Yellow will turn green with high nutrients or low light. You will likely need undetectable nutrients levels to have true yellow. How are your nitrates? I don't think iron will be an issue unless you are dosing it.

I have no nitrates. I can't get cheato to grow my magroves grow very slow and I have a algea scrubber that been running for 2 weeks now. I have also been using prodibio for 12 weeks. I have been testing water biweekly. Two months ago I had a po4 problem but have since rectified it. I run a mr1 reactor with phosban. I have great colors in Sps like garf bonsi. No other corals are off colored except a purple digi which brownish with purple tips.
I also have a white and fluorescent yellow frag of my brothers on my frag rack which has maintained color.

I have three 250 watt Mh @ 20k. Two t5 @ 10k. Two antinic t5

Nitrates, phosphates and lighting effect all SPS. If color is good everywhere else I would rules those out. While I agree high iron is unlikely unless you dose, low iron is very likely however it's not your tank that has the issue. Your "yellow" stag could have come from a low iron tank and is actually a green stag which are more common.

Since you have a yellow coral that's maintained it's color I'd agree it's likely the coral and not your tank.

Lots of yellow SPS on the coast, maybe the prairie reefers are stingy with their nice corals :surprise: Pink Lemonaid has a nice yellow if you can get it.

Agreed. This is my only true yellow coral.

Ditto

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Thanks for everyones input.

I have found some mini colonies that have great looking yellows.

I guess lighting would be the factor for my stag as the tank it came from ran 10k lights so I can see my 20k changes the colors

True yellow is hard to find I only have 2....a tyree pink lemonade and another pink lemonade look a like.

A lot of times zeo, ULNS or super high lighting may turn a normally green coral yellow. Also green coral often look yellow after they have under gone shipping stress.