i know u said water is stable but post ur parameters is nitrate or phosphate up at all ? Alk swings can cause this, nitrates can cause some colonies to be stressed and others look fine

I've never tested nitrates in 10+ years. Gonna start testing nitrates when Hanna releases a handheld colorimeter if it's affordable.

Phosphates are .06 on a Hanna. This is low for my tank as po4 is usually .08-.10 in my tank over the last 4 years.

You should probably test NO3. If it's steadily increased over the years, it could reach critical levels. PO4 is even a bit high IMO. I aim for 0.00, hoping to be under 0.03ppm. NO3, I aim for less than 1ppm

Hrm weird, is anything stinging them? I had two big colonies come close and ended up losing both to stn,

NO3 could be high as I haven't ever tested. I've always vinegar dosed to control nitrates but never tested. My aim has always been off on PO4 but corals have done well especially Sept-March with PO4 around .10. Tried gfo and fozdown but never been able to maintain PO4 in the "ideal" range.

This scare is gonna make me a better reefer as I've had a long lucky streak just doing large regular water changes. Just hope I don't loose anymore large colonies.

It's possible but these corals have been intertwined and criss-crossing for almost 2 yrs with no issues.

You may continue to lose them until you figure out why. Test anything you can. If you don't have a kit for NO3, drop by here with some water tomorrow night.

The steady rise in nitrates is what I'm battling now after really not testing it for like 2 years finally tested it and was presently surprised with decently high levels and started to notice high end acans and deep water acro just not looking as good ... maybe same thing for you?

Ok thanks. Not tomorrow but soon. Very soon

Nothing you've said led me to believe you had AEFW. It's definitely something to check for though.

How's flow? Have you increased it over the years as the corals have grown?

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