I saw several colonies of pink palythoas slowly eject small (BB sized) spherical brown balls. They were slightly bouyant. It looked like each polyp would slowly form and eject a ball out of the "mouth". Any idea what was happening?

In the "mouth" of the polyp, a small lump forms that slowly grows. After about 5 minutes, the lump looks more like a small brown BB that separates from the polyp and slowly floats upward until it is caught by the current and gets shot around the tank. I see one "eject" about every 10 minutes. It looks like each polyp is creating/ejecting a ball. The bigger the polyp, the bigger the ball. It is quite interesting. I have 3 separte clusters of pink palythoas in my tank. I have seen polyps from two separate colonies eject the brown balls.

Is this some mass pooping or reproduction?

Well, it's ood that it's all happening at the same time. That sounds like a reproductive event. However, brown usualy menas poop, or zooxanthellae expulsion. How long have they been in your tank?

Sounds like a spawning event to me. Never seen it happen though.

Just increase lighting? "brown" sounds like Zooxanthellae dumping.

I agree, it sounds like zooxanthellae expulsion to me too. Eggs are usually a whitish color from what I have heard and read about it.

The palythoa coloney has been in the tank about 8 months and has multiplied into three separate groups during that time (polyps floating to new rocks across the tank).

I did replace the actinic bulb a few days ago.

The palythoas looked excellent today. If it was a zooxanthellae expulsion, would that result in a loss of color?

In another forum, several folks insisted the balls were poop. There are no signs of the balls in the tank now. I would have to agree that poop seems the most likely explanation. However, it is facinating that many, if not most (I saw 30-40), of the polyps in 3 separate groups/colonies of palythoa would participate in a syncronized mass pooping event over the course of 1-2 hours! Amazing!

[Maybe I unknowingly added a palythoa laxative to my tank]

They all seem happy now.

Dan, It wouldn't necessarily result in loss of color.

Now get to a store and get palythoa immodium for your tank ;)

Dave