Water test show critically low major and minor causing coral problems?

[Dom]

That may be the culprit... I have used IO a ton and personally have never had any consistency issues, however, there have been complaints and anecdotal accounts of IO being low on elements or having results inconsistent to what is on the label. Most hobbyists use IO Reef Crystals and swear by it. It may be worth considering a switch to the Reef Crystals or a different brand formulated for a reef tank.

I have been using IO throughout my time in the hobby (maybe 15-20 years... who knows). Overall, I am very happy with the quality of the product. However, there were two times when it didn't mix to the stated levels. In both instances, BRS replaced it at no charge.

I am a proponent of faithful, weekly, 20% water changes. In a 75 gallon tank, that is 15 gallons weekly. It has been my experience that adequate levels can be maintained through water changes... at first. But as your corals grow out, demand increases and dosing becomes necessary.

Maybe consider sticking with weekly water changes for 6-8 weeks, then reassess.

 

[crappie]

Well, if it was the low elements, causing issues with the coral. I would think that everything would bounce back now that it is 100% new! Only time will tell I guess

 

[Dom]

Well, if it was the low elements, causing issues with the coral. I would think that everything would bounce back now that it is 100% new! Only time will tell I guess

I know it is hard to be patient when your tank is struggling. But understand that the issue that is causing the problem may have been going on long BEFORE it presented itself visually. With that in mind, the bounce back won't happen overnight either.