest mixing salt I have ever used and it leaves nothing behind.
Typically the only thing that "burns" their gills is Chlorine. The mixing time and letting it sit for 24+ hours hours is related to chlorine dissipating. If you use RODI water (chlorine will be removed by carbon blocks) and the salt is completely mixed, it will not burn them.
Lol, I can't believe I was under that misconception for so long..... Thanks for clearing that up for me. Yes, I'm using RO. Hopefully things will begin to change for the good.
I've been using Coral pro for almost a year now. I have a 30 gallon brute that I mix my salt in and there is no mold or any residue. Red Sea has been the fastest mixing salt I have ever used and it leaves nothing behind.
After mixing the salt as per the recommendation, do you then just let it sit stagnant, or do you run a small powerhead on a timer every few hours?? So...what are you doing different than everyone else, to keep it clear?? Please share.....I have a bucket in my basement that I planned on using once I add a few more SPS and would have the need for higher Ca, Alk, and Mg.
Right now I use the IORC and after it's thoroughly mixed cold overnight, I then run a small powerhead on a timer ( 1/2 hour on, 3 hours off) and have had good success. I keep it cold....then transfer to a separate container and only heat what I need. I have the same Brute Container and I like having stored premixed saltwater on hand in case of an emergency.